Evaluating Shrink Swell Characterstics of Expansive Soils in Some Areas of Amhara Region

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Geotechnical Engineering Thesis

2020-03-11 EVALUATING SHRINK SWELL CHARACTERSTICS OF EXPANSIVE SOILS IN SOME AREAS OF AMHARA REGION

Mekonen, Belaynesh http://hdl.handle.net/123456789/10267 Downloaded from DSpace Repository, DSpace Institution's institutional repository

BAHIR DAR UNIVERSITY BAHIR DAR INSTITUTE OF TECHNOLOGY SCHOOL OF RESEARCH AND GRADUATE STUDIES FACULTY OF CIVIL AND WATER RESOURCES ENGINEERING

EVALUATING SHRINK SWELL CHARACTERSTICS OF EXPANSIVE SOILS IN SOME AREAS OF AMHARA REGION

Belaynesh Mekonen

September 4,2019

Bahir Dar, Ethiopia

EVALUATING SHRINK SWELL CHARACTERSTICS OF EXPANSIVE SOILS IN SOME AREAS OF AMHARA REGION

Belaynesh Mekonen

A thesis submitted to the school of Research and Graduate Studies of Bahir Dar Institute of Technology, in partial fulfillment of the requirements for the degree of Civil Engineering master of science in (Geotechnical Engineering) in water resources and civil engineering.

Advisor Name: AddiszemenTeklay (PhD)

Bahir Dar, Ethiopia September 4, 2019

BELAYNESH MEKONEN WELAHAWARIAT

ACKNOWLEDGEMENTS

First and most of all, I would like to thanks almighty God for blessing and being with me in every step pass through.

I would like to express my sincere gratitude to my advisor, Dr.Addiszemen Teklay, Bahirdar University, Technology Faculty, for his valuable advice, support, encouragement throughout this work. His excellent guidance, thoughtful criticism, innovative ideas.

I would like also to thank my sponsorship Bule hora university for giving me the opportunity to pursue post graduated study.

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To my father and mother

ACKNOWLEDGEMENTS

First and most of all, I would like to thanks almighty God for blessing and being with me in every step pass through.

I would like also to thank my sponsorship Bule hora university for giving me the opportunity to pursue post graduated study.

ABSTRACT

The research is mainly determining the degree of expansiveness and shrinkage swell characteristics of soils in some areas of Amhara region.

Accordingly, several data were taken from design office and from theses that were done before on different local places. Relations obtained from statistical analysis between the index properties, and swelling pressure with index properties of expansive soil.

Equations were developed, by taking one or more of the soil property parameters (Liquid limit, plastic limit, shrinkage limit, moisture content, dry density and plastic index) in different combinations.

Based on the experimental results obtained from different theses, correlations and empirical equations have been developed. The multiple regression Analysis indicates that there is a relationship between index properties and swelling characteristics of expansive soils in some areas of the region. The developed equations could be used for estimation of swelling characteristic of the soils in the study areas.

The suggested equations used for the estimation of the swelling pressure of the areas are the equations with higher coefficient of estimation. Five equations have been selected to predict the swelling pressure of soils of the region. From such equations (Eqn. 3) more preferable than the others due to R2=0.999, MSE (error) =0.0037

In addition evaluation of one point liquid limit test has been checked for expansive soils of Amhara region. Accordingly, several data were taken from different theses that were done before. The relations obtained from statistical analysis have R2 of 0.83.

Key words: Swelling pressure, degree of expansiveness, Predictive model, Correlations, some areas of Amhara region, soils

TABLE OF CONTENTS

DECLARATION ...... ERROR! BOOKMARK NOT DEFINED.

ACKNOWLEDGEMENTS ...... III

ABSTRACT ...... VI

TABLE OF CONTENTS ...... VII

LIST OF ABBREVATIONS ...... X

LIST OF SYMBOLS ...... XI

LIST OF FIGURES ...... XII

LIST OF TABLES ...... XIII

1. INTRODUCTION ...... 1

1.1 Background ...... 1

1.2 Problem Statement ...... 2

1.3 Objective of the study...... 3 1.4.1General Objective ...... 3 1.4.2 Specific objectives ...... 3

1.4 Significance of the study ...... 3

2 LITERATURE REVIEW ...... 4

2.1 General ...... 4

2.2 Theoretical back ground of expansive soils ...... 4 2.2.1 Definition of Expansive soils ...... 4 2.2.2 Formation of Expansive soils ...... 4

2.3 General Characteristics of Shrink Swell Soil...... 5

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2.4 Factors Responsible for Shrink-Swell Phenomena in Expansive Soil ...... 6

2.5 Clay Mineralogy and Mechanism of Swelling ...... 8 2.5.1 Clay Mineralogy and its Effect ...... 8 2.5.2 Clay Particles-Water Relations ...... 10

2.6 Identification and Classification of Expansive soils ...... 11 2.6.1Tests conducted for Identification ...... 11 2.6.2 Factors responsible for Shrink Swell Behavior of soils ...... 12 2.6.3 Determination of swelling properties ...... 12

3 STUDY AREA ...... 14

3.1 Introduction ...... 14

3.2 Climatic Characteristics of the Amhara region ...... 15 3.2.1 Annual and Seasonal Rainfall Variation ...... 15

3.3 Geography of Amhara region ...... 15

3.4 Factors responsible for Formation Expansive Soil in the study area ...... 16 3.4.1Topography ...... 16 3.4.2 Drainage Characteristics of the Soils ...... 16 3.4.3 Rain fall ...... 17 3.4.4 Temperature...... 17

3.5 Expansive soil testing practice...... 17

3.6 Evaluation of Expansive soil Engineering Properties ...... 18 3.6.1Visual identification ...... 18 3.6.3 Index Properties of Expansive Soils ...... 18

3.7 Damages Caused by Expansive soils in the region ...... 21

4 METHODOLOGY ...... 24

4.1 GENERAL ...... 24 4.1.1 Methodology of study ...... 24

4.2 Data Collection and Analysis...... 25 4.2.1 Test Results ...... 25 4.2.2 Characterization of Expansive soils in some areas of Amhara region by some parameters ...... 26 4.2.3 Classification of Expansive Soils ...... 33

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4.3 Correlation of index properties and swelling pressure with index properties of soils in the study area ...... 40 4.3.1 Introduction ...... 40 4.3.2 Data used for Analysis ...... 40

4.4 Relationship between Liquid limit and Moisture Content of Expansive soil of Amhara Region ...... 41

4.5 Relationship between moisture content with liquid limit, plastic index and dry density ...... 46

4.6 Relationship between Swelling Pressure and Index Property...... 46 4.8.2 Statistically Analysis Linear and non Linear multiple Regression Analysis 49

5 RESULTS AND DISCUSSION ...... 51

5.1 Swelling Pressure vs. Plasticity Index...... 51

5.2 Swelling Pressure vs. Natural Moisture Content ...... 51

5.3 Swelling Pressure vs. Dry Density...... 51

5.4 Development of swelling pressure Predictive model from index properties of expansive soils ...... 52 5.4.1 Data used for model development ...... 52

5.5 Models Developed by Various Researchers ...... 52

5.6 Evaluation of previous models for the soils in the study area ...... 53

5.7 Development of Empirical Equations ...... 54

5.8 Graphical Representation of the Measured and Calculated Values ...... 57

5.9 Prediction of Swelling Pressure for the study area ...... 60

6 CONCLUSIONS AND RECOMMENDATIONS ...... 69

6.1 Conclusions ...... 69

6.2 Recommendations ...... 70

REFERENCES ...... 71

APPENDIX-A ...... 73

LIST OF ABBREVATIONS

Ac Activity of clay AASHTO American Association of Highway and Transportation Officials ANRS Amhara national regional state ASTM American Society for Testing Materials standard BDU Bahirdar University C Clay D Depth Fs Free swell LL Liquid limit M Metter Wn Natural moisture content PI Plastic Index PL Plastic limit SP Swelling pressure TP Test pit USCS Unified Soil Classification System γd Dry unit weight N Number of blows Vs Verse

LIST OF SYMBOLS

tan β - slope of the flow line on a semi log plot (mean value for a given soil)

MH – Inorganic Elastic silt

ML – Inorganic Silt

SM –Silt sand

LIST OF FIGURES Figure 2:1Polygonal pattern of surface cracks in the dry season. (J. David Rogers, Robert Olshansky, and Robert B. Rogers , Journals) ...... 7 Figure 2:2 Narrower, less straight cracks may extend much deeper. (J. David Rogers, Robert Olshansky, and Robert B. Rogers Journals) ...... 7 Figure2:3 (a) Silica tetrahedrons, (b) silica sheets, (c) single aluminum octahedrons, and . 9 Figure2:4: Structure of (a) kaolinite, (b) illite, and (c) montmorillonite ( Fasil Abagena,2003,) ...... 10 Figure3:1Mapofthestudyarea/Amhararegion/ (http://www.etharc.org/Amhara/About%20Us/Geography.htm) ...... 14 Figure 4:1Flow Chart of the Research Methodology ...... 25 Figure 4:2 Mineral activities (AgusTugas S., M.Cakrawala, and Candra A., (2012)) ...... 27 Figure4:3Charts for use in AASHTO soil classification system ...... 35 Figure 4:4Scatter plot of N/25 Vs LL/Wn...... 44 Figure 4:5 Correlation swelling pressure with plastic index ...... 47 Figure 4:6 Correlation swelling pressure with water content...... 47 Figure 4:7 Correlation swelling pressure with dry density in Bahirdar ...... 48 Figure 4:8 Correlation swelling pressure with plastic index ...... 48 Figure 4:9 Correlation swelling pressure with moisture content ...... 49 Figure 4:10 Correlation swelling pressure with dry density ...... 49 Figure 5:1 Bahirdar soils Equation 1 vs. measured value ...... 57 Figure 5:2 Bahirdar soils Equation 2 vs. measured value ...... 58 Figure 5:3Validation of equation 1 for Bahir dar soils ...... 58 Figure 5:4 Debre tabor soils Equation 1 vs. measured value ...... 59 Figure 5:5 Debre tabor soils Equation 2 Vs measured value ...... 59 Figure5:6 Validation of equation 1 for Debretabor soils ...... 60 Figure 5:7 Normality of and predicted and calculated swelling pressures ...... 62 Figure 5:8 Normality plot and predicted and calculated swelling pressures ...... 65 Figure 5:9 Normality plot predicted and calculated swelling pressures ...... 67 Figure 5:10 validation graphs ...... 68

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LIST OF TABLES

Table 2:1swelling potential vs. plasticity index ( AgusTugas S., M.Cakrawala, and Candra A., (2012)) ...... 12 Table 3:1 Annual seasonal rainfall trend during 1975-2003(Woldeamlak Bewket1)...... 15 Table 3:2moisture content values ...... 19 Table 3:3Grain size distributions of some areas of Amhara region ...... 20 Table 3:4Atterberg limit test results of Amhara region ...... 21 Table 4:1 Summaries of test results ...... 26 Table 4:2Classification of soils based on activity ...... 28 Table 4:3 Different states and consistency of soils with Atterberg limits...... 29 Table 4:4 Soil consistencies based on the unconfined compressive strength ...... 29 Table 4:5 free swell range ...... 30 Table 4:6 Soils expansiveness ...... 31 Table 4:7 swelling properties of soils...... 32 Table 4:8 swelling properties ofAmhara region soils ...... 32 Table 4:9Typical Atterberg limits for soils...... 32 Table 4:10 USCS of the soils of Amhara Region ...... 33 Table 4:11engineering properties of the soils ...... 33 Table 4:12 AASHTO soil classification system...... 35 Table 4:13 comparisons of the liquid limit values ...... 36 Table 4:14 comparisons of the plastic limit values ...... 37 Table 4:15 Comparison of the plastic index values ...... 37 Table4:16 Comparison of specific gravity values ...... 38 Table 4:17 comparison of the swelling pressure values ...... 38 Table 4:18 comparison of the Natural moisture content values ...... 39 Table4:19 comparison of clay content ...... 39 Table4:20 comparison of silt content ...... 39 Table 4:21Test results of particle size distribution ...... 41 Table 4:22, 271 points of LL/Wn and N/25 data ...... 42 Table 4:23output of NCSS software ...... 45 Table 5:1Comparison of Previously Developed Equations with the Measured Value ...... 53 Table 5:2 Comparison of Measured value with Calculated Value (Dagmawi Niguse 2007)55 Table 5:3 Debre tabor swelling pressure (Belay Belete 2014) ...... 56 Table 5:4 checking of validation of the equations for control points Debre tabor soils .... 57 Table 5:5Analysis of variance of Amhara region ...... 60 Table 5:6Predicted Values with Prediction Limits of swelling Pressure ...... 61 Table 5:7Analyses Of Variance ...... 63 Table 5:8Predicted Values with Prediction Limits of swelling Pressure eqn 2 ...... 64 Table 5:9 Measured, Predicted Values with Prediction Limits of swelling Pressure ...... 65 Table 5:10 Comparison of Measured value with Calculated Value for Control Samples 67

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1. INTRODUCTION

1.1 Background

The historic Amhara Region contains much of the highland plateaus above 1500 meters mean sea level (m.s.l) with rugged formations, gorges and valleys, and millions of settlements for Amhara villages surrounded by subsistence farms and grazing fields. Fissures in the soil can also develop. These fissures help water to penetrate to deeper layers. This produces a cycle of shrinkage and swelling that causes the soil to undergo great amount of volume changes. This movement in the soil results in structural damages especially in lightweight structures such as one or two story buildings, warehouses, retaining walls, sidewalks, driveways, basement floors, pipelines and foundations (Ayenew, Z., 2004).

Expansive soils owe their expansive character mainly to the constituent clay mineral. The most important clay mineral, mainly responsible for expansiveness nature is montmorillonite (Ayenew, Z., 2004). Montmorillonite has an octahedral sheet sandwiched between two silica sheets. When this mineral is exposed to moisture, water is absorbed between interlayering lattice structures and exert an upward pressure. This upward pressure, known as swelling pressure, causes most of the damages associated with expansive soils.

Most of the structural damage on expansive soil results from the differential rather than the total movement of the foundation soil as a result of swell. Differential movements distribute equilibrium of a system by redistributing the structural loads causing concentration of loads on portions of the foundation and large changes in moments and shear forces in the structure not previously accounted for in the standard design practice.

Types of structures most often damaged from swelling soil include foundations and walls of residential and light weight (one or two story) buildings, highways, canal and reservoir linings, and retaining walls. Lightly loaded one or two story buildings, warehouses, residences, and pavements are especially vulnerable to damage because

these structures are less able to suppress the differential heave of the swelling foundation soil than heavy, multi-story structures(Eyasu Minichle,2015).

Therefore, in order to design light weight structures on expansive soils, determination of index properties, swelling pressure and shear strength parameters of the soil is necessary. Many investigations have been conducted on the properties of Expansive soils found in different areas of Amhara region. In this research, the intention is evaluating the shrink swell properties of expansive soils and characterization of the engineering properties of soils of Amhara region based on detail literature review.

1.2 Problem Statement

Presence of montmorillonite is considered to give a higher degree of volume change than the presence of either illite or kaolinite. If volume change is prevented by controlling the boundary conditions, swelling pressures will develop. These are the effects of the release of internal stress, associated with hydration and osmotic phenomenon. They may be represented by the loading which has to be applied to a soil to prevent swelling when in contact with water. The characteristic of an expansive soil to undergo change in volume with change in moisture content causes great damage to structures. Beneath the center of the building, where the soil is protected from rain and sun, the moisture content changes are minimum. In arid regions where the soils are normally dry, the problem is somewhat different. Added moisture from leaking pipes and irrigation, or the reduction of moisture through evaporation caused by the presence of a building or a pavement can bring about appreciable swelling. When the source of moisture is eliminated, the movement will reverse, causing the same damage to structures as the seasonal volume changes. In humid regions where the soils are ordinarily moist, severe desiccation may cause susceptible soils to shrink and bring about severe settlement of structures. Associated with the volume changes the swelling pressures are developed. These are important because differential wetting means that the soil will differentially exert an upward pressure on the structure. Unless the structure is loaded heavily enough to resist the

swelling pressure developed, it will distort. Therefore the characteristic of an expansive soil causes great damage to structures.

1.3 Objective of the study

1.4.1General Objective The general objective of this research is to determine the swell characteristics of expansive soils in some parts of Amhara region using theses done before and design office data done related to expansive soils.

1.4.2 Specific objectives  To provide a summary on a geotechnical Characteristic of the expansive soils by their Engineering properties for design and construction.  To check validation of one point liquid limit test method for expansive soils of the region  To develop correlation between index properties of soils that is suitable for the type of soil in the study area.  To compare the newly developed model with similar models(developed with correlations and index properties and swelling characteristics) done in Ethiopia and abroad.

1.4 Significance of the study

Multiple construction projects of different size are undergoing in the region. The output of the research will provide preliminary background information on the value of swelling pressure, for a localized expansive material, from soil index properties with a benefit of time saving and without incurring any additional cost for carrying out laboratory swelling pressure test. Which gives information regards the swelling properties of the soil.

These studies provide direction for other related researches in the area. The newly developed models equations could be used for estimation of swelling characteristic of the soils the study area for designers/consultants and the construction and design office of the region.

2 LITERATURE REVIEW

2.1 General

Accomplishing the general and specific goals of this research requires a good understanding of the Engineering properties, testing practice and problems in design and construction of expansive soils in Amhara region .

This chapter summarizes the above aspects of expansive clays and reviews several previous studies conducted by different researchers in the region starting from the theoretical back ground information on expansive soil characteristics.

2.2 Theoretical back ground of expansive soils

2.2.1 Definition of Expansive soils

Expansive soils are residual soils formed as the result of weathering of the parent rock. These soils become wet during rainy seasons and dry or partially saturated during the dry seasons. In regions which have well-defined, alternately wet and dry seasons, these soils swell and shrink in regular cycles. Since moisture change in the soils bring about severe movements of the mass, any structure built on such soils experiences recurring cracking and progressive damage (Adem Ebrahim 2014).

Expansive soils swell when water is added, and shrink when they dry out. This continuous change in soil volume causes structures to move unevenly and crack. This is more than twice the damage from floods, hurricanes and earthquakes combined.( Tibebu Solomon ,2015).

2.2.2 Formation of Expansive soils

As igneous rock (primarily volcanic ash) breaks down through chemical weathering, it creates the clays.

Weathering breaks the parent rock apart and allows the atoms to recrystallize. These form Silicon Tetrahedron Sheets and Aluminum Octahedral Sheets.

Kaolinites are formed in well drained soils, with an abundance of Oxygen, Silicon and Aluminum. Since the constituents are "pure", these form very regular shapes which bind together in regular structures. These are held together in large stacks by strong Hydrogen Bonds.

