DOCSLIB.ORG

Intro to Soil Mechanics: the What, Why &

Total Page：16

File Type：pdf, Size：1020Kb

Download full-text PDF Read full-text
Intro to Soil Mechanics: the What, Why & Intro to Soil Mechanics: the what, why & how José E. Andrade, Caltech Thursday, June 23, 2011 The What? Thursday, June 23, 2011 What is Soil Mechanics? erdbaumechanik The application of the laws of mechanics (physics) to soils as engineering materials Karl von Terzaghi is credited as the father of erdbaumechanik Thursday, June 23, 2011 sands & gravels clays & silts Thursday, June 23, 2011 The Why? Thursday, June 23, 2011 Sandcastles what holds them up? Thursday, June 23, 2011 Palacio de Bellas Artes Mexico, DF uniform settlement Thursday, June 23, 2011 The leaning tower of Pisa differential settlement Thursday, June 23, 2011 ! Teton dam dam failure Thursday, June 23, 2011 Niigata earthquake liquefaction Thursday, June 23, 2011 Katrina New Orleans levee failure Thursday, June 23, 2011 MER: Big Opportunity xTerramechanics Thursday, June 23, 2011 MER: Big Opportunity xTerramechanics Thursday, June 23, 2011 The How? Thursday, June 23, 2011 Topics in classic Soil Mechanics • Index & gradation • Soil classification • Compaction • Permeability, seepage, and effective stresses • Consolidation and rate of consolidation • Strength of soils: sands and clays Thursday, June 23, 2011 Index & gradation Definition: soil mass is a collection of particles and voids in between (voids can be filled w/ fluids or air) solid particle fluid (water) Each phase has volume and mass gas (air) Mechanical behavior governed by phase interaction Thursday, June 23, 2011 solid Index & gradation water+air=voids Key volumetric ratios Key mass ratio void ratio water content Vv Mw e = [0.4,1] sand w = <1 for most soils V M s [0.3,1.5] clays s >5 for marine, organic Key link mass & volume Vv porosity η = Vt [0,1] ρ = M/V moist, solid, water, dry, etc. Vw saturation S = Vv [0,1] ratios used in practice to characterize soils & properties Thursday, June 23, 2011 Gradation & classification Grain size is main classification feature sands & clays & gravels silts • can see grains • cannot see grains • mechanics~texture • mechanics~water • d>0.05 mm • d<0.05 mm Soils are currently classified using USCS (Casagrande) Thursday, June 23, 2011 Fabric in coarsely-grained soils “loose packing”, high e Vv relative e = “dense packing”, low e Vs emax greatest possible, loosest packing emin lowest possible, densest packing emax e ID = e e− relative density max− min strongly affects engineering behavior of soils Thursday, June 23, 2011 Typical problem(s)xb in Soil Mechanics • Compact sand fill • Calculate consolidation of clay • Calculate rate of consolidation • Determine strength of sand SAND FILL • Calculate F.S. on sand (failure?) • Need: stresses & matl behavior PISA CLAY ROCK (UNDERFORMABLE, IMPERMEABLE) Thursday, June 23, 2011 Modeling tools Thursday, June 23, 2011 Theoretical framework • continuum mechanics • constitutive theory js W W • computational inelasticity 0 x X • nonlinear finite elements jf f x2 W0 x1 Thursday, June 23, 2011 Theoretical framework • continuum mechanics • constitutive theory balance of mass • computational inelasticity p˙ φ + ∇·v = −∇ · q Kf • nonlinear finite elements ∇·σ + γ = 0 balance of momentum Thursday, June 23, 2011 Theoretical framework • continuum mechanics = h • constitutive theory q k ·∇ darcy ! ep σ˙ = c : "˙ hooke • computational inelasticity k permeability tensor • nonlinear finite elements controls fluid flow ep c mechanical stiffness controls deformation Thursday, June 23, 2011 Theoretical framework • continuum mechanics t3 • constitutive theory tr tn+1 Fn+1 tn+1 F • computational inelasticity n tn • nonlinear finite elements t1 t2 Thursday, June 23, 2011 Theoretical framework • continuum mechanics • constitutive theory • computational inelasticity • nonlinear finite elements Displacement node Pressure node Thursday, June 23, 2011 Finite Element Method (FEM) • Designed to approximately solve PDE’s • PDE’s model physical phenomena • Three types of PDE’s: ) & ) '(1 '(1 '(0 '(0 '(/ '(/ '(. '(. "!