Montmorillonites are formed in poorly draining soils and a wide variety of atomic species are available for recrystallization. When the aluminum octahedral is trying to form, sometimes "isomorphic substitution" occurs in which a magnesium atom substitutes for an aluminum atom. This creates irregular shapes and unbalanced charges with weak "van der Waals" forces between them.

To be electrically balanced, montmorillonites develop micelles with water and cations depending on the environment in which the clays form, they may be dispersed.

2.3 General Characteristics of Shrink Swell Soil

Swelling soils, which are clayey soils, are also called expansive soils. When these soils are partially saturated, they increase in volume with the addition of water. They shrink greatly on drying and develop cracks on the surface. These soils possess a high plasticity index. The color varies from dark grey to black. It is easy to recognize these soils in the field during either dry or wet seasons. Shrinkage cracks are visible on the ground surface during dry seasons. The maximum width of these cracks may be up to 20 mm or more and they travel deep into the ground. A lump of dry black cotton soil requires a hammer to break. During rainy seasons, these soils become very sticky and very difficult to traverse.

Expansive soil is a term generally applied to any soil or rock material that has a potential for shrinking or swelling under changing moisture conditions (Ayenew, Z., 2004). Subsequent swelling and shrinkage of this soil due to change in moisture cause damages to different structures, particularly light weight buildings and pavements.

Expansive soils contain the clay mineral montmorillonite with clay stones, shale’s, sedimentary and residual soils are capable of absorbing great amount of water and expand. They are sometimes called black cotton soils, shrink-swell soils, swelling soils,

clay, or soils. They are widely distributed especially in the highlands. Known as vertisols, they are present in the central, north-eastern highlands and western lowlands. (Ayenew, Z., 2004).

2.4 Factors Responsible for Shrink-Swell Phenomena in Expansive Soil

Shrink and Swell in expansive soil can be induced by different factors. Generally, these factors are categorized into three groups namely the soil characteristics, the environmental factors and the state of stress.

Expansive soils owe their characteristics to the presence of swelling clay minerals. As they get wet, the clay minerals absorb water molecules and expand; conversely, as they dry they shrink, leaving large voids in the soil. Swelling clays can control the behavior of virtually any type of soil if the percentage of clay is more than about 5 percent by weight. Soils with smectite clay minerals, such as montmorillonite, exhibit the most profound swelling properties.

In the field, expansive clay soils can be easily recognized in the dry season by the deep cracks, in roughly polygonal patterns, in the ground surface (Fig.2.1). The zone of seasonal moisture content fluctuation can extend from three to forty feet deep (Fig.2. 2). This creates cyclic shrink/swell behavior in the upper portion of the soil column, and cracks can extend too much greater depths than imagined by most engineers.

The most obvious way in which expansive soils can damage foundations is by uplift as they swell with moisture increases. Swelling soils lift up and crack lightly-loaded, continuous strip footings, and frequently cause distress in floor slabs. Because of the different building loads on different portions of a structure's foundation, the resultant uplift will vary in different areas. The exterior corners of a uniformly-loaded rectangular slab foundation will only exert about one-fourth of the normal pressure on a swelling soil of that exerted at the central portion of the slab. As a result, the corners tend to be lifted up relative to the central portion.

This phenomenon can be exacerbated by moisture differentials within soils at the edge of the slab. Such differential movement of the foundation can also cause distress to the framing of a structure.

Figure 2:1Polygonal pattern of surface cracks in the dry season. (J. David Rogers, Robert Olshansky, and Robert B. Rogers , Journals)

Figure 2:2 Narrower, less straight cracks may extend much deeper. (J. David Rogers, Robert Olshansky, and Robert B. Rogers Journals)

2.5 Clay Mineralogy and Mechanism of Swelling

2.5.1 Clay Mineralogy and its Effect Even an expansive soil may never swell, if its moisture content stays constant at all times, but it is obvious that soils undergo moisture content change for a variety of reasons. When an increase in moisture of expansive soils occurs, it causes the soil to expand (swell) and heave. The phenomena may results in expansive soils for the following reasons Rain fall and rise in the ground water table. Reducing load condition, such as surcharge loads increases the swell .Transmission of moisture with time; moisture transmission through soil is slow and requires week sand even years to saturate depending upon the permeability and thickness of stratum.

Dry density, dense clays will swell more when they are wetted than the same clay at lower density with the same moisture content.

Mineral type and amount, soils containing a considerable amount of montmorillonite minerals will exhibit high swelling and shrink age characteristics.

The term clay is applied to the fraction of grains whose equivalent diameter is less than 0.002mm. The individual grains are fragments of a single mineral i.e. a solid compound with a definite chemical composition and unique crystalline structure. The minerals of clays are formed by the weathering of rocks. Most clay minerals of interest to geotechnical engineers are composed of oxygen and silicon- two of the most abundant elements on earth. Silicates are a group of minerals with a structural unit called the silica tetrahedron.

Clays can be divided into three general groups on the basis of their crystalline arrangement. They are: Kaolinite group, Montmorillonite group (also called the smectite group),Illite group.

The kaolinite groups of minerals are the most stable of the groups of minerals. The kaolinite mineral is formed by the stacking of the crystalline layers of about 7 A thick one above the other with the base of the silica sheet bonding to hydroxyls of the gibbsite sheet by hydrogen bonds. Since hydrogen bonds are comparatively strong, the kaolinite

crystals consists of many sheet stacking’s that are difficult to dislodge. The mineral is, therefore, stable and water cannot enter between the sheets to expand the unit cells .soils having a free swell less than 50% are considered as medium in degree of expansion (Teferra A. and M.Leikun., 1999,)

Figure2:3 (a) Silica tetrahedrons, (b) silica sheets, (c) single aluminum octahedrons, and

(d) Aluminum sheets (Fasil Abagena,2003,)

Figure2:4: Structure of (a) kaolinite, (b) illite, and (c) montmorillonite ( Fasil Abagena,2003,)

2.5.2 Clay Particles-Water Relations The behavior of a soil mass depends upon the behavior of the discrete particles composing the mass and the pattern of particle arrangement. In all these cases water plays an important part. The behavior of the soil mass is profoundly influenced by the inter- particle-water relationships, the ability of the soil particles to adsorb exchangeable cations and the amount of water present.

The clay particles carry a net negative charge on their surface. This is the result of both isomorphs substitution and of a break in the continuity of the structure at its edges. The intensity of the charge depends to a considerable extent on the mineralogical character of the particle. The physical and chemical manifestations of the surface charge constitute the surface activity of the mineral. Minerals are said to have high or low surface activity, depending on the intensity of the surface charge .As pointed out earlier, the surface activity depends not only on the specific surface but also on the chemical and mineralogical composition of the solid particle. The surface activity of sand, therefore, will not acquire all the properties of true clay, even if it is ground to affine powder. The presence of water does not alter its properties changing its unit weight. However the behavior of coarser fractions considerable excepting a saturated soil mass consisting of fine sand might change under dynamic loadings.

2.6 Identification and Classification of Expansive soils

2.6.1Tests conducted for Identification The process of estimation of Expansion Potential of a soil begins with search for presence of expanding clay minerals in the soil indirectly from the soil properties and parameters namely percentage passing 75µ sieve, Liquid Limit, Plasticity Index and Free Swell Index. The Liquid Limit, Plasticity Index, Shrinkage Limit and Free Swell Index of expanding clay minerals significantly differ from those of non-expanding clay minerals.

For identification of expansive soils, some laboratory tests are available. Clay minerals can be known by microscopic examination, X-ray diffraction and differential thermal analysis. From clay minerals by the presence of montomorillonite, the expansiveness of the soil can be judged. But the test is very technical.

(Holtez Gibbs) reported that soil having free swell values as low as 100% may exhibit considerable volume change, when wetted under light loading, and should be viewed with caution. Where soils is having free swell values below 50% seldom exhibit appreciable volume changes, even under very light loadings. But these limits are considerably influenced by the local climatic conditions.

The free swell test should be combined with the properties of the soil. A liquid limit and plasticity index, together pointers to swelling characteristic of the soil for large clay content. Also the shrinkage limit can be used to estimating the swell potential of a soil. A low shrinkage limit would show that a soil could have volume change at low moisture content. The swelling potential of a soil as related in general way to plasticity index, various degrees of swelling capacities and the corresponding range of plasticity index are indicated below through table.

Table 2:1swelling potential vs. plasticity index ( AgusTugas S., M.Cakrawala, and Candra A., (2012))

Swelling potential Plasticity index Low 0-15 Medium 10-35 High 35-55 Very high 55 and above

Soils with high swelling potential will actually exhibit swelling characteristics depends on several factors. That of greatest importance is difference between field soil moisture content at the time the construction is under taken and the equilibrium moisture content that will finally be achieved under the conditions associated with the complicated structure. If the equilibrium moisture content is considerable and higher than field moisture content, then the soil is of high swelling capacity, vigorous swelling may occur by upward heaving of soil.

2.6.2 Factors responsible for Shrink Swell Behavior of soils

There are several factors responsible for shrink swell behavior of soils.

Factors depend on the natural properties of soil; Percent of clay, kind of its mineral and positive mutual ions and structural composition, dry density and natural water content.

Factors depend on surrounding environment in site and the building: Thickness of swelling soil layer and the active depth, sources of water, direction and movement of water, mixing or overlap of swelling soil with sandy soil

2.6.3 Determination of swelling properties

2.7.3.1Activity Activity of the soil assesses capacity of soil to hold water. This is applicable for clayey soil. The swelling and shrinkage volume change depends on the activity of clay soil. Active soils have high swelling capacity.

The Activity number is given by the following (equation 2.1).

푃퐼 A= ………………………………………………………………… (2.1) 퐶

Where A= activity, pI = plasticity Index= L.L-P.L, C = % of clay which is less than 2 micron by weight

2.7.3.2 Swelling Pressure Swelling pressure is the pressure corresponding to the absence of the change in volume and is generated when submerged soil sample relates swelling in water. Swelling pressure is measured experimentally in several different ways. The most reliable means of measuring swelling pressure is laboratory determination using one-dimensional consolidometer.

3 STUDY AREA

3.1 Introduction

Amhara Region is located in northwestern Ethiopia between 9°20' and 14°20' North latitude and 36° 20' and 40° 20' East longitude. It has estimated land area of about 170,000 Square kilometers. The region borders are Tigray in the North, Afar in the East, Oromiya in the South, Benishangul-Gumiz in the Southwest and the country of Sudan to the west (http://www.etharc.org/Amhara/About%20Us/Geography.htm).

In the map of Amhara region areas indicated by the circles below in Figure 1.1 are studies conducted by different researchers in several parts of the region focusing expansive soil properties and characterization are reviewed.

Figure3:1Mapofthestudyarea/Amhararegion/ (http://www.etharc.org/Amhara/About%20Us/Geography.htm)

3.2 Climatic Characteristics of the Amhara region

3.2.1 Annual and Seasonal Rainfall Variation The annual total rainfall in the highlands of the Amhara national regional state (ANRS) varies from slightly over 770 mm in Lalibela to more than 1660 mm in Chagni. The annual average areal rainfall in the Amhara region is 1194 mm, with a standard deviation of 124 mm and coefficient of variability of 10.4%.The rainfall in the region is characterized by alternation of wet and dry seasons in a periodic pattern. From the 29 years of observation, 17 years (59%) recorded below the long-term average annual rainfall amount while 12 years recorded above average. The table below indicates Annual and seasonal rainfall trend for 28 years.

Table 3:1 Annual seasonal rainfall trend during 1975-2003(Woldeamlak Bewket1).

Annual rain fall Kiremt Belg Station Trend Rho Trend Rho Trend Rho BahirDar 45 0.17 42 0.16 8.00 0.09 Chagni -24 -0.17 -12 -0.12 -4.00 -0.12 Combolcha 51 0.26 60 0.27 -15.00 -0.16 Dangla -22 -0.03 12 0.36 -19.00 0.56* DebreBirhan 62 0.20 73 0.23 -23.00 -0.16 Dessie 128 0.62*** 107 0.48*** 2.00 -0.04 DebreMarkos 55 0.26 33 0.26 6.00 0.04 DebreTabor -103 -0.28 -101 -0.40* 25.00 0.23 Gondar -36 -0.02 -29 -0.04 19.00 -0.28 Gorgora 29 0.12 11 0.13 10.00 -0.01 Kemissie 34 0.21 30 0.11 5.00 0.04 Lalibela 101 0.47** 104 0.45** -19.00 0.09

3.3 Geography of Amhara region

The regional state is made up of 11 administrative zones with their latitude and longitude, namely Wag Himra,North Wollo(Woldiya11°50'N and39°36'E),North Gondar(Gondar13° 36' N and37° 28'E) South Gondar(Debre tabor 11° 86' N and38° 01'E), South Wollo,

North Shewa(DebreBerhan 9° 41' N and39° 32'E), Oromia(Kemise 10° 43' N and39° 52'E), East Gojjam(Debremarkos10° 20' N and37° 43'E), West Gojjam(Merawi 11° 24' N and37° 09'E), Awi and Bahir Dar(11° 35' N and37° 23'E) . These zones are divided into a total of 113 woredas and 3,216 kebeles.

3.4 Factors responsible for Formation Expansive Soil in the study area

Expansive soils are formed due to variation of surface moisture, permeability of the soil, and climatic conditions. Seasonal changes in rainfall were typically the principal causes of the change of soil moisture. This led to downward movement during summer and upward movement during winter. The consequent rising and falling of ground surface occurred in the dry and wet seasons resulting in seasonal subsidence and seasonal recovery respectively. This leads expansive soil formation.

3.4.1Topography The region's topography embraces flat plains, gorges, plateaus, hills and mountains. The elevations of the study areas are Kemsie(1450)m ,Dessie (2470-2550)m, Debrebrhan(2750to2840)m,Woldiya(2112),Debremarkos(2000)m,Woreta(1828)m,Debret abor(2706)m,Gondar(2133)m,Merawi(2010)m,Bahirdar(1768-sebatamit- 1917zenzelema)m.The aspect of the slope affects the amount of water that moves through the soil. Fissures in the soil can also develop. These fissures help water to penetrate to deeper layers. This produces a cycle of shrinkage and swelling that causes the soil to undergo great amount of volume changes.

3.4.2 Drainage Characteristics of the Soils Surface drainage features, such as ponding around a poorly graded house foundation, provide sources of water at the surface; leaky plumbing can give the soil access to water at greater depth. The drainage around any engineering structure should always be “positive,” that is, all water falling near the structure should drain, or be channeled away from it. If it is allowed to stand, the water will percolate into the system of cracks in the moisture active zone.

3.4.3 Rain fall The rainfall in the region is characterized by alternation of wet and dry seasons in a periodic pattern.

The rain fall distribution in the areas of study is Kemisie(13.97-332.87)mm ,Dessie (283) mm,Debrebrhan(897.9)mm,Woldiya,Debremarkos(1308)mm,Woreta(1216.3)mm,Debreta bor(1528)mm,Gondar(1151)mm,Merawi (1627.9)mm,Bahirdar(1384)mm.

Seasonal changes in rainfall were typically the principal cause of the change of soil moisture. This led to downward movement during summer and upward movement during winter. The consequent rising and settling of ground surface occurred in the dry and wet seasons resulting in seasonal subsidence and seasonal recovery respectively.

3.4.4 Temperature Temperature directly influences the speed of chemical reaction. The warmer the temperatures the faster reaction occur. Fluctuation in temperature increases physical weathering of rocks, and then the formation of expansive soil increases with the increase of temperature. The temperatures in the areas are Kemisie(19.51-26.4)°C, Dessie(15.2)°C. Debrebrhan(12.9)°C,Woldiya(14)°C,Debremarkos(16)°C,Woreta(20.3)°C,Debretabor(24)° C,Gondar(19.3)°C,Merawi(13.73-20.78)°C,Bahirdar(17-23)°C.(metrology of Amhara region)

3.5 Expansive soil testing practice

Three methods are practiced for recognizing expansive soils in the region. Namely: (i) Mineralogical identification, (ii) Direct measurement, and (iii) Indirect methods. Mineralogical identification is important for exploring the basic properties of clays, but it is impractical and uneconomical for practicing engineers. The second one being the direct measurement is most useful but time consuming and laborious, involving the use of costly and elaborate testing equipment and trained personnel to conduct the experiments. Soil type and mineral type can be inferred by simple laboratory tests and field observations. The third group of methods falls under this category. Recognition of soil type, mineral type or composition provides a guide to the expected properties of that soil and selection of appropriate methods for improving behavior of soil (Adem Ebrahim 2014)

In some areas of Amhara region the researchers use the direct measurement for recognizing expansive soils. Because it is a convenient and more reliable test and directly tell the likely in situ response of the soil for moisture variations. Most of the researchers used the indirect methods.

3.6 Evaluation of Expansive soil Engineering Properties

3.6.1Visual identification Expansive soils have significant clay content, CL or CH and Dry expansive soils often have fissures, slickensides, or shattering .When dry, the soils have cracks at the ground surface.

3.6.2 Determination of degree of expansiveness

In most areas of Amhara region, the expansive soils are evaluated by the indirect measurement by examining other parameters, which indirectly give information about the soil property. These parameters are grain Size Analysis, atterberg limit and free swell tests are some, among the index property tests.

3.6.3 Index Properties of Expansive Soils

Index property helps in distinguishing the characteristics of a soil. Soil grain property and soil aggregate property are two main categories under this term. Soil grain property is based on the individual grains and depends on size, shape and mineralogical characteristics. Soil aggregate property, on the other hand is based on the property of the soil mass as a whole. Atterberg limit test, hydrometer analysis, specific gravity and free swell tests are among the tests which show the index properties of the soil. Shrinkage Limit is used also as a guide to the determination of potential expansiveness.

3.6.3.1Moisture Content Moisture content has an influence on the swelling potential of expansive soils. Natural moisture content of a soil is affected by climate, vegetation cover of the area and other artificial factors. Hence, the same soil could have different moisture contents in different seasons of a year and in different times. Since such type of moisture content is likely to

fluctuate any time it may not indicate the general property of the soil. The natural moisture content of different cities of Amhara region is studied by the following researchers.

Table 3:2moisture content values

No Sample No wn (%) Place Researcher 1 37 26.51-61.24 Bahir Dar DagmaweNegussie 2 22 58.8-94.24 Debre Tabor Belay Belete 3 20 17-52.9 Woreta Yonatan 4 12 15.87-52.3 Gondar Addis zemenTeklay 5 12 32.7-38.4 Merawi EyasuMinichle 6 18 25.2-49.6 Debremarkos AdemEbrahim 7 22 20.11-58.99 Debrebirhan Solomon Mebrahetu 8 12 24.2-31.7 Dessie TesfayeAlemnew 9 19 12.9-38.4 Kemisie Yimam Mohammed 10 8 28.5-31.72 Woldia TadesseAbebe

From table 3.1 Bahirdar,Debretabour and Gondar soils have higher moisture content whereas Woldiya ,Deremarkos and Kemsie soils have lower moisture content. The areas with higher moisture content have higher rainfall values this causes due to climate. This provides the range of moisture content of the region is 12.9 Kemisie-94.24 Debretabor.