#$ '(- '(- ! • Parabolic: fluid flow % '(, '(, '(+ '(+ '(* '(* '() '() ' & ' ' '() '(* '(+ '(, '(- '(. '(/ '(0 '(1 ) !!"!#$ • Hyperbolic: wave eqn • Elliptic: elastostatics Thursday, June 23, 2011 FEM recipe Strong from Weak form Galerkin form Matrix form Thursday, June 23, 2011 Multi-D deformation with FEM ∇·σ + f = 0 in Ω equilibrium u = g on Γg e.g., clamp σ · n = h on Γh e.g., confinement Γg Constitutive relation: Ω given u get σ Γ h e.g., elasticity, plasticity Thursday, June 23, 2011 Modeling Ingredients 1. Set geometry 2.Discretize domaiin H 3. Set matl parameters 4.417 4. Set B.C.’s 5. Solve B Thursday, June 23, 2011 Modeling Ingredients 1. Set geometry 2. Discretize domain 3. Set matl parameters 4. Set B.C.’s 5. Solve Thursday, June 23, 2011 Modeling Ingredients 1. Set geometry 2. Discretize domain 3. Set matl parameters 4. Set B.C.’s 5. Solve Thursday, June 23, 2011 Modeling Ingredients !a 1. Set geometry 2. Discretize domain !r 3. Set matl parameters 4. Set B.C.’s 5. Solve Thursday, June 23, 2011 Modeling Ingredients !a 1. Set geometry 2. Discretize domain !r 3. Set matl parameters 4. Set B.C.’s 5. Solve Thursday, June 23, 2011 FEM Program TIME STEP LOOP ITERATION LOOP ASSEMBLE FORCE VECTOR AND STIFFNESS MATRIX ELEMENT LOOP: N=1, NUMEL GAUSS INTEGRATION LOOP: L=1, NINT constitutive CALL MATERIAL SUBROUTINE model CONTINUE CONTINUE CONTINUE T = T + !T Thursday, June 23, 2011 Material behavior: shear strength • Void ratio or relative density • Particle shape & size Engineers have developed models to account for most • Grain size distribution of these variables • Particle surface roughness • Water Elasto-plasticity framework of choice • Intermediate principal stress • Overconsolidation or pre-stress Thursday, June 23, 2011 A word on current characterization methods Direct Shear Triaxial Pros: cheap, simple, fast, Pros: control drainage & stress good for sands path, principal dir. cnst., Cons: drained, forced failure, more homogeneous non-homogeneous Cons: complex Thursday, June 23, 2011 Material models for sands should capture • Nonlinearity and irrecoverable deformations v • Pressure dependence A • Difference tensile and p compressive strength Dv C • Relative density dependence B • Nonassociative plastic flow log -p ’ Thursday, June 23, 2011 Material models for sands should capture • Nonlinearity and irrecoverable deformations s’ • Pressure dependence 200 vc 191 kPa 241 310 • Difference tensile and 380 compressive strength (kPa) 100 q • Relative density dependence 0 100 200 300 • Nonassociative plastic flow -p’ (kPa) Thursday, June 23, 2011 Material models for sands should capture • Nonlinearity and irrecoverable deformations t’3 Von Mises • Pressure dependence Mohr Coulomb • Difference tensile and compressive strength • Relative density dependence t’ t’ • Nonassociative plastic flow 1 2 Loose sand Dense sand Thursday, June 23, 2011 Material models for sands should capture • Nonlinearity and irrecoverable deformations 1000 (kPa) 800 | • Pressure dependence 600 sa ar 400 |s -s • Difference tensile and 200 s compressive strength r 0 0 2 4 6810 ea (%) • Relative density dependence 4 3 • Nonassociative plastic flow 2 Dense Sand 1 Loose Sand (%) 0 v e -1 Thursday, June 23, 2011 Material models for sands should capture • Nonlinearity and irrecoverable deformations Yield Function q Plastic Potential • Pressure dependence Flow vector • Difference tensile and compressive strength • Relative density dependence • Nonassociative plastic flow -p’ Thursday, June 23, 2011 Elasto-plasticity in one slide Hooke’s law σ˙ = cep : ˙ Additive decomposition of strain ˙ = ˙ e + ˙ p Convex elastic region F (σ, α)=0 Non-associative flow ˙ p = λ˙ g, g := ∂G/∂σ K-T optimality λ˙ F =0 λ˙ H = ∂F/∂α α˙ − · Elastoplastic constitutive tangent 1 cep = ce ce : g f : ce, χ = H g : ce : f − χ ⊗ − Thursday, June 23, 2011 Examples Thursday, June 23, 2011 Example of elasto-plastic model !3 "=1 q "=7/9 N=0 N=0.5 $ # i p' M ! ! 