3.6.3.2Grain Size Analysis Grain size divides soil into two distinctive groups, namely cohesion less and cohesive soil. Soil particles, which are coarser than 0.075 mm, are generally termed as cohesion less and the finer ones like silt and clay are considered fine grained.

Table 3:3Grain size distributions of some areas of Amhara region

City Percent amount of particle size Type of soil Rate as sub Sand (%) Silt (%) Clay (%) grade material Godar _ 16.45-56.53 41.6-82.3 clayey soil Poor Debre Tabor 0.49-14.38 15.87-44.66 44.98-82.71 clayey soil Poor Woreta 0.82-62.68 8.99-61.16 6.48-83 clayey soil Poor Bahir Dar 0.61-21.0 11.32-26.3 55.4-87 clayey soil Poor Merawi 0.5-10.54 7.85-35.07 72.35-91.26 clayey soil Poor Debremarkos 0.36-13.28 18.88-40.21 51.89-84.28 Silt clayeysoil Poor Debrebirhan 2.37-38.74 27-55.9 11.07-67.5 silt clayey soil Poor Dessie 2.1-16.55 18.28-46 51.3-70.71 clayey soil Poor Kemisie 1.4-54.42 39.33-65.96 11.07-57.16 silt soil Poor Woldia 2.42-18.65 41.6-62.98 6.16-49.25 silt soil Poor

From table 3.2 the soils with higher silt content have relatively low dry density and also low natural moisture. They quickly collapse and a high settlement occurs. Silt soils may vary from very hard compact and somewhat cemented siltstones capable of supporting heavy loads to very loose saturated silt deposits that in their natural state are not capable of supporting any structural load; in fact, they may, with time, consolidate under their own load. Like all soils, the higher the density the better will be the shear and compressibility characteristics.

Silts are the non-plastic fine soils. They are inherently unstable in the presence of water and, like fine sands, may become quick. Silts are semi pervious to impervious, often difficult to compact, are highly susceptible to frost heaving, and have low cohesive strength.

In normal foundation engineering, when saturation exists naturally or is contemplated by operation of the engineering works, loading of soft, compressible silt soils may be occurred by driving piles through them to firm underlying strata, preloading and draining to secure the desired consolidation and strength for the structure loads desired .Excavation and refill with select compacted soils is a third method often used when the compressible strata are not overly deep.

3.6.3.3 Atterberg limit Plastic index and liquid limits are important factors that help to understand the consistency or plasticity of clay. The soils in Woreta and Bahirdar has higher liquid limit than the others whereas Kemisie, Woldiya and Debrebrhan has lower liquid limit. This indicates Woreta and Bahirdar soils are highly plastic. In high-plasticity clays slope failures involves formation of surface cracks, moisture infiltration through the cracks into the soil mass, a reduction in suction and hence shearing resistance of the soil, and ultimately slope failure when the driving stresses exceed the shearing resistance of the soil. Similar processes can impact other earth structures such as retaining walls and pavements. The strength of high-plasticity clays will degrade due to climatic variations in moisture at the ground surface. Greater the liquid limit we will understand that greater is the compressibility of the soil.

Table 3:4Atterberg limit test results of Amhara region

Atterberg limit City Researcher LL (%) PL (%) PI (%) Bahir Dar 68.89-110.2 18.5-33.9 45.8-78.6 DagmaweNegussie Debre Tabor 67-97 37.59-43.24 42.57-37.59 Belay Belete Woreta 60-127 5.1-75 5.1-85 Yonatan Addis 75-106.09 21.41-44.48 44.55-75 Gondar zemenTeklay Merawi 52.3-67.8 24.5-33.4 27.8-39.4 EyasuMinichle Debremarkos 45-83 18-36 15-48 AdemEbrahim Solomon Debrebirhan 32-80 17-43 11.1-46 Mebrahetu Dessie 61-88 38-59 22-38 TesfayeAlemnew Yimam Kemisie 30.7-84.9 23.3-33.3 6.5-55.4 Mohammed Woldiya 34.11-96.63 28.62-33.78 9.33-66.55 TadesseAbebe

3.7 Damages Caused by Expansive soils in the region

Because of the different building loads on different portions of a structure's foundation, the resultant uplift will vary in different areas. This phenomenon can be exacerbated by moisture differentials within soils at the edge of the slab. Such differential movement of the foundation can also cause distress to the framing of a structure (Tibebu Solomon, 2015).

Buildings constructed on an expansive ground surface evaporation and temperature variations are retarded below it. As a result, patterns of soil movement under the building are identified on the basis of short-term and long-term effects. This soil movement will create the following foundation distresses a) Edge heave

In the short-term, i.e., just after the construction is complete, below the center of the building, moisture variation remains small while at the edges, seasonal moisture change continue to occur. If the building is constructed during the dry season, in the wet season that follows soil around the building absorbs rain water and swells pushing up the peripheral foundations. This effect is called the edge heave (C.Venkatramaiah, 2006). Edge heave can also be initiated due to local effects, such as, sprinkling of water for vegetation around building, leaking utility lines and ponding of surface water due to poor drainage system. In addition to moisture variation, edge heave can be initiated by effect of confinement of the foundation system. For example, the exterior corners of a uniformly- loaded rectangular slab foundation will only exert about one-fourth of the normal pressure on a swelling soil of that exerted at the central portion of the slab. As a result, the corners tend to be lifted up relative to the central portion (Rogers, J. D., R. Olshansky, and R. B. Rogers,). b) Edge shrinkage

Like edge heave, edge shrinkage is also a short-term effect. If the building is constructed during the wet season, in the dry season that follows, soil around the building loses the absorbed rain water and the soil leaves the peripheral foundations. This effect is called the edge shrinkage. Presence of big trees closed to building will also cause edge shrinkage. Especially during the dry season when moisture available for roots to suck is the least,

trees absorb water from the nearby foundation soil through their root system and cause shrinkage of soil. c) Cracks

The degree of damage based on observed cracks ranges from hairline cracks, severe cracks, very severe cracks to total collapse. The pattern of the cracks depends on whether it is a dooming heave or a dish shaped lift heave (Terzaghi, K., and Peck, R.B 1967). In both cases vertical, horizontal and/or diagonal cracks will be developed along walls and floor area. This intern has a great effect on functionality of doors and windows.

4 METHODOLOGY

4.1 GENERAL

In order to achieve the objective of this research, related researches which were done before were reviewed. Several data were taken from design office and from different theses that were done before on different places of Amhara region and from design offices.

4.1.1 Methodology of study Correlations between moisture content and liquid limit have done. Soils were characterized by their engineering properties.

Correlations of index properties and swelling pressure are done, (swelling vs. plastic index, swelling vs. moisture content, swelling vs. dry density, swelling vs. clay content). The parameter have been selected which better indicates swelling pressure.

The relations and new empirical equations obtained from statistical regression analysis (NCSS) between the swelling pressure and atterberg limits of local clay expansive soil. From the empirical model the swelling properties of the soils obtained. Finally, conclusion and recommendation are made. The flow chart indicates the generalized methodology of the research.

Problem identification

Data collection

Gathering data’s from design office Literature review

Gathering data’s from researches

Analysis and characterization of soils Analysis and characterization of soils

Statistical analysis

Develop correlations and models

Validate model

Finalize the model and characterize the soil

Figure 4:1Flow Chart of the Research Methodology

4.2 Data Collection and Analysis

4.2.1 Test Results The primary task of this research is gathering the data from different studies that were done before on different place of Amhara region. These places are Debretabor (Belay Belete, Relationship between index property and swelling characteristic of expansive soil in Debretabor,2014),Woldia(TadesseAbebe,investigation into some of the engineering properties of soil in Woldiya town,2014),Bahirdar(Dagmawe Negussie In depth investigation of relationship between index property and swelling characteristic of expansive soil in Bahirdar,2007 and FasilAbegazInvestigation into some of the

engineering properties of red clay soils in Bahirdar,2003,Tibebu SolomonAssessment of damages caused by expansive soil on buildings constructed in Bahirdar, thesis Addis Ababa university, 2015. ),Merawi(EyasuMinichle, Investigation Some of the Engineering Properties of Soil in Merawi Town.2015),Debremarkos(AdemEbrahim,Investigation into some of the engineering properties of soils in Debremarkos town2014,Gediyon Andualem Developing correlation between dynamic cone penetration index and undrained shear strength of Debremarkos soil,2015),Debrebirhan(SolomonMebrahetu,Investigation in to some of the engineering and index properties of soils found in DebreBirhan,2015),Dessie(TesfayeAlemnew,Index properties, shear strength and dynamic properties of soils found in Dessie),Kemssie(YimamMohammed,Investigations on some of the Engineering properties of soils found in Kemise town ,2015),Gondar(AddiszemenTeklay,On assessment of some of the engineering properties of soil in Gondar,2005),Woreta(Yonatan,Geotechnical Engineering properties of soils found in Woreta town ,2016).

4.2.2 Characterization of Expansive soils in some areas of Amhara region by some parameters The following table describes the summary range of test results of Amhara region soils.

Table 4:1 Summaries of test results

City Range of test results(%) Liquid limit Plastic Plastic index Free Moisture Specific Limit Swell content gravity Godar 68.89-110.2 18.5-33.9 45.8-78.6 82-107.5 15.87-52.3 2.6-2.83 Debre Tabor 67-97 37.59-43.24 42.57-37.59 70-145 58.8-94.24 2.5-2.82 Woreta 60-127 5.1-75 5.1-85 31.5-101 17-52.9 2.63-2.81 Bahir Dar 75-106.09 21.41-44.48 44.55-75 78-215 26.51-61.24 2.55-2.81 Merawi 52.3-67.8 24.5-33.4 27.8-39.4 15-20 32.7-38.4 2.7-2.76 Debremarkos 45-83 18-36 15-48 30-180 25.2-49.6 2.74-2.89 Debrebirhan 32-80 17-43 11.1-46 35-100 20.11-58.99 2.62-2.81 Dessie 61-88 38-59 22-38 65-130 24.2-31.7 2.65-2.83

Kemisie 30.7-84.9 23.3-33.3 6.5-55.4 15-97.5 12.9-38.4 2.6-2.74 Woldia 34.11-96.63 28.62-33.78 9.33-66.55 39-128 28.5-31.72 2.65-2.89

4.2.2.1 Activity number Skempton found that there is a correlation between the plasticity index of a soil and the proportion of particles of clay size in the soil. If a given specimen of clay soil is mixed with various proportions of silt soil.

Activity of the soil assesses capacity of soil to hold water. This is applicable for clayey soil. The swelling and shrinkage volume change depends on the activity of clay soil. Active soils have high swelling capacity.

The Activity number is given by the following equation.

plasticty Index,IP Activity = Percent of clay finer than 2 micron

Depending upon activity, the soils are classified into three types as given in Table

Figure 4:2 Mineral activities (AgusTugas S., M.Cakrawala, and Candra A., (2012))

Montmorilonnite has high swelling potential

Table 4:2Classification of soils based on activity

Activity Degree of Activity <0.75 Inactive clay 0.75-1.25 Normal clay >1.25 Active clay

City Activity= PI/C Degree of Activity Gondar 2.7-5.4 Active Debre Tabor 0.6-1.2 Normal clay Woreta 0.2-1.02 In active, some normal clay Bahir Dar 0.84-1.00 red clay soils In active, others normal clay Merawi 0.35-0.48 In active Debremarkos 0.21-0.68 In active Debrebirhan 0.6-1.25 In active Dessie 0.42-0.54 In active Kemisie 0.47.0.86 Normal ,semi in active Woldia 0.91-1.25 Normal clay

All most the soils are in active which have low swelling potential.

The activity of clay soil depends on the clay minerals which form the solid phase and the solute ions in the water (liquid phase).Debre tabor soils have higher swelling capacity from the other areas.

4.2.2.2 Consistency Consistency is a term used to indicate the degree of firmness of cohesive soils. The consistency of natural cohesive soil deposits is expressed qualitatively by such terms as very soft, soft, stiff, very stiff and hard. The physical properties of clays greatly different water contents.

Soil is very soft at a high per percentage of water content and very hard with a decrease in water content. However, it has been found that at the same water content, two samples of clay of different origins may possess different consistency. Clay may be relatively soft

while the other may be hard. Further, a decrease in water content may have little effect on one sample of clay but may transform the other sample from almost a liquid t o a very firm condition.

Table 4:3 Different states and consistency of soils with Atterberg limits

The consistency of undisturbed soil varies quantitatively on the basis of its liquidity index. Soils with lower liquidity index are hard soils whereas soils with higher liquidity index are soft soils.

Table 4:4 Soil consistencies based on the unconfined compressive strength

Consistency qu,kN/m2 Very soft 0-25 Soft 25-50 Medium 50-100 Stiff 100-200 Very stiff 200-400 Hard >400

City qu(kN/m2) Consistency Godar 210 Very stiff Debre Tabor 115 Stiff Woreta 100 Stiff Bahir Dar 76 Soft to stiff Merawi 100 soft to stiff clay Debremarkos 180 Stiff Debrebirhan 220 Stiff or Very stiff

Dessie 500 Hard Kemisie 125 stiff and hard Woldia 150 Stiff

Soil which is very soft has a high per percentage of water content and becomes very hard with a decrease in water content. Merawi and Bahirdar soils have high percentage of water and they are soft soils, whereas Dessie soils decrease water content are hard soils.

4.2.2.3 Degree of Expansiveness The degree of expansiveness of soils is determined by the swelling potential of the soil. Soils in Merawi and Kemisie are non-expansive soils whereas soils in the other areas are expansive soils. Almost the soils in the region are expansive soils they have high degree of swelling potential.

The free swell or differential free swell, also termed as free swell index, is one of the commonly used simple experiments performed by geotechnical engineers for getting estimates of soils expansion potential (Holtz and Gibbs, 1956).

Free Swell is the percentage of change in size within graduated tube with capacity 100 cm3 of water for a soil sample of 10 cm 3(vi) passing sieve size opened 0.425 mm. Leave the tube for 24 hours and record the final volume (vf). Where Vi, Vc is the size of the primary and final respectively.

(final volume−initial volume) Free swell value (%) = x 100 initial volume

Table 4:5 free swell range

F.s Classification < 50 % No problem 50 -100 % perhaps problem 100% Tests must be done on undisturbed samples

Table 4:6 Soils expansiveness

Free swell Degree of Expansiveness <50 Non expansive 50-100 Marginal >100 potentially expansive

City Free swell (%) Degree of Expansiveness Godar 82-107.5 Marginal Debre Tabor 70-145 Potentially expansive Woreta 31.5-100 expansive to marginal Bahir Dar 78-215 potentially expansive Merawi 15-20 Non expansive Debremarkos 30-180 Most areas non expansive Debrebirhan 35-100 Marginal Dessie 65-130 Marginal-potentially expansive Kemisie 15-97.5 Non expansive and marginal Woldia 39-128 Non expansive and expansive

4.2.2.4 Swelling Pressure/Potential The most common and supported methods of identifying the swelling potential and swelling pressure of plastic clay are direct measurement methods. One of the direct measurements used to assess the swelling soil behavior is use of conventional one dimensional consoledometer, which is referred as Free Swell Test or One dimensional Swelling Test. Methods for one- dimensional swell test and settlement potential of cohesive soil are explained in standard test ASTM D 4546-08.

4.2.2.5 Expansive Soil Swelling Potential Assessment

Expansive soils are classified basing on the term called potential expansion, also termed as potential swell or degree of expansion. Conventionally, Expansion Potential is expressed in terms Very High / High / Medium / Low degree of expansiveness.

Table 4:7 swelling properties of soils

Swelling potential PI Low 0-15 Medium 15-35 High 20-55 Very high >55

Table 4:8 swelling properties ofAmhara region soils

City Plastic index Swelling potential Godar 75 Very high Debre Tabor 37.59 Very high Woreta 85 Very high Bahir Dar 78.6 Very high Merawi 39.4 High Debremarkos 48 Medium Debrebirhan 46 Medium Dessie 38 Medium Kemisie 55.4 High Woldia 9.33-66.55 Low-very high

All the soils in the region have high expansive potential.

Studying swelling property is to measure the expansive potential of soil (AgusTugas S., M.Cakrawala, and Candra A., (2012),)

Table 4:9Typical Atterberg limits for soils.

Soil type Liquid limit Plastic Plastic index limit Sand Silt 30-40 20-25 10-15 Clay 40-150 25-50 15-100 Minerals contents Kaolinite 50-60 30-40 25-35 Illite 95-120 50-60 50-70 Montmorillonite 290-710 50-100 200-660

4.2.3 Classification of Expansive Soils There are different classification schemes, which use different basics for the purpose. Among these, the Unified Soil Classification System (USCS) and the American Association of state Highway and Transport official (AASHTO) method makes use of index property for classification.

4.2.2.6.1Unified soil classification system (USCS)

The basis for USCS (Unified Soil Classification System) is Liquid Limit and Plasticity Index of a soil. An “ A-line” which is defined by an equation (i,e, 0.73*(LL-20)) separates the ‘MH or OH’ and the ‘CH or OH’ designation.

Table 4:10 USCS of the soils of Amhara Region

City USCS Godar MH Debre Tabor CH Woreta MH,GM,SM Bahir Dar MH

Merawi MH Debremarkos MH,CH Debrebirhan CH,ML,SC,MH,CL,SH Dessie MH Kemisie ML,most MH Woldia MostCH,ML

Table 4:11engineering properties of the soils

City USCS Permeability Shearing Compressibility Workability when strength when when as compacted compacted and compacted and construction saturated saturated material Godar MH Semi Fair to poor High Poor pervious to impervious Debre Tabor CH Impervious Poor High Poor Woreta MH,GM,SM Semi Good Negligible Good pervious to impervious Bahir Dar MH Semi Fair to poor High Poor

pervious to impervious Merawi MH Semi Fair to poor High Poor pervious to impervious Debremarkos MH,CH Impervious Poor High Poor Debrebirhan CH,ML,SC,MH,CL,SH Impervious Good to fair Medium Good to Fair Dessie MH Semi Fair to poor High Poor pervious to impervious Kemisie ML,most MH Semi Fair to poor High Poor pervious to impervious Woldiya MostCH,ML Impervious Poor High Poor

According to this classification scheme most of the soils are classified under (MH) inorganic clays of high plasticity, fat clay .Debrebrhan and Woreta soils are preferable than the others as a construction material due to their good shear strength when compacted and saturated.