1 2 v CSL CSL (a) (b) v1 Figure 3: Th~ree invariant yield surface on (a) deviatorF ic=planeFat d(iffeσrentv,aluπes of) and (b) l i yi meridian plane at different values of N. vc y G = G(σ, π¯ ) v2 with i M [1 + ln (πi/p)] if N = 0 η = (2.4) ln-p’ N/(1 N) M/N 1 (1 N) (p/πHi) − = Hif N(>p0., πi, ψ) -p’ − − -pi The function ζ controls the cross-sectional shape of the yield function on a deviatoric plane Thursday, June 23, 2011 Figure 2: Geometricasrepra fuesenctionntationofof ththe stateLode’sparameangle.ter ψW. e adopt the shape function proposed by Gudehus and where the stored energy is an isotropiArgyc furisnction[18,of19]thebelasticecausstraie ofnitstensormatheme. Thateictotalal simplistresscity i.e., tensor σ is decomposed according to Terzaghi’s well known expression for fully saturated soils (1 + ) + (1 ) cos 3θ i.e., σ = σ pδ, where p is the pore fluid pressure and is negative underζcom(θ)pres= sion, following − (2.5) − 2 continuum mechanics convention. The tensor δ is the second-order identity. Let us define three independentwhereinvarianastsshoforwnthe ineffeFiguctiverestr3,essthetensorellipσticit, y constant controls the form of the cross-section going from perfectly circular 3= 1 to convex triangular for = 7/9. The shape function 1 2 1 tr s p = tr σ, q = s , cos 3θ = 3 (2.2) 3 with <31 reflects√a6 classical featurχ e in geomaterials, which exhibit higher strength in triaxial where s = σ p δ is the deviatoriccomcomppresonsion.ent of thFigue effreectiv3 ealsostressreteflenctssor,theand geχ =ome√trtrsical2. interpretation for parameters M and N − The invariant p is the mean normalwhiceffectivh goe vstresernstheandslopis asseuofmedthtoe CbeSLnegatiandveththre coughurvaturout.
Load more

Recommended publications
  • Step 2-Soil Mechanics
    Step 2 – Soil Mechanics Introduction Webster defines the term mechanics as a branch of physical science that deals with energy and forces and their effect on bodies. Soil mechanics is the branch of mechanics that deals with the action of forces on soil masses. The soil that occurs at or near the surface of the earth is one of the most widely encountered materials in civil, structural and architectural engineering. Soil ranks high in degree of importance when compared to the numerous other materials (i.e. steel, concrete, masonry, etc.) used in engineering. Soil is a construction material used in many structures, such as retaining walls, dams, and levees. Soil is also a foundation material upon which structures rest. All structures, regardless of the material from which they are constructed, ultimately rest upon soil or rock. Hence, the load capacity and settlement behavior of foundations depend on the character of the underlying soils, and on their action under the stress imposed by the foundation. Based on this, it is appropriate to consider soil as a structural material, but it differs from other structural materials in several important aspects. Steel is a manufactured material whose physical and chemical properties can be very accurately controlled during the manufacturing process. Soil is a natural material, which occurs in infinite variety and whose engineering properties can vary widely from place to place – even within the confines of a single construction project. Geotechnical engineering practice is devoted to the location of various soils encountered on a project, the determination of their engineering properties, correlating those properties to the project requirements, and the selection of the best available soils for use with the various structural elements of the project.