4.2.2.6.2AASHTO Soil Classification System The AASHTO system uses similar techniques but the dividing line has an equation of the form PI= LL-30. It generally classifies a soil broadly into granular material and silt-clay material. The granular material is further divided into three groups which are called A-1, A-2 and A-3. The silt-clay material is in turn divided in to four groups namely, A-4, A-5, A-6 and A-7.

The AASHTO soil classification system is used to determine the suitability of soils for earthworks, embankments, and roadbed materials (subgrade natural material below a constructed pavement; subbase layer of soil above the subgrade; and base a layer of soil above the subbase that offers high stability to distribute wheel loads).

Figure4:3Charts for use in AASHTO soil classification system

Classification of soils of the region

Table 4:12 AASHTO soil classification system

City AASHTO classification Godar A-7-5 Debre Tabor A-7-5 &A-7-6 Woreta A-7-5 &A-7-6,A-2-5&A-1-b Bahir Dar A-2-7,A-7-5,A-7-6 Merawi A-7-6 Debremarkos A-7-5 &A-7-6 Debrebirhan A-7-5 &A-7-6 Dessie A-7-5 Kemisie A-7-5 &A-7-6 Woldia A-7-5,A-4 Most soils are Silt-clay materials (Morethan35percent oftotalsamplepassingNo.20) and are fair to poor general rating as subgrade.

4.2.2.7Comparison of test results Liquid Limit (%)

Table 4:13 comparisons of the liquid limit values

Higher Liquid limit Lower Liquid limit Wereta Kemisie Bahirdar Debrebrhan Gonder Woldiya

No Sample No LL (%) Place Researcher 1 37 75-106.09 Bahir Dar DagmaweNegussie 2 22 67-97 Debre Tabor Belay Belete 3 20 60-127 Woreta Yonatan 4 12 68.89-110.2 Godar Addis zemenTeklay 5 12 52.3-67.8 Merawi EyasuMinichle 6 18 45-83 Debremarkos AdemEbrahim 7 22 32-80 Debrebirhan Solomon Mebrahetu 8 12 61-88 Dessie TesfayeAlemnew 9 19 30.7-84.9 Kemisie Yimam Mohammed 10 8 34.11-96.63 Woldia TadesseAbebe

Plastic index and liquid limits are important factors that help to understand the consistency or plasticity of clay.

The soils in Woreta and Bahirdar has higher liquid limit than the others where as Kemisie and, woldiya and Debrebrhan has lower liquid limit. This indicates woreta and Bahirdar soils are highly plastic. In high-plasticity clays slope failures involves formation of surface cracks, moisture infiltration through the cracks into the soil mass, a reduction in suction and hence shearing resistance of the soil, and ultimately slope failure when the driving stresses exceed the shearing resistance of the soil. Similar processes can impact other earth structures such as retaining walls and pavements. The strength of high-plasticity clays will degrade due to climatic variations in moisture at the ground surface. Greater the liquid limit we will understand that greater is the compressibility of the soil.

Plastic Limit (PL %)

Table 4:14 comparisons of the plastic limit values

No Sample No PL Place Researcher 1 37 21.41-44.48 Bahir Dar DagmaweNegussie 2 22 37.59-43.24 Debre Tabor Belay Belete 3 20 5.1-75 Woreta Yonatan 4 12 18.5-33.9 Godar Addis zemenTeklay 5 12 24.5-33.4 Merawi EyasuMinichle 6 18 18-36 Debremarkos AdemEbrahim 7 22 17-43 Debrebirhan Solomon Mebrahetu 8 12 38-59 Dessie TesfayeAlemnew 9 19 23.3-33.3 Kemisie Yimam Mohammed 10 8 28.62-33.78 Woldia TadesseAbebe

Woreta and Dessie soils have higher plastic limit whereas Gondar,Debremarkos and Debrebrhan soils has lower plastic limit. Soils with high plastic limit indicate increase the percentage of clay whereas the lower value indicates low percentage of clay.

Plastic Index (%)

Table 4:15 Comparison of the plastic index values

Higher plastic Index Lower plastic Index Woreta Kemisie Gondar Debremarkos Bahirdar Woldiya PI of soils depends on clay content of the soil.so soils with high plasticity index are considered to tend to clay. It is the measure of fineness of particles, PI increases with decrease in particle size. When plastic index increased permeability decreases whereas toughness and dry strength increased. Soils with higher plastic index are considered clay and those having lower value are considered silt. Lower plastic index soils are indicative to have high organic matter.

Then the soils in Woreta, Gondar and Bahirdar are clay soils and have lowerpermeability and higher toughness and dry strength whereas woldiya,Kemisie and Debremarkos are silt soils and have organic matter. And have higher permeability.

Specific gravity values (Gs)

Table4:16 Comparison of specific gravity values

Higher Specific gravity Lower Specific gravity Debremarkos Debre tabor Debrebrhan Bahirdar Woreta Kemisie Specific gravity is closelylinked with mineral and chemical composition and also reflects the history of weathering and useful in mineral classification.Higher value of specific gravity gives more strength for roads and foundation.Specific gravity increases the CBR value i.e. strength of sub grade material used in road construction. Then an area with higher specific gravity such as Debremarkos, Debrebrhan and Woreta have higher shear strength and has good sub grade materials comparatively from the other areas.

Free swell (%)

Table 4:17 comparison of the swelling pressure values

No Sample No FS Place Researcher 1 37 78-215 Bahir Dar DagmaweNegussie 2 22 70-145 Debre Tabor Belay Belete 3 20 31.5-101 Woreta Yonatan Addis 82-107.5 Godar 4 12 zemenTeklay 5 12 15-20 Merawi EyasuMinichle 6 18 30-180 Debremarkos AdemEbrahim Solomon 35-100 Debrebirhan 7 22 Mebrahetu 8 12 65-130 Dessie TesfayeAlemnew Yimam 15-97.5 Kemisie 9 19 Mohammed 10 8 39-128 Woldia TadesseAbebe

Bahirdar,Debre tabor and Dessie has higher Swelling pressure and also Merawi ,Debremarkos and Kemisie lower swelling pressure.

Table 4:18 comparison of the Natural moisture content values

Lower natural moisture content Higher natural moisture content

Bahirdar Woldiya Debre tabor Debremarkos Gondar Kemisie

Clay content (%)

Table4:19 comparison of clay content

Lowerclay content Higher Clay content

Bahirdar Woldiya Debre tabor Debrebrhan Debremarkos Kemisie

Silt (%)

Table4:20 comparison of silt content

Higher silt content Lower silt content Kemisie Bahirdar Debrebirhan Merawi Woldiya Woreta

The soils with higher silt content have relatively low dry density and also low natural moisture. They quickly collapse and a high settlement occurs. Silt soils may vary from very hard compact and somewhat cemented siltstones capable of supporting heavy loads to very loose saturated silt deposits that in their natural state are not capable of supporting any structural load; in fact, they may, with time, consolidate under their own load. Like all soils, the higher the density the better will be the shear and compressibility characteristics.

Silts are the non-plastic fine soils. They are inherently unstable in the presence of water and, like fine sands ,may become quick. Silts are semi pervious to impervious, often difficult to compact, are highly susceptible to frost heaving, and have low cohesive strength.

In normal foundation engineering, when saturation exists naturally or is contemplated by operation of the engineering works, loading of soft, compressible silt soils may be occurred by driving piles through them to firm underlying strata .preloading and draining to secure the desired consolidation and strength for the structure loads desired .Excavation and refill with select compacted soils is a third method often used when the compressible strata are not over deep.

4.3 Correlation of index properties and swelling pressure with index properties of soils in the study area

4.3.1 Introduction

In the previous sections all the necessary data’s of index properties and swelling pressure were analyzed and interpreted. The focus of this chapter will be on searching relationship between index property and index properties with swelling pressure of the expansive soils, So that the general trend of expansive soil potential expansiveness can be inferred.

4.3.2 Data used for Analysis The data used for this study is already summarized in the previous chapters. These data’s include moisture content, liquid limit, plastic limit, plastic index, swelling pressure, particle size distribution, free swell, specific gravity. The summary of the data has been presented in the table below for clarity.

Table 4:21Test results of particle size distribution sample No wn(%) Percent amount of particle size Place Researcher Sand (%) Silt (%) Clay (%) 37 26.51-61.2 0.61-21.0 11.32-26.3 55.4-87 Bahir Dar Dagmawe N. 22 58.8-94.24 0.49-14.38 15.87-44.66 44.98-82.71 Debre Tabor Belay Belete 20 17-52.9 0.82-62.68 8.99-61.16 6.48-83 Woreta Yonatan 12 15.87-52.3 16.45-56.53 41.6-82.3 Gondar Addis zemenTeklay 12 32.7-38.4 0.5-10.54 7.85-35.07 72.35-91.26 Merawi EyasuMinichle 18 25.2-49.6 0.36-13.28 18.88-40.21 51.89-84.28 Debremarkos AdemEbrahim 22 20.11-58.9 2.37-38.74 27-55.9 11.07-67.5 Debrebirhan Solomon Mebrahetu 12 24.2-31.7 2.1-16.55 18.28-46 51.3-70.71 Dessie TesfayeAlemnew 19 12.9-38.4 1.4-54.42 39.33-65.96 11.07-57.16 Kemisie Yimam M. 8 28.5-31.72 2.42-18.65 41.6-62.98 6.16-49.25 Woldiya TadesseAbebe

4.4 Relationship between Liquid limit and Moisture Content of Expansive soil of Amhara Region

One point liquid limit method has determined by using ASTM Test Designation D-4318 (LL= Wn (N/25) tanβwhere tanβ =0.12), which is driven from for soil of other locality

(OutsideEthiopia) (Standard Test Methods for Liquid Limit, Plastic Limit, and Plasticity Index of Soils).

LL= Wn (N/25) tan β…………………………………………………………………. (4.1)

Whereas for expansive clay soils of Ethiopia, tanβ =0.104 (Nardos Belete, 2015)

Where

LL -liquid limit

Wn = water content at N blows of the liquid limit device

tan β= slope of the flow line on a semi log plot (mean value for a given soil

The data’s in the table below are obtained from the areas listed (i.e.)Gondar ,DebreTabor,Woreta,BahirDar,Merawi,Debremarkos,Debrebirhan,Dessie,Kemisie,Woldia with the number of samples respectively listed in chapter four.

Table 4:22, 271 points of LL/Wn and N/25 data

Sr.No LL/Wn N/25 Sr.No LL/Wn N/25 Sr.No LL/Wn N/25 1 1.09 1.36 31 1.04 1.28 61 0.97 0.84 2 0.99 1.12 32 0.99 0.96 62 0.94 0.68 3 0.95 0.68 33 0.96 0.72 63 1.06 1.28 4 0.9 0.92 34 1.35 1.6 64 1 1.12 5 1 1 35 1.04 1.08 65 0.97 0.92 6 0.73 0.68 36 0.85 0.6 66 0.96 0.72 7 1.04 1.32 37 1.13 1.6 67 1.09 1.24 8 1.02 0.88 38 1.08 1.08 68 0.99 1.08 9 0.93 0.72 39 0.9 0.6 69 0.94 0.84 10 1.04 1.6 40 1.19 1.28 70 0.91 0.64 11 1 1.4 41 1 0.96 71 1.01 1.28 12 0.98 0.96 42 0.86 0.72 72 1 1.04 13 1.2 1.36 43 1.23 1.52 73 0.99 0.84 14 0.97 1.16 44 1.04 1.08 74 0.96 0.64 15 0.93 0.8 45 0.92 0.8 75 1.11 1.32 16 1.1 1.32 46 1.11 1.52 76 1.03 1.16 17 0.97 0.96 47 1.05 1.2 77 0.97 0.88 18 0.93 0.76 48 0.93 0.64 78 0.95 0.72 19 1.19 1.52 49 1.18 1.36 79 1.04 1.4 20 1.03 1.08 50 1.04 1.16 80 1.01 1.08 21 0.91 0.88 51 0.95 0.8 81 0.97 0.88 22 1 1.4 52 1.1 1.24 82 0.96 0.72 23 1.23 1.6 53 0.96 0.92 83 1.08 1.36 24 0.94 0.6 54 0.88 0.68 84 1.05 1.16 25 1.07 1.36 55 1.1 1.4 85 1.02 0.96 26 1 1.08 56 1.06 1.12 86 0.94 0.76 27 0.97 0.76 57 0.95 0.96 87 1.03 1.36 28 1.06 1.6 58 0.91 0.64 88 0.98 1.08 29 1.02 1.16 59 1.07 1.36 89 0.99 0.96 30 0.96 0.6 60 1 1.08 90 0.95 0.64 91 1.03 1.4 121 0.98 0.84 151 1.01 1.52 92 0.999 1.08 122 0.97 0.6 152 0.96 0.64 93 0.99 0.84 123 1.11 1.4 153 1 0.96 94 0.98 0.68 124 1 1.04 154 0.92 0.56 95 1.03 1.4 125 0.97 0.92 155 1.02 0.96

96 1 1.08 126 0.91 0.64 156 1.22 1.28 97 0.98 0.88 127 1.01 1.28 157 1.03 1.04 98 0.96 0.68 128 1.01 1.16 158 0.92 0.72 99 1.04 1.44 129 1 0.88 159 1.06 1.36 100 1.02 0.86 130 1 0.72 160 1.04 1.52 101 0.99 0.88 131 1.06 1.32 161 1 1.32 102 0.96 0.56 132 1.02 1.08 162 1 0.88 103 1.02 1.28 133 0.96 0.96 163 0.97 0.64 104 1 1.12 134 0.92 0.72 164 1.06 1.32 105 0.99 0.88 135 1.05 1.36 165 1 0.96 106 0.95 0.56 136 1.01 1.08 166 0.94 0.64 107 1.06 1.32 137 0.99 0.96 167 1.01 1.12 108 1.03 1.12 138 0.97 72 168 0.95 0.56 109 0.99 0.92 139 1.05 1.4 169 1.04 1.32 110 0.92 0.72 140 1.03 1.04 170 0.97 0.8 111 1.05 1.4 141 0.99 0.88 171 1.09 1.6 112 1 1.04 142 0.95 0.64 172 1.35 1.4 113 0.98 0.92 143 1.01 0.92 173 0.89 0.88 114 0.94 0.64 144 0.97 0.72 174 0.85 0.68 115 1.04 1.36 145 1.04 1.2 175 0.98 1.04 116 0.99 1.04 146 1.14 1.48 176 1.01 1.16 117 0.98 0.96 147 1.07 1.44 177 0.95 0.72 118 0.95 0.68 148 0.97 0.8 178 0.94 0.68 119 1.03 1.44 149 1.08 1.12 179 0.91 0.52 120 1.01 1.12 150 1 0.96 180 1.02 1.4 181 0.96 0.64 212 1.11 1.48 243 0.96 0.68 182 0.99 1.04 213 1.04 1.2 244 1.01 1.52 183 0.99 0.92 214 0.98 0.96 245 1 1.2 184 1.05 1.44 215 0.93 0.76 246 1 0.92 185 0.99 0.68 216 1.03 1.32 247 0.99 0.72 186 0.97 1.08 217 1.02 1.12 248 1.04 1.48 187 0.99 0.84 218 1.01 0.96 249 1.03 1.16 188 1.07 1.44 219 0.93 0.68 250 0.98 0.92 189 0.97 0.52 220 1.04 1.32 251 0.97 0.72 190 0.99 0.84 221 1 1.12 252 1.07 1.48 191 0.97 1.2 222 0.98 0.92 253 1.03 1.16 192 1.1 1.36 223 0.97 0.64 254 0.96 0.96 193 1.09 1.24 224 1.04 1.48 255 0.96 0.64 194 1.07 1.2 225 1.01 1.2 256 1.05 1.48 195 0.98 0.96 226 1 0.96 257 1.03 1.12 196 1.04 1.44 227 0.97 0.76 258 0.97 0.92

197 1.02 1.12 228 1.03 1.48 259 0.96 0.68 198 0.98 0.96 229 1.02 1.16 260 1.02 1.52 199 0.98 0.76 230 0.99 0.92 261 1 1.16 200 1.05 1.44 231 0.97 0.72 262 1 0.96 201 1 1.08 232 1.04 1.4 263 0.98 0.72 202 0.98 0.92 233 1.02 1.12 264 1.04 1.32 203 0.96 0.72 234 0.98 0.96 265 1 1.12 204 1.06 1.4 235 0.91 0.6 266 0.99 0.88 205 0.99 1.12 236 1.03 1.48 267 0.95 0.68 206 0.98 0.96 237 1.01 1.16 268 1.06 1.4 207 0.98 0.72 238 0.99 0.96 269 1.02 1.16 208 1.05 1.32 239 0.98 0.76 270 0.98 0.88 209 1.01 1.04 240 1.03 1.44 271 0.93 0.64 210 0.988 0.92 241 1.01 1.08 211 0.94 0.72 242 0.99 0.88

Based on the above data a scatter diagram is generated by applying the Excel Spreadsheet. In order to study the relationships develop between the dependent variable (LL/Wn) and the independent variable (N/25) so as to determine the model that best suit the data. 1.6 y = 1.0032x0.173 1.4 R² = 0.8398

1.2

0.8 LL/Wn 0.6

0.4

0.2

0 0 0.2 0.4 0.6 0.8 1 1.2 1.4 1.6 1.8 N/25

Figure 4:4Scatter plot of N/25 Vs LL/Wn

The scatter diagram provides visual method of displaying a relationship between the variables. The above scatter diagram was produced by making use of the excel spreadsheet, by selecting dot diagrams of the (N/25) and (LL/Wn) making it easy to see the distributions of the individual variables. Inspection of the above scatter diagrams indicate that, although no simple curve will pass exactly through all the points, there is a reasonable indication that the points are randomly scattered in exponential pattern. Thus, from the above scatter plot, it can be construed that a linear correlation does not exist between the dependent and the independent variable. For this research, the relationship between the dependent and independent variables, based on the above discussions and results of past studies is approximated by power regression models of the following form regression analysis.

The statistical software called NCSS has been employed to the study the relation between the repressor variable and the response to be predicted and the analysis is presented in section. Accordingly, the following result is observed.

The value of tanβ is 0.173, hence

Y=a*Xtanβ

Y= a*X0.173

The details of the output of NCSS software analysis have also been shown in the table below.

Table 4:23output of NCSS software

R R Square Adj R2 Std. Error of the Estimate .839 .827 .831 .01898 Through the power regression models of the following result is observed

Y=1.0032*X0.173 , (N=271)

Where Y=LL/Wn and X=N/25 , 1.0032≈1

LL/Wn=1(N/25)0.173, LL=Wn*(N/25)0.173…………………………………… (4.2)

If we compare the value of the required exponent tanβ obtained from Average value method and linear regression method, the different is 0.00 for Amhara region expansive soils it is to be insignificant. Hence, the value of tanβ is 0.173 for Amhara region.

4.5 Relationship between moisture content with liquid limit, plastic index and dry density

퐿퐿 = 0.566푟푑 + 0.99푃퐿 + 0.9939푃퐼 − 0.0017푊푛

Analysis of variance Sum of Mean Prob Power Source DF R² Squares Square F-Ratio Level -5% Model 4 1 720.9232 720.9232 215734.2 0 1 Error 43 0 9097.363 9097.363 Total 47 1 294494.1 6265.832

The data’s are not in the normal distributing because the points are no on the straight line.

4.6 Relationship between Swelling Pressure and Index Property

Relationships between Swelling Pressure and different parameters of index properties have also been investigated.

Bahirdar soils

600

500

400

300

200 Swelling Swelling pressure 100

0 0 10 20 30 40 50 60 70 80 90 Plastic index

Figure 4:5 Correlation swelling pressure with plastic index

600

500 y = 944446x-2.308 R² = 0.8248 400

300

200 Swelling Swelling pressure (Kpa) 100

0 0 10 20 30 40 50 60 70 water content (%)

Figure 4:6 Correlation swelling pressure with water content

600

500 )

400

300

200 swelling pressure(Kpa swelling 100

0 0 0.2 0.4 0.6 0.8 1 1.2 1.4 1.6

dry density (gm/cc)

Figure 4:7 Correlation swelling pressure with dry density in Bahirdar

Debretabour

600

500

400

300

200

swelling swelling pressure (Kpa) 100

0 0 10 20 30 40 50 60 70 plastic index(%)

Figure 4:8 Correlation swelling pressure with plastic index

600 -1.179 500 y = 19970x

R² = 0.78 (Kpa) 400

300 pressure 200

100 swelling swelling 0 0 10 20 30 40 50 60 70 moisture content(%)

Figure 4:9 Correlation swelling pressure with moisture content

600 ) y = 116.79x3.8256 500 R² = 0.772 400 300

pressure(Kpa 200 100

swelling 0 0 0.2 0.4 0.6 0.8 1 1.2 1.4 1.6 dry density(gm/cc)

Figure 4:10 Correlation swelling pressure with dry density

4.8.2 Statistically Analysis Linear and non Linear multiple Regression Analysis

4.8.2.1 Linear and non Linear Multiple Regression Analysis

Regression analysis divided into either linear regression or multiple regression analysis pertinent to the number of variables involved in the system. A regression model that contains more than one regressor variable is called multiple regression models. Alternatively, a regression model containing one independent variable or regressor is termed as linear regression model.

4.8.2.2 Statistically goodness of fit measures

The development and subsequent Fitting of a regression model requires many assumptions. Estimation of the model parameters requires the assumption that, the

residuals (actual values less estimated values) corresponding to different observations are uncorrelated random variables with zero mean and constant variance. Tests of hypotheses and interval estimation require that the errors be normally distributed. In addition, we assume that the order of the model is correct; that is, if we fit a simple linear regression model, we are assuming that the phenomenon actually behaves in a linear or first order manner. This is indeed fundamental assumption of any tests of hypothesis and interval estimation. (Nardos Belete,2015)

5 RESULTS AND DISCUSSION

5.1 Swelling Pressure vs. Plasticity Index

The swelling Pressure and Plasticity index for Bahirdar and Debre tabour soils shows there is a tendency of increment in the swelling pressure as the plasticity index increases. And also the widely scattered points do not follow the trend line; this shows the relationship is not strong. This indicates the determination of the Plasticity Index alone cannot satisfactorily indicate the swelling behavior of the soil addition of other index parameters is necessary.

5.2 Swelling Pressure vs. Natural Moisture Content

The effect of moisture content for the study areas has different values. The graph is plotted to show how it affects the swelling pressure of the study area. The results show a general trend of decreasing swelling pressure with increment of natural moisture content manifested in a non-linear relation. And also the widely scattered points follow the trend line; this shows that the relationship is strong. This implies the determination of the moisture content satisfactorily indicate the swelling behavior of the soil addition of other index parameters is necessary.

5.3 Swelling Pressure vs. Dry Density

Dry density, which is a measure of the compactness of soil grains, is also another factor, which plays a role in swelling characteristic of expansive soils. A graph is plotted to see the relationship between the dry density and swelling pressure of the study area. In Bahirdar and Debretabour the result shows that there is a tendency of increment of swelling pressure as the dry density increases.

5.4 Development of swelling pressure Predictive model from index properties of expansive soils

The models comprise different soil parameters in different combinations. Index properties were widely used parameters in these models because these properties have significance in indicating the swelling behavior of soil. Various graphs are drawn to show the relationship between the swelling pressure and index property values. Finally multiple regression analysis is performed to correlate the swelling pressure with these different index properties.

5.4.1 Data used for model development

The different soil parameters used for the model development are the swelling pressure and the index properties (Liquid limit, plastic limit, plastic index, moisture content, dry density).since the swelling pressure of the soils are not studied except Bahirdar and Debretabour.

In developing of such models I have used the multiple regression analysis, it contains more than one regressor variable. The equations obtained from the multiple regression analysis are more indicator the measured and calculated swelling pressure values than equations of linear regression model.

5.5 Models Developed by Various Researchers

There are different empirical equations developed to determine the swelling behavior of a soil.

Daniel Teklu

퐿표푔푆푝 = −9.384 − 0.0063 ∗ 푃퐼 + 0.00836훾푑푟푦 + 0.02748휔푛 … . … (5.1)

Sp-swelling pressure, PI-Plastic index and wn-moisture content,

훾푑푟푦 − 푑푟푦 푑푒푛푠푖푡푦

Komornik and David (1969)

퐿표푔푆푝 = −2.132 + 0.665훾푑푟푦 + 0.0208퐿퐿 + 0.0269휔푛 … … … … … (5.2)

Where LL-Liquid limit, 훾푑푟푦 − 푑푟푦 푑푒푛푠푖푡푦 ,wn-moisture content

DagmaweNegussie

푆푝 = 7.018 − 1.924훾푑푟푦 − 0.042푤푛 + 0.003퐶퐸퐶 … … … … … … … … … … … … … … (5.3)

Where CEC-cation exchange capacity

훶dry-dry density

ωn- moisture content

Sp-swelling pressure

5.6 Evaluation of previous models for the soils in the study area

Table 5:1Comparison of Previously Developed Equations with the Measured Value

Measured value Proposed equation(Kpa) swelling pressure(Kpa) Komornik and David Daniel Teklu DagmawiNigusse 547.52 145.57 450.58 741.82 344.58 164.18 310.90 269.64 111.82 58.03 310.9 103.79 514.61 359.75 574.67 528.74 175.38 84.35 223.45 204.33 165.6 50.7 1,183.81 162.18 377.27 65.45 112.35 256.59 79.95 24.06 22.11 389.86 379.24 124.46 1,998.23 447.46 538.33 93.53 470.21 209.47 202.27 56.12 513.91 265.76 296.91 63.01 1,088.68 170.42 135.74 61.59 1,128.99 238.03 197.41 135.7 1,031.10 282.6 264.76 100.71 1,660.31 165.48 114.37 68.02 506.32 387.14 495.81 58.77 334.41 166.12

186.8 76.15 266.82 279.24 298.11 14.48 17.24 198.33 326.44 49.73 115.11 192.39 140.64 55.96 115.11 168.13 79.95 56.3 1,578.27 49.13 92.12 44.21 926.03 181.4 128.09 28.41 89.96 157.04

From the above table it can be concluded that, none of the models are not applicable to predict the swelling pressure of the study area.

5.7 Development of Empirical Equations

Several equations composed of different parameters in different combinations were developed. These equations developed by NCSS computer program.

Out of these, equations with higher R2 values and related value (estimated and measured) were selected and using these equations the swelling behavior of the soil of the area were calculated. Then a graph is plotted which shows the measured value against the predicted or calculated value. Finally equations are selected which predicted the measured value better than the others. This is done using a multiple regression analysis.

1. Bahirdar soils swelling model

푆푝 = 531 − 12.7푤푛 + 7.05푃퐼 − 318훾푑푟푦 + 0.8퐿퐿 … … … … … … … . .5.4 푅2 = 0.838, 퐴푑푗 푅2 = 0.893, 푛 = 15

Sp = 418 − 14.1푤푛 − 108.3훾푑푟푦 − 5.21퐿퐿 … … … … … … … … … … … .5.5

푅2 = 0.86, 퐴푑푗 푅2 = 0.78, 푛 = 15

푔푚 Where: 훾푑푟푦 = 푑푟푦 푑푒푛푠푖푡푦 ( , ) 푠푝 = 푠푤푒푙푙푖푛푔 푝푟푒푠푠푢푟푒( 퐾푝푎), 푎푛푑 퐹푆, 푐푐 퐿퐿, 푃퐿, 휔푛, = %, 퐶 = 푐푙푎푦%, 퐴 = 퐴푐푡푖푣푖푡푦

Table 5:2 Comparison of Measured value with Calculated Value (Dagmawi Niguse 2007)

S. No Measured value(kPa) Calculated value(kPa) eqn 1 Calculated value(kPa) eqn 2 1 547.52 493.48 424.38

2 344.5 350.23 403.17

3 111.82 166.74 170.06

4 514.61 514.83 509.17

5 175.38 223.09 235.52

6 165.6 175.14 218.93

7 377.27 357.31 250.77

8 79.95 90.20 71.10

9 379.24 406.09 379.31

10 538.33 528.10 336.41

11 202.27 244.72 228.95

12 296.91 270.31 270.65

13 135.74 189.26 213.88

14 197.41 249.32 359.68

15 264.76 284.81 329.31

Measured value(kPa) Calculated value(kPa) eqn 1 Calculated value(kPa) eqn 2 114.37 110.2 98.5 495.81 455.6 450.6 186.8 202.7 199.6 298.11 307 311.4 210.22 182.6 201 326.44 352.7 366.4 140.64 142.3 168.5 92.12 98.1 110.2 128.09 125.9 112

The equations are valid for the entire data

2. Debre tabor soil swelling model 푆푝 = 1013.7 − 9.16푤푛 − 2.9푃퐼 − 0.7퐹푆 − 1.08퐿퐿 … … … … … … … … .5.6

푅2 = 0.844, 퐴푑푗 푅2 = 0.81 , 푛 = 20

Where; Sp=swelling pressure, wn=moisture content, PI=plastic index,

FS=free swell, LL=liquid limit

푆푝 = 945 − 9.45푤푛 − 3.85푃퐼 − 0.7퐿퐿 … … … … … … … … . . … … … … … … … … … … 5.7 푅2 = 0.82, 퐴푑푗 푅2 = 0.74 , 푛 = 20

Where: Sp=swelling pressure, wn=moisture content, PI=plastic index,

LL=liquid limit

Table 5:3 Debre tabor swelling pressure (Belay Belete 2014)

Calculated value(kPa) Calculated value(kPa) S. No Measured value(kPa) equation 1 equation 1 1 420 377.89 357.06 2 490 470.11 457.68 3 420 338.18 333.61 4 80 143.02 145.80 5 390 379.25 387.78 6 440 424.39 432.42 7 320 294.06 291.25 8 270 167.82 167.72 9 180 293.41 303.69 10 150 215.01 214.10 11 290 365.27 374.58 12 275 239.74 239.36 13 280 341.07 334.19 14 120 121.33 114.31 15 175 266.22 280.93 16 160 260.27 246.80 17 310 268.72 251.16 18 360 216.63 239.02 19 260 258.89 261.35 20 360 308.73 317.18

Table 5:4 checking of validation of the equations for control points Debre tabor soils

Measured Calculated value(kPa) Calculated value(kPa) eqn 2 value(kPa) eqn 1 240 239.58 251.27 250 246.46 263.6

5.8 Graphical Representation of the Measured and Calculated Values

The graphical representation indicates the accuracy of the newly developed formulas. The measured and calculated values are plotted (figure 5.1to figure 5.7) trend lines are drawn to observe the gap between the measured and the calculated values.

600

500 y = 0.8503x + 57.352 400 R² = 0.8906

300

200

100

0 Calculated swelling pressure(kPa) Calculated swelling 0 100 200 300 400 500 600 Measured swelling pressure(kPa)

Figure 5:1 Bahirdar soils Equation 1 vs. measured value

600

500 y = 0.5789x + 126.26 400 R² = 0.8478

300

200

100

0 0 100 200 300 400 500 600 Measured swelling pressure(kPa) Calculated swelling pressure(kPa) Calculated swelling

Figure 5:2 Bahirdar soils Equation 2 vs. measured value

600

500

400 predicted value measured value 300 calculated control point

200 measured control point Swelling pressure(kPa) Swelling 100

Figure 5:3Validation of equation 1 for Bahir dar soils

500

) 450 y = 0.6244x + 107.99 400 R² = 0.8344 350 300 250 200 150 100

Calculated swelling pressure(kPa Calculated swelling 50 0 0 100 200 300 400 500 600 Measured swelling pressure (kPa)

Figure 5:4 Debre tabor soils Equation 1 vs. measured value

500 450 y = 0.6152x + 110.64 R² = 0.8152 400 350 300 250 200 150 100 50 0 Calculated swelling pressure(kPa) Calculated swelling 0 100 200 300 400 500 600 Measured swelling pressure(kPa)

Figure 5:5 Debre tabor soils Equation 2 Vs measured value

600

500

400 predicted value measured value 300 calculated control point

200 measured control point Swelling Swelling pressure(kPa) 100

Figure5:6 Validation of equation 1 for Debretabor soils

From the graphs of measured and calculated values of swelling pressure, Equations developed for Debre tabor, Equations 1 and 2 gave a better estimation of the measured swelling pressure with the coefficient of determination of 0.84 and 0.82 respectively and equation one is valid for the entire data. Where as in Bahirdar Equations 1and 2 gave a better estimation of the measured swelling pressure with the coefficient of determination of 0.83 and 0.86 respectively.

5.9 Prediction of Swelling Pressure for the study area

푆푝 = 52.3 − 67푃퐼 − 271.5퐶 + 0.5퐹푆 − 0.17푤푛 … … … … … … … … .5.8

Where 푆푝 = 푠푤푒푙푙푖푛푔 푝푟푒푠푠푢푟푒, 퐹푠 − 푓푟푒푒 푠푤푒푙푙, 푐 − 푐푙푎푦, 푤푛 − 푚표푖푠푡푢푟푒 푐표푛푡푒푛푡 푃퐼 = 푝푙푎푠푡푖푐 푖푛푑푒푥

Table 5:5Analysis of variance of Amhara region

Analysis of variance Sum of Mean Prob Power Source DF R² Squares Square F-Ratio Level -5% Intercept 1 1436372 1436372 Model 4 0.9995 377835.1 37785.77 91.164 0.000 1.000 Error 12 0.0005 37577.52 3131.46

Total(Adjusted) 17 1 415412.6 25963.29

Measured, Predicted Values with Prediction Limits of swelling Pressure using Model 1obtained in Multiple Regression Subset Selection analysis

Table 5:6Predicted Values with Prediction Limits of swelling Pressure

Row 95% Lower 95% Upper standard Lower Upper Actual Predicted Error of Pred. Limit Pred. Limit Swelling pressure Swelling pressure Predicted of Individual of Individual 1 547.52 545.1973 2.572087 539.5932 550.8014 2 344.5 347.0527 2.358309 341.9144 352.191 3 111.82 112.7724 2.488427 107.3506 118.1942 4 514.61 514.3791 2.446142 509.0494 519.7087 5 175.38 172.6271 2.340874 167.5268 177.7275 6 165.6 163.0035 2.336477 157.9127 168.0942 7 377.27 378.6514 2.710505 372.7457 384.5571 8 79.95 79.81301 3.088685 73.08334 86.54268 9 379.24 381.9831 2.463296 376.6161 387.3502 10 538.33 537.0228 2.492942 531.5912 542.4545 11 202.27 200.0665 2.34713 194.9525 205.1804 12 296.91 298.1983 2.357548 293.0616 303.335 13 135.74 135.8199 2.432797 130.5193 141.1205 14 197.41 195.826 2.428256 190.5353 201.1167 15 264.76 265.0476 2.38705 259.8467 270.2486 16 114.37 117.5341 2.606452 111.8551 123.2131 17 495.81 496.4951 2.529804 490.9832 502.0071

600 y = 0.9999x + 0.0405 500 R² = 0.9999

400

300

200

100

Predicted swelling pressure(kpa) Predicted swelling 0 0 100 200 300 400 500 600 Measured swelling pressure (kPa)

Figure 5:7 Normality of and predicted and calculated swelling pressures

Swelling pressure with intercept

푆푝 = 63.3 − 240.52퐿퐿 + 126.96푤푛 + 2.65퐴 … … … … … … … … . .5.9

Where: 푠푝 = 푠푤푒푙푙푖푛푔 푝푟푒푠푠푢푟푒, 퐿퐿 = 푙푖푞푢푖푑 푙푖푚푖푡, 푤푛 = 푚푖표푠푡푢푟푒 푐표푛푡푒푛푡, 퐴 = 푎푐푡푖푣푖푡푦

Table 5:7Analyses Of Variance

Analysis of variance Source DF R² Sum of Mean F-Ratio Prob Power Squares Square Level -5% Model 3 0.9902 1861566 108928 93.225 0.000 1.000 Error 13 0.0098 123821 123821 Total 17 1 102606.3 102606.3 Measured, Predicted Values with Prediction Limits of swelling Pressure using Model1obtained in Multiple Regression subset Selection analysis

Table 5:8Predicted Values with Prediction Limits of swelling Pressure eqn 2

Row Actual Predicted Standard Error 95% Lower Pred. 95% Upper of Predicted Limit of Pred. Limit Individual of Individual 1 547.52 545.6926 3.6374 537.8344 553.5507 2 344.5 347.8158 3.307278 340.6708 354.9607 3 111.82 110.1236 3.269222 103.0609 117.1863 4 514.61 514.6803 3.440173 507.2483 522.1124 5 175.38 175.4527 4.047423 166.7087 184.1966 6 165.6 160.5407 3.48192 153.0185 168.063 7 377.27 378.3307 3.759576 370.2087 386.4528 8 79.95 85.09585 3.260561 78.05183 92.13986 9 379.24 384.5912 3.281879 377.5011 391.6812 10 538.33 535.7847 3.455865 528.3187 543.2506 11 202.27 200.2366 3.267593 193.1774 207.2958 12 296.91 299.0609 3.255275 292.0283 306.0935 13 135.74 134.0167 3.343461 126.7936 141.2398 14 197.41 196.4988 3.303637 189.3617 203.6358 15 264.76 266.1473 3.256904 259.1111 273.1834 16 114.37 113.3357 3.386646 106.0193 120.6521 17 495.81 494.1557 3.451317 486.6996 501.6118

600 y = 0.9997x + 0.1049 500 R² = 0.9997

400

300

200 pridicted value pridicted

100

0 0 100 200 300 400 500 600 Measured swelling pressure(kPa)

Figure 5:8 Normality plot and predicted and calculated swelling pressures

√푆푃 = 572.5 + 푂. 8881푤푛 − 0.014푃퐼 − 15.53푟푑 … … … … … … … … . . (5.9)

Where Sp-swelling pressure- Clay (%), wn-moisture content

PI-plastic index and rd=dry density

Analysis of variance Sum of Mean Prob Power Source DF R² Squares Square F-Ratio Level -5% Model 2 0.9994 1328.73 1328.73 81.476 0 1 Error 13 0.0046 22.5014 1.730877 Total 17 1 4941.49 290.6759

Measured, Predicted Values with Prediction Limits of swelling Pressure using Model3 obtained in Multiple Regression Subset Selection analysis

Table 5:9 Measured, Predicted Values with Prediction Limits of swelling Pressure

Row Actual Predicted Standard 95% Lower 95% Upper SP SP Error of Pred. Limit Pred. Limit Predicted of of Individual Individual 2 23.40 20.85 1.860579 19.37961 27.41868 3 18.56 16.60 1.393737 13.58633 19.6083

4 10.57 9.80 1.421991 5.724144 11.86819 5 22.69 22.67 1.560519 19.3009 26.04349 6 13.24 13.37 1.429496 10.28604 16.46252 7 12.87 12.99 1.531698 9.678297 16.29636 8 19.42 19.66 1.537104 16.34348 22.9849 9 8.94 10.47 1.353095 7.543054 13.38942 10 19.47 20.28 1.383347 17.29016 23.26724 11 23.20 21.70 1.438259 18.59388 24.80822 12 14.22 14.64 1.353233 11.71779 17.56476 13 17.23 18.03 1.429584 14.9462 21.12306 14 11.65 10.81 1.450988 7.675838 13.94518 15 14.05 16.03 1.387319 13.0329 19.02714 16 16.27 16.41 1.396374 13.3939 19.42726 17 10.69 12.45 1.365313 9.502734 15.40189

25 y = 0.8572x + 2.3061 R² = 0.9316 20

10 Predicted Predicted value

0 0 5 10 15 20 25

Measured swelling pressure

Figure 5:9 Normality plot predicted and calculated swelling pressures

Results of the Control Samples

Table 5:10 Comparison of Measured value with Calculated Value for Control Samples

Measured Calculated value(kPa) Calculated value(kPa) eqn 2 value(kPa) eqn 1 114.37 124.18 108.46 495.81 426.64 492.59 186.8 181.33 119.87 298.11 253.73 199.00 210.22 222.60 195.21 326.44 331.19 268.26 140.64 131.28 170.63 92.12 109.86 87.62 128.09 133.31 116.19 240 224.84 237.02 250 240.28 267.74

600

500

400 predicted value

300 measured value calculated control point

200 measured control point swelling pressure (kPa) pressure swelling 100

0 0 5 10 15

Figure 5:10 validation graphs equation 1

In the above graphs the predicted values overlap with the measured values, and also the control points have related values. This indicates the equations are valid for the remaining data (control points).

Among the equations developed by the regression model equation 1 has selected due to the fact that R2=0.9995, MSE (error) =0.0005 and this equation is valid for the control points.

6 CONCLUSIONS AND RECOMMENDATIONS

6.1 Conclusions

1. Expansive soils occur in most areas of the region in humid environments where problems occur with these soils which have high plasticity index can cause significant damage. The soils in Woreta, Gondar and Bahirdar are high plasticity expansive clay soils and have lower permeability and higher toughness and dry strength whereas woldiya, Kemisie and Debremarkos are silt soils and have organic matter with higher permeability. 2. Based on the experimental results obtained from different areas correlations and new empirical equations are done. The swelling pressure developed in a soil is inversely proportional to the initial moisture content and directly proportional to the dry density. 3. The Regression Analysis showed that there is a relationship between Index Properties and swelling characteristics of Expansive Soil of in some areas of study. The newly developed equations could be used for estimation of swelling characteristic of the soils study Area. 4. The equations with higher coefficient of estimation used for the estimation of the swelling pressure of the study areas alternatively. 5. The Regression Analysis showed that there is weak relationship between some Index Properties and swelling characteristics of Soil; some index properties do not indicate the swelling pressure. It is possible to control the amount of expansion in compacted clay soils by increasing the initial moisture content and/or decreasing the initial dry density. The swelling index and the clay fraction, give a better indication of the basic expansive characteristics of a soil. Good correlation obtained between liquid limit and moisture content from validation of one point liquid limit test.

6.2 Recommendations

1. Foundations on expansive soils must be designed and constructed with the necessary detail investigations so that the damage could be minimized. 2. Expansiveness is recommended to investigate the swelling pressure in other areas of the region. 3. The dynamic properties of the soil in most of the areas are not studied. Therefore, it needs investigation in the future to know the strength of the soils. 4. It is recommended that researches must be done for the areas which engineering properties of the soils have not been studied before. 5. The swelling pressure of Amhara region is not studied except Bahirdar and Debretabour. Hence, it is advisable to conduct index tests and develop correlation to predict swelling pressure. 6. It is recommended that tests should be carried out to measure the swelling pressures developed in undisturbed and disturbed soil samples at various values of initial dry density and initial moisture content, after allowing the sample to expand vertically to predetermined values.

REFERENCES

AdemEbrahim “Investigation into some of the engineering propertiesof soils in Debremarkos town”, M.sc, thesis Addis Ababa university, Addis Ababa July, 2014 AgusTugas S., M.Cakrawala, and Candra A., (2012), The effect of water contents on free swelling of expansive soil, International Journal of civil and environmental engineering IJCEE-IJENS Vol:12 No:06, Civil Engineering Department, University of Widyagama Malang, East Java, Indonesia. Ayenew, Z., 2004, Investigation into Shear Strength Characteristics of Expansive Soil Ethiopia, Unpublished M.Sc Thesis, Addis Ababa University. AddiszemenTeklay“On assessment of some of the Engineering properties of soil in Gondar”, thesis Addis Ababa university, 2005 Belay Belete “Relationship between index property and swelling characteristic of expansive soil in Debretabor”M.sc, thesis Bahirdar university ,Bahirdar, July 2014 Dagmawe Negussie” In depth investigation of relationship between index property and swelling characteristic of expansive soil in Bahirdar”, M.sc, thesis AddisAbaba university, Addis Ababa, February 2007 EyasuMinichle” Investigation Some of the Engineering Properties of Soil in Merawi Town”, M.sc ,thesis Addis Ababa university , February 2015 FasilAbagena“Investigation into some of the engineering properties of red clay soils in bahirdar”, M.sc, thesis Addis Ababa university, November 2003 Gedeyon Andualem“Developing correlationbetween dynamic cone penetration index and undrained shear strength of Debremarkossoil”,M.sc ,thesis Addis Ababa university ,November, 2015 (Gromko, 1974; Hunt, 1984; Hunter, 1988; Murphy, 2010): Solomon Mebrahetu ‘Investigation in to some of the engineering and index properties of soils found in DebreBirhan“, M.sc, thesis Addis Ababa university, town, Oct, 2015 Tadesse Abebe“Investigation into some of the engineering properties of soilinWoldiya town”, M.sc, thesis Addis Ababa university2014 Tesfaye Alemnew“Index properties, shear strength and dynamic properties of soils found in Dessie”, M.sc ,thesis Addis Ababa university , Addis Ababa, Tibebu Solomon “Assessment of damages caused by expansive soil on buildings constructed in Bahirdar”, M.sc, thesis Addis Ababa university, Addis Ababa December, 2015

Nardos Belete “Evaluation of one point liquid limit test for expansive clay soils of Ethiopia”,Msc thesis Addis Ababa,November, 2015 Standard Test Methods for Liquid Limit, Plastic Limit, and Plasticity Index of Soils Rogers, J. D., R. Olshansky, and R. B. Rogers, Journals “Damage to foundations from expansive Soils” Woldeamlak Bewket1 Rainfall variability Ethiopia Case study in the Amhara region Yonatan “Geotechnical Engineering properties of soils found in Woretatown“M.sc, thesis Bahirdar university, Bahirdar,July 2016 Yimam Mohammed “Investigations on some of the Engineering properties of soils found in Kemise town”, M.sc, thesis Addis Ababa, August, 2016 Komornik and David (1969)

Daniel T. (2003), Examining the Swelling Pressure of Addis Ababa Expansive

Soil, Unpublished M.Sc Thesis, Addis Ababa University.

APPENDIX-A Test results of researches Debremarkos

Debremarkos soil test result Serial Designation Depth Liquid Plastic Plastic Free OMC% MDD No (m) limit (%) Limit (%) index (%) swell % g/cm3 1 TP1-1 1.5 58 34 24 50 35 1.39 2 TP1-2 3 48 33 15 40 36 1.37 3 TP2-1 1.5 67 33 34 35 36 1.35 4 TP2-2 3 63 35 28 35 31 1.41 5 TP3-1 1.5 68 28 40 30 28 1.42 6 TP3-2 3 56 35 21 40 34 1.36 7 TP4-1 1.5 66 28 36 30 28 1.4 8 TP4-2 3 58 35 25 45 32 1.36 9 TP5-1 1.5 62 30 34 40 34 1.37 10 TP5-2 3 63 33 36 30 34 1.39 11 TP6-1 1.5 49 28 31 45 29 1.38 12 TP6-2 3 45 27 25 40 30 1.42 13 TP7-1 1.5 61 18 33 40 32 1.37 14 TP7-2 3 64 20 36 45 28 1.39 15 TP8-1 1.5 68 28 32 40 35 1.38 16 TP8-2 3 63 28 27 30 33 1.41 17 TP9-1 1.5 83 36 48 18 TP9-2 3 81 36 43

Serial Designation Depth(m) Liquid Plastic Percent Group Usual types General No limit index Passing on classification of significant rating as (%) (%) sieve #200 constitute sub- materials grade materials 1 TP1-1 1.5 58 24 98.8 A-7-5 Clayey soils Poor 2 TP1-2 3 48 15 >95 A-7-5 Clayey soils Poor 3 TP2-1 1.5 67 34 >95 A-7-5 Clayey soils Poor 4 TP2-2 3 63 28 >95 A-7-5 Clayey soils Poor 5 TP3-1 1.5 68 40 >95 A-7-6 Clayey soils Poor 6 TP3-2 3 56 21 >95 A-7-6 Clayey soils Poor 7 TP4-1 1.5 66 38 >95 A-7-6 Clayey soils Poor 8 TP4-2 3 58 23 >95 A-7-5 Clayey soils Poor 9 TP5-1 1.5 62 32 >95 A-7-6 Clayey soils Poor 10 TP5-2 3 63 30 >95 A-7-6 Clayey soils Poor 11 TP6-1 1.5 49 21 >95 A-7-6 Clayeysoils Poor 12 TP6-2 3 45 18 >95 A-7-6 Clayey soils Poor 13 TP7-1 1.5 61 43 >95 A-7-6 Clayey soils Poor 14 TP7-2 3 64 44 >95 A-7-6 Clayey soils Poor 15 TP8-1 1.5 68 40 >95 A-7-5 Clayey soils Poor 16 TP8-2 3 63 35 >95 A-7-5 Clayey soils Poor 17 TP9-1 1.5 83 47 >95 A-7-5 Clayey soils Poor 18 TP9-2 3 81 45 >95 A-7-5 Clayeysoils Poor Table: Classifications of soils based on AASHTO Classification system

Table:Classifications of soils based on USC Classification system

Serial Designation Depth(m) Liquid Plastic Percet Classification No limit index Passingon According to (%) (%) sieve #200 USCS 1 TP1-1 1.5 58 24 98.8 MH 2 TP1-2 3 48 15 >95 ML 3 TP2-1 1.5 67 34 >95 CH 4 TP2-2 3 63 28 >95 MH 5 TP3-1 1.5 68 40 >95 MH 6 TP3-2 3 56 21 >95 CH 7 TP4-1 1.5 66 38 >95 MH 8 TP4-2 3 58 23 >95 CH 9 TP5-1 1.5 62 32 >95 CH 10 TP5-2 3 63 30 >95 CH 11 TP6-1 1.5 49 21 >95 CL 12 TP6-2 3 45 18 >95 CL 13 TP7-1 1.5 61 43 >95 CH 14 TP7-2 3 64 44 >95 CH 15 TP8-1 1.5 68 40 >95 MH

16 TP8-2 3 63 35 >95 MH 17 TP9-1 1.5 83 47 >95 CH 18 TP9-2 3 81 45 >95 CH

Debremarkos LL PL Trial no 1 2 3 1 2 can no .g H2 B7 D4 15.8 15.9 mass of can.g 9.3 16 15.9 9.3 9.4 mass of can+wet soil .g 23.2 31.9 33.1 11.4 11.1 mass of can+dry soil .g 18.38 26.05 26.6 10.9 10.65 mass weter .g 4.82 5.85 6.5 0.5 0.45 mass of dry soil.g 9.08 10.05 10.7 1.6 1.25 water content% 53.08 58.21 60.75 31.25 36 number of blows 34 28 17 PL=33.6 Result LL=58 PI= LL-PL,24.4

LL PL Trial no 1 2 3 1 2 can no .g CA C6 C1 A2 A4 mass of can.g 9.5 9.4 16 9.6 9.5 mass of can+wet soil .g 23 22.1 30.1 12.4 11.9 mass of can+dry soil .g 18.3 17.98 24.5 11.7 11.3 mass weter .g 4.7 4.12 5.6 0.7 0.6 mass of dry soil.g 8.8 8.58 8.5 2.1 1.8 water content% 53.4 48 65.9 33.3 33.3 number of blows 23 25 17 result LL=48 PL=33.33 PI=14.7

Bahirdar test results

Table 4.Atterberg and Shrinkage Limit Test Result of the Study Area

Location Depth Liquid Plastic PI (%) Volumetric Specific Limit (%) Limit (%) Shrinkage gravity (%) Tikurit Mender 2.5 91.41 29.84 61.57 8.38 2.55

Zenzelma Abo 2 96.47 36.67 59.8 8.2 2.74 Gobame 2 99.51 33.53 65.98 13.95 2.64 Gordema 1.5 112.05 35.63 76.42 16.67 2.6 Gudadle 2 99.51 24.51 75 13.09 2.68 Gudadle 2.5 84.78 37.02 47.76 15.56 2.75 Baynes (Pit 1) 1 96.85 40.85 56 12.77 2.74 Kereza Mender 2 106.09 34.73 71.36 10.47 2.65 Chorka Mender 1.5 86.73 23.74 62.99 13.27 2.77 Sesa Beret (Pit 1) 2.5 88.11 21.41 66.7 13.78 2.72 Sesa Beret (Pit 2) 2 86.23 25.3 60.93 10.87 2.76 Lumame (Pit 1) 1 81.49 27.63 53.86 19.07 2.74 Lumame (Pit 2) 1.5 87.03 28.3 58.73 6.85 2.72 Mazoria 1.5 96.29 31.58 64.71 12.27 2.75 Sensela Bata 2.5 88.59 31.87 56.72 6.3 2.75 Kebele 16 1.5 93.93 34.4 59.53 12.86 2.6 Kebele 9 2 84.26 26.84 57.42 13.68 2.58 Kebele 7 (pit 1) 2.5 99.14 35.52 63.62 13.34 2.66 Kebele 10 1.5 93.49 37.16 56.33 16.4 2.68 Kebele 8 (pit 1) 2.5 90.66 32 58.66 11.74 2.63 Kebele 15 1 75 28.52 46.46 16.67 2.63 Kebele 13 1 82.19 32.18 50.01 10.63 2.74 Kebele 7 (pit 2) 1.5 78.5 28.27 50.23 15.18 2.64 Kebele 8 (pit 2) 2 89.39 44.84 44.55 15.18 2.67 Tp1-1 1.5 95.5 32.1 63.4 13.2 2.74 Tp2-1 1.5 82 28.3 53.7 17 2.72 Tp3-1 1.5 87.8 33 54.8 14.3 2.71 Tp4-1 2 81.3 27.6 53.7 15.2 2.78 Tp5-1 1.5 84.8 35.5 49.3 19.1 2.69 Tp6-1 1.5 90 29.1 60.9 16 2.81 Tp7-1 2 93.5 24.6 68.9 14.1 2.81 Tp8-1 2 93 31.4 61.6 17.7 2.8 Tp9-1 2 93.5 29.3 64.2 18.4 2.76 Tp10-1 2 82.8 31.7 51.1 14.8 2.77 Tp11-1 1.5 89.5 25.5 64 13.9 2.73 Tp12-1 1.5 80 25.4 54.6 17.9 2.72 Tp13-1 1.5 91 33.6 57.4 15

Location Depth Sand Silt Clay Free Dry Swelling Natural (%) (%) (%) swell density(γd) pressure moisture gm/cc (Kpa) content Tikurit Mender 2.5 6.92 16.08 77 120 1.28 547.52 26.51 Zenzelma Abo 2 4 23 73 110 1.39 344.5 31.2 Gobame 2 1.4 11.6 87 150 1.25 111.82 46.88 Gordema 1.5 3.77 10.23 86 170 1.29 514.61 28.11

Gudadle 2 2.4 12.6 85 160 1.22 175.38 40.1 Baynes (Pit 2) 2.5 1.21 12.79 82 100 1.36 165.6 40.39 Baynes (Pit 1) 1 7.5 19.5 73 110 1.18 377.27 41.15 Kereza Mender 2 0.61 21.39 78 215 1.05 79.95 61.24 ChorkaMender 1.5 3.15 16.85 80 120 1.39 379.24 28.14 SesaBeret(Pi 1) 2.5 4.48 13..52 82 80 1.28 538.33 31.1 SesaBeret(Pit2) 2 2.2 20.8 77 90 1.29 202.27 38.14 Lumame(Pit 1) 1 4.3 22.7 73 105 1.35 296.91 34.09 Lumame(Pit 2) 1.5 6.67 19.33 83.5 138 1.35 135.74 38.74 Mazoria 2 4.12 26.88 69 130 1.34 197.41 32.9 Sensela Bata 2.5 1.84 17.16 81 110 1.38 264.76 32.75 Kebele 16 1.5 2.26 17.74 80 200 1.29 114.37 40.99 Kebele 9 2 3.68 11.32 85 190 1.26 495.81 35.13 Kebele7 (pit 1) 2.5 184 21.16 77 120 1.24 186.8 41.96 Kebele 10 1.5 1.63 18.37 80 170 1.18 298.11 40.8 Kebele8 (pit 1) 2.5 3.17 16.83 80 200 1.38 210.22 37.19 Kebele 15 1 16.1 16.84 67 120 1.34 326.44 37.25 6 Kebele 13 1 4.57 14.63 81 130 1.17 140.64 48.61 Kebele7 (Pit 2) 1.5 16.1 17.85 66 150 1.04 92.12 59.45 5 Kebele8 (pit 2) 2 1.25 15.75 83 180 1.48 128.09 34.2 Tp1-1 1.5 21.9 20 58 78 Tp2-1 1.5 12.5 16.6 70.9 86 Tp3-1 1.5 17.1 18.5 64.4 98 Tp4-1 2 9.1 19.6 71.3 120 Tp5-1 1.5 9.3 20.4 70.3 10 Tp6-1 1.5 13.1 18.5 68.4 116 Tp7-1 2 10 26.3 63.7 113 Tp8-1 2 15 23 62 114 Tp9-1 2 25 19.6 55.4 125 Tp10-1 2 9.2 20.2 70.6 108 Tp11-1 1.5 10.6 22.1 67.3 124 Tp12-1 1.5 15.4 23.1 61.5 114 Tp13-1 1.5 11.7 20.4 67.9 95

PI (%) Clay Activity PI (%) Clay Activity (%) (%) 61.57 77 0.80 46.46 67 0.69 59.8 73 0.82 50.01 81 0.62 65.98 87 0.76 50.23 66 0.76 76.42 86 0.89 44.55 83 0.54 75 85 0.88 63.4 58 1.09

47.76 82 0.58 53.7 70.9 0.76 56 73 0.77 54.8 64.4 0.85 71.36 78 0.91 53.7 71.3 0.75 62.99 80 0.79 49.3 70.3 0.70 66.7 82 0.81 60.9 68.4 0.89 60.93 77 0.79 68.9 63.7 1.08 53.86 73 0.74 61.6 62 0.99 58.73 83.5 0.70 64.2 55.4 1.16 64.71 69 0.94 51.1 70.6 0.72 56.72 81 0.70 64 67.3 0.95 59.53 80 0.74 54.6 61.5 0.89 57.42 85 0.68 57.4 67.9 0.85 63.62 77 0.83 56.33 80 0.70 58.66 80 0.73

Merawi test results

Table: ,Atterberg Limit, Water content, liquidity index and consistency index of the soil

Serial Designation Depth(m) Liquid Plastic Plastic Natural Liqui Consisten No limit(%) Limit index(%) moisture dity cy (%) content Index Index(CI) (LI) 1 TP1-1 1.5 59.5 27.1 32.3 36.2 28.2 72.1 2 TP1-2 3 67.8 28.4 39.4 37.9 23.9 75.9 3 TP2-1 1.5 52.3 24.5 27.8 38.4 50 50 4 TP2-2 3 55.8 27 28.8 37.4 36.1 63.9 5 TP3-1 1.5 60.8 30.8 30.0 32.7 6.3 93.7 6 TP3-2 3 63.8 31.3 32.5 37.2 18.2 81.8 7 TP4-1 1.5 53.5 23.6 29.9 37.3 45.8 54.2 8 TP4-2 3 55.8 26 29.8 37.4 38.3 61.7 9 TP5-1 1.5 59.8 30.1 29.7 34.5 14.8 85.2 10 TP5-2 3 65.5 33.4 32.1 37.6 16.1 83.9 11 TP6-1 1.5 61.3 30.7 30.6 35.6 12.2 87.4 12 TP6-2 3 65.5 29.3 36.2 37.3 32.2 66.8

Table: Particle size analysis, density, Free swell, specific gravity

Serial Design Depth Gravel Silt Sand Clay Free Specifi Dry Bulk No ation (m) (%) (%) (%) (%) swell c gavity density density

kN/m3 kN/m3 1 TP1-1 1.5 0.3 19.15 5.55 75.00 16.7 2.73 11.9 16.2 2 TP1-2 3 0.2 17.40 0.50 81.91 18.3 2.75 11.6 16 3 TP2-1 1.5 0.04 16.03 10.54 73.40 15 2.7 12.3 17.1 4 TP2-2 3 0.02 16.40 6.80 76.77 16.7 2.74 12.3 16.9 5 TP3-1 1.5 0.02 27.43 1.23 71.32 14.5 2.72 11.3 15 6 TP3-2 3 0.08 26.54 1.00 72.35 15 2.72 12.2 16.7 7 TP4-1 1.5 0.16 31.98 2.62 65.24 18.3 2.73 12.7 17.4 8 TP4-2 3 0.12 35.07 1.22 63.59 19.4 2.74 12.9 17.7 9 TP5-1 1.5 0.16 16.00 0.98 82.86 18.3 2.72 12.6 17 10 TP5-2 3 0.16 7.85 0.73 91.26 20 2.76 13.3 18.3 11 TP6-1 1.5 0.04 18.89 1.32 79.74 15.3 2.71 12.6 17.1 12 TP6-2 3 0.06 13.43 1.69 84.82 17.9 2.72 12.5 17.1

Plastic index Clay Activity (%) (%) 32.3 75 0.431 39.4 81.91 0.481 27.8 73.4 0.379 28.8 76.77 0.375 30 71.32 0.421 32.5 72.35 0.449 29.9 65.24 0.458 29.8 63.59 0.469 29.7 82.86 0.358 32.1 91.26 0.352 30.6 79.74 0.384 36.2 84.82 0.427

Table: Unconfined compressive strength test result

Serial Design Depth Dry Natural PI(%) Specific undrained Unconfined Degree No ation (m) densit moistur gavity strength comprensiv of y e (Gs) (kN/m2) e saturatio (N/m3) content strength n (%) (kN/m2) S (%) 1 TP1-1 1.5 11.9 36.2 32.3 2.73 31.83 63.67 76.4 2 TP1-2 3 11.6 37.9 39.4 2.75 48.45 96.89 76 3 TP2-1 1.5 12.3 38.4 27.8 2.7 42.75 85.49 86.8 4 TP2-2 3 12.3 37.4 28.8 2.74 53.38 106.75 83.5

5 TP3-1 1.5 11.3 32.7 30.0 2.72 32.14 64.29 63.2 6 TP3-2 3 12.2 37.2 32.5 2.72 43.78 87.56 82.3 7 TP4-1 1.5 12.7 37.3 29.9 2.73 44.62 89.25 88.6 8 TP4-2 3 12.9 37.4 29.8 2.74 54.41 108.83 91.2 9 TP5-1 1.5 12.6 34.5 29.7 2.72 40.62 81.25 81 10 TP5-2 3 13.3 37.6 32.1 2.76 58 115.99 96.5 11 TP6-1 1.5 12.6 35.6 30.6 2.71 33.77 67.54 83.8 12 TP6-2 3 12.5 37.3 36.2 2.72 58.91 117.81 86.3

DebreBrhan soil test result

Table: Soil Classification based on USCS

Sr.NO Test Depth Percent amount of particle size LL PI Activity soil pit Gravel sand Silt clay Classification USCS 1 TP-1 1.5 0.35 2.84 29.21 67.5 73 40 0.59 CH 3 0 2.37 47.92 49.71 80 46 0.93 CH 2 TP-2 1.5 4.04 23.44 48.74 23.78 47 17 ML 3 1.68 34.11 55.44 8.77 43 11 ML 3 TP-3 1.5 0.11 14.03 42.41 43.45 66 38 0.87 CH 3 17.88 38.74 27.81 15.57 32 15 SC 4 TP-4 1.5 2.42 15.39 47.08 35.11 56 25 MH 3 0.43 33.23 48.53 17.81 44 15 ML 5 TP-5 1.5 1.31 7.91 41.72 49.06 77 43 0.88 CH 3 0.11 8.74 47.04 44.11 64 30 MH 6 TP-6 1.5 0.17 4.84 46.53 48.46 73 30 MH 3 1.45 7.39 47.23 43.93 60 32 0.73 CH 7 TP-7 1.5 0.03 7.26 36.24 56.47 70 38 0.67 CH 3 2.11 28.36 55.9 13.63 56 17 MH 8 TP-8 1.5 0.01 2.44 45.15 52.4 72 40 0.76 CH 3 0.05 17.27 35.08 47.6 48 26 0.55 CL 9 TP-9 1.5 1.46 20.7 43.07 34.77 47 22 0.63 CL 3 1.91 34.07 30 34.02 45 25 0.73 CL 10 TP- 1.5 0 6.86 42.91 50.23 62 33 0.66 CH 10 3 24.63 37.02 27.28 11.07 41 11 SM 11 TP- 1.5 0 15.4 39.55 45.05 58 29 0.64 CH 11 3 0.82 36.32 32.7 30.15 41 22 0.73 CL

Sr. Test Depth Particle size (%) LL PL PI AASHTO Type of General NO pit No.10 No.40 No.200 Classification material rating as

subgrade 1 TP- 1.5 0.35 2.84 29.21 73 33 40 A-7-5 Clay poor 1 soils 3 0 2.37 47.92 80 34 46 A-7-6 Clay poor soils 2 TP- 1.5 4.04 23.44 48.74 47 30 17 A-7-5 Clay poor 2 soils 3 1.68 34.11 55.44 43 32 11 A-7-6 Clay poor soils 3 TP- 1.5 0.11 14.03 42.41 66 28 38 A-7-6 Clay poor 3 soils 3 17.88 38.74 27.81 32 17 15 A-6 Clay poor soils 4 TP- 1.5 2.42 15.39 47.08 56 31 25 A-7-5 Clay poor 4 soils 3 0.43 33.23 48.53 44 29 15 A-7-5 Clay poor soils 5 TP- 1.5 1.31 7.91 41.72 77 34 43 A-7-5 Clay poor 5 soils 3 0.11 8.74 47.04 64 34 30 A-7-5 Clay poor soils 6 TP- 1.5 0.17 4.84 46.53 73 43 30 A-7-5 Clay poor 6 soils 3 1.45 7.39 47.23 60 28 32 A-7-6 Clay poor soils 7 TP- 1.5 0.03 7.26 36.24 70 32 38 A-7-6 Clay poor 7 soils 3 2.11 28.36 55.9 56 39 17 A-7-5 Clay poor soils 8 TP- 1.5 0.01 2.44 45.15 72 32 40 A-7-5 Clay poor 8 soils 3 0.05 17.27 35.08 48 22 26 A-7-6 Clay poor soils 9 TP- 1.5 1.46 20.7 43.07 47 25 22 A-7-6 Clay poor 9 soils 3 1.91 34.07 30 45 20 25 A-7-6 Clay poor soils 10 TP- 1.5 0 6.86 42.91 62 29 33 A-7-6 Clay poor 10 soils 3 24.63 37.02 27.28 41 30 11 A-7-5 Clay poor soils 11 TP- 1.5 0 15.4 39.55 58 29 29 A-7-5 Clay poor 11 soils 3 0.82 36.32 32.7 41 19 22 A-7-6 Clay poor soils

Table .General Relationship of consistency and Unconfined Compression strength of clays [9]

Consistency qu, KN/m2 Very soft 0-25 Soft 25-50 Medium 50-100 Stiff 100-200 Very Stiff 200-400 Hard >400

Sr.NO Test pit Depth Free swell

1.5 80

1 TP-1 3 100

1.5 50

2 TP-2 3 55

1.5 70

3 TP-3 3 60

1.5 50

4 TP-4 3 50

1.5 95

5 TP-5 3 85

1.5 90

6 TP-6 3 85

1.5 80

7 TP-7 3 50

8 TP-8 1.5 85

3 70

1.5 45

9 TP-9 3 35

1.5 95

10 TP-10 3 50

1.5 75

11 TP-11 3 50

From the test result the free swell falls in the range of 35 to 100. This shows most of the soil of DebreBirhan town is marginal in swelling potential property.

Sr No Test pit name UCS, qu Cohesion, C(kPa) Consistency 1 TP1-1.50m 176 88 Stiff 2 TP1-3.0m 83 41.5 Medium 3 TP3-3.0m 75 37.5 Medium 4 TP4-1.50m 134 67 Stiff 5 TP4-3.0m 203 101.5 Very Stiff 6 TP5-1.50m 233 116.5 Very Stiff 7 TP5-3.0m 120 60 Stiff 8 TP6-1.50m 114 57 Stiff 9 TP7-3.0m 194 97 Stiff 10 TP11-1.50m 141 70.5 Stiff 11 TP11-3.0m 186 93 Stiff It is observed that the consistency of DebreBirhan soil is either stiff or very stiff(strong)

Dessie soil data

Serial Designation Depth Liquid Plastic Plastic Free Gs Sand Silt Clay No (m) limit limit index swell (%) (%) (%) (%) (%) (%) (%) 1 TP1-1 1.5 88 50 38 130 2.83 2.6 26.69 70.71 2 TP1-2 3 73 51 22 60 2.65 2.7 46 51.3 3 TP2-1 1.5 86 59 27 100 2.76 3.1 34.23 62.67 4 TP2-2 3 72 44 28 110 2.81 4.65 30.23 65.12 5 TP3-1 1.5 64 40 24 70 2.68 7.85 35.45 56.7 6 TP3-2 3 71 42 29 80 2.71 13.25 28.05 58.7 7 TP4-1 1.5 69 41 28 85 2.74 12.25 23.65 64.1 8 TP4-2 3 61 38 23 65 2.67 9.75 37.35 52.9

9 TP5-1 1.5 71 39 32 90 2.82 2.1 31.59 66.31 10 TP5-2 3 68 45 23 69 2.69 1.95 44.29 53.76 11 TP6-1 1.5 62 50 22 65 2.66 10.35 39.1 50.55 12 TP6-2 3 72 41 31 90 2.78 16.55 18.25 65.2

Plastic Clay (%) index (%) Activity

38 70.71 0.53741

22 51.3 0.42885

27 62.67 0.43083

28 65.12 0.42998

24 56.7 0.42328

29 58.7 0.49404

28 64.1 0.43682

23 52.9 0.43478

32 66.31 0.48258

23 53.76 0.42783

22 50.55 0.43521

31 65.2 0.47546

Table Undrained shear strength of the tested soils

S/N Designation Depth(m) moisture UCS(kPa),qu cu(kPa) LI Consistency content 1 TP-1 3 31.7 623 311 -0.88 Hard 2 TP-2 3 32 521 261 -0.43 Hard 3 TP-3 3 29.3 513 256 -0.44 Hard 4 TP-4 3 24.2 586 293 -0.6 Hard 5 TP-5 3 26.9 604 302 -0.79 Hard 6 TP-6 3 31.5 432 216 -0.31 Hard

The negative values of the liquidity index indicate water content smaller than the Liquid limit, and the state of soils was hard.

Relationship between UCS and consistency of clays is greater than 400 KN/m2is hard [9]

Table. Classification of the tested soils according to AAHTO and USCS

Seria Designatio Depth Liquid Plastic Gs Soil Soil l No n (m) limit(% index(% classification classification ) ) USCS , AASHTO 1 TP1-1 1.5 88 38 2.8 MH A-7-5 3 2 TP1-2 3 73 22 2.6 MH A-7-5 5 3 TP2-1 1.5 86 27 2.7 MH A-7-5 6 4 TP2-2 3 72 28 2.8 MH A-7-5 1 5 TP3-1 1.5 64 24 2.6 MH A-7-5 8 6 TP3-2 3 71 29 2.7 MH A-7-5 1 7 TP4-1 1.5 69 28 2.7 MH A-7-5 4 8 TP4-2 3 61 23 2.6 MH A-7-5 7 9 TP5-1 1.5 71 32 2.8 MH A-7-5 2 10 TP5-2 3 68 23 2.6 MH A-7-5 9 11 TP6-1 1.5 62 22 2.6 MH A-7-5 6 12 TP6-2 3 72 31 2.7 MH A-7-5 8

Gondar soil data

Engineering properties Index property Test Results Clay (%) 41.6 – 82.3% Silt (%) 16.45 -56.53% Liquid limit (%) 68.89 -110.2% Plastic limit (%) 18.5 -33.9% Plastic index (%) 45.8 -78.6%

Free swell (%) 82 -107.5%

Specific gravity 2.6 -2.83 Moisture content (%) 15.87 -52.3% Unconfined 94.12 -276 compression strength (kPa)

Clay PI Activity (%) 41.6 45.8 1.10 82.3 78.6 0.96

Kemise soil data

Test pit Depth LL PL PI Moisture (m) content TP-1 1.5 53.8 26.2 27.6 27.03 3 64.5 32.5 32 32.74 TP-2 1.5 53.3 30.4 22.9 21.74 3 51.1 33.1 18 22.45 TP-3 1.5 36.8 24.7 12.1 14.01 3 45.3 25.2 20.1 17.15 TP-4 1.5 61.2 32.4 28.8 23.75 3 45.1 27.5 17.6 31.99 TP-5 1.5 58.9 31.2 27.7 27.58 3 67.5 33.3 34.2 34.85 TP-6 1.5 65.8 31.1 34.7 37.21 TP-7 1.5 59.5 29.2 30.3 38.4 TP-8 1.5 65.2 31.8 33.4 35.77 TP-9 1.5 37.4 27.4 10 12.9 3 30.7 24.2 6.5 17.23 TP-10 1.5 81.4 33 48.4 27.6 3 84.9 29.5 55.4 36.67 TP-11 1.5 52.7 30.9 21.8 23.17 3 40 23.3 16.7 24.85

PI Clay(%) Activity 27.6 36.78 0.75 32 39 0.821 22.9 36.54 0.627 18 33.52 0.537 12.1 25.91 0.467 20.1 30.91 0.65 28.8 36.11 0.798 17.6 21.78 0.808 27.7 32.51 0.852 34.2 45.17 0.757 34.7 40.13 0.865 30.3 35.36 0.857 33.4 46.4 0.72 10 16.6 0.602 6.5 11.07 0.587 48.4 53.39 0.907 55.4 57.16 0.969 21.8 30.98 0.704 16.7 50.12 0.333

Table: Skempton activity number, free swell, specific gravity of investigated soils

Test pit Depth PI Percent of Activity Free swell specific (m) clay gravity TP-1 1.5 27.6 36.78 0.75 55 2.63 3 32 39 0.82 57.5 2.64 TP-2 1.5 22.9 36.54 0.63 40 2.63 3 18 33.52 0.54 35 2.67 TP-3 1.5 12.1 25.91 0.47 35 2.72 3 20.1 30.91 0.65 25 2.7 TP-4 1.5 28.8 36.11 0.80 35 2.69 3 17.6 21.78 0.81 27.5 2.64 TP-5 1.5 27.7 32.51 0.85 40 2.69 3 34.2 45.17 0.76 45 2.7 TP-6 1.5 34.7 40.13 0.86 60 2.67 TP-7 1.5 30.3 35.36 0.86 85 2.74 TP-8 1.5 33.4 46.4 0.72 60 2.68 TP-9 1.5 10 16.6 0.60 15 2.7 3 6.5 11.07 0.59 20 2.71

TP-10 1.5 48.4 53.39 0.91 95 2.73 3 55.4 57.16 0.97 97.5 2.7 TP-11 1.5 21.8 30.98 0.70 30 2.67 3 16.7 50.12 0.33 75 2.6

Table: Summary of the combined grain size analysis result

Test pit Depth(m) PI Percent amount of particle size Clay gravel sand Silt TP-1 1.5 27.6 36.78 0.11 8.138 54.93 3 32 39 0.10 1.4 59.5 TP-2 1.5 22.9 36.54 0.31 3.16 59.99 3 18 33.52 0.54 10.77 55.17 TP-3 1.5 12.1 25.91 1.43 22.78 49.88 3 20.1 30.91 2.40 11.16 55.33 TP-4 1.5 28.8 36.11 _ 2.14 61.75 3 17.6 21.78 11.87 27.02 39.33 TP-5 1.5 27.7 32.51 0.07 5.44 61.98 3 34.2 45.17 _ 2.06 52.77 TP-6 1.5 34.7 40.13 _ 3.11 56.76 TP-7 1.5 30.3 35.36 0.26 5.82 58.56 TP-8 1.5 33.4 46.4 0.95 3.94 48.71 TP-9 1.5 10 16.6 _ 43.22 40.18 3 6.5 11.07 0.44 54.42 34.07 TP-10 1.5 48.4 53.39 1.32 3.15 42.14 3 55.4 57.16 0.32 1.4 41.12 TP-11 1.5 21.8 30.98 _ 3.06 65.96 3 16.7 50.12 0.06 6.71 43.11

Table: Classifications of soils based on USCS Classification system [3]

Test pit Depth PI Percent amount of particle size LL PI USC (m) Clay Gravel sand Silt S TP-1 1.5 27.6 36.78 0.11 8.138 54.93 53. 27. CH 8 6 3 32 39 0.10 1.4 59.5 64. 32 MH 5 TP-2 1.5 22.9 36.54 0.31 3.16 59.99 53. 22. MH 3 9

3 18 33.52 0.54 10.77 55.17 51. 18 MH 1 TP-3 1.5 12.1 25.91 1.43 22.78 49.88 36. 12. ML 8 1 3 20.1 30.91 2.40 11.16 55.33 45. 20. CL 3 1 TP-4 1.5 28.8 36.11 _ 2.14 61.75 61. 28. MH 2 8 3 17.6 21.78 11.87 27.02 39.33 45. 17. ML 1 6 TP-5 1.5 27.7 32.51 0.07 5.44 61.98 58. 27. MH 9 7 3 34.2 45.17 _ 2.06 52.77 67. 34. MH 5 2 TP-6 1.5 34.7 40.13 _ 3.11 56.76 65. 34. MH 8 7 TP-7 1.5 30.3 35.36 0.26 5.82 58.56 59. 30. MH 5 3 TP-8 1.5 33.4 46.4 0.95 3.94 48.71 65. 33. MH 2 4 TP-9 1.5 10 16.6 _ 43.22 40.18 37. 10 SM 4 3 6.5 11.07 0.44 54.42 34.07 30. 6.5 SM 7 TP-10 1.5 48.4 53.39 1.32 3.15 42.14 81. 48. CH 4 4 3 55.4 57.16 0.32 1.4 41.12 84. 55. CH 9 4 TP-11 1.5 21.8 30.98 _ 3.06 65.96 52. 21. MH 7 8 3 16.7 50.12 0.06 6.71 43.11 40 16. CL 7 Table: Classifications of soils based on AASHTO Classification system [1]

Test Depth PI percent passing sieve LL PI Group significant General pit (m) No.10 No.40 No.200 Classification constituent rating as material sub grade material TP-1 1.5 27.6 99.83 98.94 91.7 53.8 27.6 A-7-6 Clayey Poor Soils 3 32 99.78 99.41 98.5 64.5 32 A-7-5 Clayey Poor Soils TP-2 1.5 22.9 99.33 98.47 96.53 53.3 22.9 A-7-5 Clayey Poor Soils 3 18 98.56 96.04 88.69 51.1 18 A-7-5 Clayey Poor Soils

TP-3 1.5 12.1 96.67 90.16 75.79 36.8 12.1 A-6 Clayey Poor Soils 3 20.1 95.3 92.60 86.44 45.3 20.1 A-7-6 Clayey Poor Soils TP-4 1.5 28.8 99.96 99.64 97.86 61.2 28.8 A-7-5 Clayey Poor Soils 3 17.6 79.35 69.87 61.11 45.1 17.6 A-7-6 Clayey Poor Soils TP-5 1.5 27.7 99.64 98.58 94.49 58.9 27.7 A-7-5 Clayey Poor Soils 3 34.2 99.8 99.08 97.94 67.5 34.2 A-7-5 Clayey Poor Soils TP-6 1.5 34.7 99.95 99.47 96,89 65.8 34.7 A-7-6 Clayey Poor Soils TP-7 1.5 30.3 98.57 96.29 93.92 59.5 30.3 A-7-6 Clayey Poor Soils TP-8 1.5 33.4 98.37 96.99 95.11 65.2 33.4 A-7-5 Clayey Poor Soils TP-9 1.5 10 99.68 94.43 56.78 37.4 10 A-4 Clayey Poor Soils 3 6.5 99.25 89.07 45.14 30.7 6.5 A-4 Clayey Poor Soils TP- 1.5 48.4 97.86 97.05 95.53 81.4 48.4 A-7-5 Clayey Poor 10 Soils 3 55.4 99.24 98.67 98.28 84.9 55.4 A-7-5 Clayey Poor Soils TP- 1.5 21.8 99.96 99.76 96.94 52.7 21.8 A-7-5 Clayey Poor 11 Soils 3 16.7 99.87 98.78 93.23 40 16.7 A-6 Clayey Poor Soils

Test Depth LL PL PI Moisture UCS LI Consistency pit (m) content TP-1 1.5 53.8 26.2 27.6 27.03 57 0.03 Medium 3 64.5 32.5 32 32.74 127 0.01 Stiff TP-2 1.5 53.3 30.4 22.9 21.74 130 -0.38 Stiff 3 51.1 33.1 18 22.45 166 -0.59 Stiff TP-4 1.5 61.2 32.4 28.8 23.75 247 -0.3 Very stiff 3 45.1 27.5 17.6 31.99 195 0.26 Stiff TP-9 1.5 37.4 27.4 10 12.9 36 -1.45 Soft 3 30.7 24.2 6.5 17.23 30 -1.07 Soft TP-10 1.5 81.4 33 48.4 27.6 186 -0.11 Stiff 3 84.9 29.5 55.4 36.67 85 0.13 Medium

According to soil classification on plasticity index values stated in [4], the soil samples investigated under this thesis found within low to high plasticity.

Woldiya soil test results

No Test depth(m LL PL PI moisture GS Free pit ) content swell 1 TP-1 1.5 96.63 30.08 66.55 31.72 2.89 128 3 90.84 32.95 57.89 2.76 120 2 TP-2 3 72.77 32.54 40.23 29.45 2.79 88 3 TP-3 0.9 39.97 30.64 9.33 2.65 45 3 34.11 28.62 5.49 2.67 39 4 TP-4 1.5 81.79 33.78 48.01 31.08 2.75 100 3 73.02 31.27 41.75 2.78 72 5 TP-5 3 74.06 30.97 43.09 28.5 2.8 85

AASHTO Classification System

Gravel 75mm - 4.75mm

Sand 4.75mm - 0.075mm

Silt 0.075mm - 0.002mm

Clay < 0.002mm

No Test depth LL PL PI Percent amount of particle AASHTO Usual USCS pit (m) size Classification types of Gravel Sand silt clay significant constituent material 1 TP-1 1.5 96.63 30.08 66.55 4.3 4.85 41.6 49.25 A-7-5 Clayey CH soils 3 90.84 32.95 57.89 5.43 2.78 45.46 46.33 A-7-5 Clayey CH soils 2 TP-2 3 72.77 32.54 40.23 1.3 2.42 62.98 33.3 A-7-5 Clayey CH soils 3 TP-3 0.9 39.97 30.64 9.33 15.9 17.52 56.38 10.2 A-4 Silt soils ML 3 34.11 28.62 5.49 15.89 18.65 59.3 6.16 A-4 Silt soils ML 4 TP-4 1.5 81.79 33.78 48.01 1.75 2.22 50.46 45.57 A-7-5 Clayey CH soils 3 73.02 31.27 41.75 2.8 2.63 55.88 38.69 A-7-5 Clayey CH soils 5 TP-5 3 74.06 30.97 43.09 2.75 6.37 51.02 39.86 A-7-5 Clayey CH soils

No Test Dept LL PL PI Percent amount of particle size Activit pit h Gravel Sand silt clay y (m) 1 TP-1 1.5 96.63 30.08 66.5 4.3 4.85 41.6 49.25 1.35 5 3 90.84 32.95 57.8 5.43 2.78 45.46 46.33 1.25 9 2 TP-2 3 72.77 32.54 40.2 1.3 2.42 62.98 33.3 1.21 3 3 TP-3 0.9 39.97 30.64 9.33 15.9 17.52 56.38 10.2 0.91 3 34.11 28.62 5.49 15.89 18.65 59.3 6.16 0.89 4 TP-4 1.5 81.79 33.78 48.0 1.75 2.22 50.46 45.57 1.05 1 3 73.02 31.27 41.7 2.8 2.63 55.88 38.69 1.08 5 5 TP-5 3 74.06 30.97 43.0 2.75 6.37 51.02 39.86 1.08 9

From the above table , the soil in test pit one is active and the remaining falls in normal range. This implies that soil collected from test pit one has high swelling potential.

Debre tabor soil test result

NO. Sample location Depth(m) LL PL PI Free Gs swell 1 Agbar 1.5 88 27.36 60.64 110 2.55 3 82 32.84 49.16 125 2.62 2 Zufill 1.5 82 31.17 50.83 90 2.7 2.6 74 28.65 45.35 85 2.65 3 Weybla 1.5 86 31.21 54.79 140 2.64 2.8 82 27.61 54.39 115 2.59 4 Aringo 1.5 75 26.74 48.26 120 2.54 3 78 28.27 49.73 130 2.58 5 Kegaweha 1.5 67 24.43 42.57 70 2.82 2.4 81 29.26 51.74 100 2.69 6 Maremiyabet 1.5 79 29.51 49.49 95 2.79 7 Stadium 1.5 82 29.86 52.14 135 2.62 8 high school 1.5 85 31.33 53.67 110 2.67 2.7 96 35.56 60.44 120 2.63 9 Aringo road 1 1.5 78 34.19 43.81 115 2.53

Aringo road 2 2.4 74 28.08 45.92 105 2.5 10 Zufill 1 1 78 24.58 53.42 125 2.54 Zufill2 1 92 37.59 54.41 130 2.65 11 Ayermarefia 1 97 33.91 63.09 145 2.62 1.3 89 35.35 53.65 140 2.51 12 Hagereselam 1 87 30.64 56.36 120 2.7 13 Gafat elementary 1 81 30.86 50.14 105 2.55 school

NO Sample Depth Natural moisture Dry density PI swelling . location (m) content(%) gm/cc pressure (kPa) 1 Agbar 1.5 31.62 1.28 30.34 420 3 25.6 1.31 24.29 490 2 Zufill 1.5 37.99 1.23 36.76 420 2.6 58.63 1.03 57.6 80 3 Weybla 1.5 34.65 1.24 33.41 390 2.8 24.94 1.33 23.61 440 4 Aringo 1.5 36.44 1.21 35.23 320 3 52.51 1.13 51.38 270 5 Kegaweha 1.5 37.04 1.31 35.73 180 2.4 52.39 1.19 51.2 150 6 Maremiyabet 1.5 29.82 1.39 28.43 290 7 Stadium 1.5 48.43 1.19 47.24 275 8 high school 1.5 36.71 1.34 35.37 280 2.7 58.8 1.1 57.7 120 9 Aringo road 1 1.5 46.15 1.21 44.94 175 Aringo road 2 2.4 49.08 1.2 47.88 160 10 Zufill 1 1 51.25 1.15 50.1 310 Zufill2 1 48.09 1.18 46.91 360 11 Ayermarefia 1 46.09 1.23 44.86 260 1.3 43.03 1.24 41.79 360 12 Hagereselam 1 29.27 1.33 27.94 240 13 Gafat 1 31.83 1.28 30.55 250 elementary school Wereta soil test result

Test pit Depth LL (%) PL (%) PI (%) Wn (%) Gs FS (m)

TP-1 1.5 115 33 82 39.4 2.68 90 3 116 42 74 42.3 2.71 82.5 TP-2 1.5 127 44 83 27.9 2.64 101 3 106 43 63 36.8 2.7 74 TP-3 1.5 124 39 85 28.1 2.68 75 3 98 28 70 36.6 2.72 97.5 TP-4 1.5 67 42 25 17 2.81 _ 3 60 55 5 19 2.81 TP-5 1.5 111 40 71 30.4 2.63 100 3 91 35 56 33.5 2.69 83 TP-6 1.5 93 36 57 33.4 2.73 80 3 87 33 54 38.1 2.81 76 TP-7 1.5 67 51 16 38.3 2.79 45.5 3 67 62 5 26.5 2.79 TP-8 1.5 93 75 18 56.4 2.81 45 3 91 75 16 59.2 2.84 TP-9 1.5 100 32 68 32.5 2.73 85 3 95 30 65 34.8 2.81 91.5 TP-10 1.5 80 58 22 26.5 2.81 3 72 56 16 29.1 2.81

Test pit Depth Percentage amount of particle size (m)

Gravel Sand Silt Clay (%) (%) (%) (%) TP-1 1.5 0 6.1 15.6 78.3 3 0 1.5 26.26 72.24 TP-2 1.5 0.63 5.93 11.98 81.46 3 0.06 3.34 21.18 75.42 TP-3 1.5 0.12 2.77 13.37 83.74 3 0 1.74 21.46 76.8 TP-4 1.5 27.62 10.74 13.97 29.67 3 52.51 32.02 8.99 6.48 TP-5 1.5 1.07 2.54 21.34 75.05 3 5.32 7.44 19.09 68.15 TP-6 1.5 1.27 4.42 21.52 72.79 3 0 0.82 27.16 72.02 TP-7 1.5 0.55 5.1 21.99 72.36 3 9.21 62.68 16.3 11.81

TP-8 1.5 1.41 8.89 61.16 28.54 3 2.34 14.09 45.56 38.01 TP-9 1.5 1.33 6.62 19.7 72.35 3 0.02 1.4 26.62 71.96 TP-10 1.5 29.55 12.74 28.27 29.44 3 27.83 18.17 31.63 22.37

Test Depth Percentage amount of particle size LL PI Classification pit (m) %Gravel %Sandfraction %Silt %Clay according to fraction(75mm- (75mm- Fraction finer Fraction finer USCS 4.75mm) 4.75mm) than0.075mm than0.025mm TP- 1.5 0.0 7.0 22 72 115 82 CH 1 3 0.0 1.5 37 61.5 116 74 CH TP- 1.5 0.6 6.0 19.4 74 127 83 CH 2 3 0.1 3.3 28.1 68.5 106 63 MH TP- 1.5 0.1 2.8 23.1 74 124 85 CH 3 3 0.0 1.7 28.9 69.4 98 70 CH TP- 1.5 27.6 10.8 36.18 25.42 67 25 MH 4 3 52.5 32.1 10.4 5 60 5 GM TP- 1.5 1.1 2.5 29.4 67 111 71 CH 5 3 5.3 7.4 27.9 59.3 91 56 MH TP- 1.5 1.3 4.4 28.3 66 93 57 CH 6 3 0.0 0.8 34.2 65 87 54 CH TP- 1.5 0.6 5.1 26.9 67.5 67 16 MH 7 3 9.2 62.7 18.6 9.5 67 5 SM TP- 1.5 1.4 8.9 69.2 20.5 93 18 MH 8 3 2.3 14.1 58.1 25.5 91 16 MH TP- 1.5 1.3 6.7 27 65 100 68 CH 9 3 0.0 1.4 33.1 65.5 95 65 CH TP- 1.5 29.6 12.7 32.98 24.72 80 22 MH 10 3 27.8 18.2 37 17 72 16 MH

Test Dept Persentage passing by weight LL PI AASHTO pit h No10 No 40 No 200 Clasification (m) sieve sieve sieve TP-1 1.5 98.56 95.8 94 115 82 A-7-5 3 99.9 99.8 98 116 74 A-7-5 TP-2 1.5 98.07 96.1 93 127 83 A-7-5 3 99.76 99 97 106 63 A-7-5

TP-3 1.5 99.62 98.6 97 124 85 A-7-5 3 99.92 99.6 98 98 70 A-7-5 TP-4 1.5 69.39 67 62 67 25 A-7-5 3 42.55 33.2 15 60 5 A-7-5 TP-5 1.5 98.48 97.4 96 111 71 A-7-5 3 90.96 88.3 87 91 56 A-7-5 TP-6 1.5 97.87 95.5 94 93 57 A-7-5 3 99.98 99.8 99 87 54 A-7-5 TP-7 1.5 98.91 97.8 94 67 16 A-7-5 3 84.7 70.9 28 67 5 A-2-5 TP-8 1.5 96.7 93.8 90 93 18 A-7-5 3 94.87 92 84 91 16 A-7-5 TP-9 1.5 97.28 93.9 92 100 68 A-7-5 3 99.9 99.6 99 95 65 A-7-5 TP- 1.5 66.91 63.9 58 80 22 A-7-5 10 3 69.2 64 54 72 16 A-7-5

Test pit Depth LL PL PI %Clay Fraction Activity UCS Su Consistency (m) (%) (%) (%) finer than0.025mm TP-1 1.5 115 33 82 72 1.14 184 92 Stiff 3 116 42 74 61.5 1.20 178 89 Stiff TP-2 1.5 127 44 83 74 1.12 274 137 Very stiff 3 106 43 63 68.5 0.92 245 122 Very stiff TP-3 1.5 124 39 85 74 1.15 251 125 Very stiff 3 98 28 70 69.4 1.01 253 127 Very stiff TP-4 1.5 67 42 25 25.42 0.98 Stone fragment 3 60 55 5 5 1.00 TP-5 1.5 111 40 71 67 1.06 254 123 Very stiff 3 91 35 56 59.3 0.94 231 116 Very stiff TP-6 1.5 93 36 57 66 0.86 235 117 Very stiff 3 87 33 54 65 0.83 211 105 Very stiff TP-7 1.5 67 51 16 67.5 0.24 Gravel and sand 3 67 62 5 9.5 0.53 TP-8 1.5 93 75 18 20.5 0.88 3 91 75 16 25.5 0.63 TP-9 1.5 100 32 68 65 1.05 242 120 Very stiff 3 95 30 65 65.5 0.99 239 121 Very stiff TP-10 1.5 80 58 22 24.72 0.89 _