    [Show full text]
  • Soil Mechanics Lectures Third Year Students
    2016 -2017 Soil Mechanics Lectures Third Year Students Includes: Stresses within the soil, consolidation theory, settlement and degree of consolidation, shear strength of soil, earth pressure on retaining structure.: Soil Mechanics Lectures /Coarse 2-----------------------------2016-2017-------------------------------------------Third year Student 2 Soil Mechanics Lectures /Coarse 2-----------------------------2016-2017-------------------------------------------Third year Student 3 Soil Mechanics Lectures /Coarse 2-----------------------------2016-2017-------------------------------------------Third year Student Stresses within the soil Stresses within the soil: Types of stresses: 1- Geostatic stress: Sub Surface Stresses cause by mass of soil a- Vertical stress = b- Horizontal Stress 1 ∑ ℎ = ͤͅ 1 Note : Geostatic stresses increased lineraly with depth. 2- Stresses due to surface loading : a- Infintly loaded area (filling) b- Point load(concentrated load) c- Circular loaded area. d- Rectangular loaded area. Introduction: At a point within a soil mass, stresses will be developed as a result of the soil lying above the point (Geostatic stress) and by any structure or other loading imposed into that soil mass. 1- stresses due Geostatic soil mass (Geostatic stress) 1 = ℎ , where : is the coefficient of earth pressure at # = ͤ͟ 1 ͤ͟ rest. 4 Soil Mechanics Lectures /Coarse 2-----------------------------2016-2017-------------------------------------------Third year Student EFFECTIVESTRESS CONCEPT: In saturated soils, the normal stress ( σ) at any point within the soil mass is shared by the soil grains and the water held within the pores. The component of the normal stress acting on the soil grains, is called effective stressor intergranular stress, and is generally denoted by σ'. The remainder, the normal stress acting on the pore water, is knows as pore water pressure or neutral stress, and is denoted by u.
    [Show full text]
  • Hydrologic Processes in Vertisols
    the united nations educational, scientific abdus salam and cultural organization international centre for theoretical physics ternational atomic energy agency H4.SMR/1304-11 "COLLEGE ON SOIL PHYSICS" 12 March - 6 April 2001 Hydrologic Processes in Vertisols M. Kutilek and D. R. Nielsen Elsevier Soil and Tillage Research (Journal) Prague Czech Republic These notes are for internal distribution onlv strada costiera, I I - 34014 trieste italy - tel.+39 04022401 I I fax +39 040224163 - [email protected] - www.ictp.trieste.it College on Soil Physics ICTP, TRIESTE, 12-29 March, 2001 LECTURE NOTES Hydrologic Processes in Vertisols Extended text of the paper M. Kutilek, 1996. Water Relation and Water Management of Vertisols, In: Vertisols and Technologies for Their Management, Ed. N. Ahmad and A. Mermout, Elsevier, pp. 201-230. Miroslav Kutilek Professor Emeritus Nad Patankou 34, 160 00 Prague 6, Czech Republic Fax/Tel +420 2 311 6338 E-mail: [email protected] Developments in Soil Science 24 VERTISOLS AND TECHNOLOGIES FOR THEIR MANAGEMENT Edited by N. AHMAD The University of the West Indies, Faculty of Agriculture, Depart, of Soil Science, St. Augustine, Trinidad, West Indies A. MERMUT University of Saskatchewan, Saskatoon, sasks. S7N0W0, Canada ELSEVIER Amsterdam — Lausanne — New York — Oxford — Shannon — Tokyo 1996 43 Chapter 2 PEDOGENESIS A.R. MERMUT, E. PADMANABHAM, H. ESWARAN and G.S. DASOG 2.1. INTRODUCTION The genesis of Vertisols is strongly influenced by soil movement (contraction and expansion of the soil mass) and the churning (turbation) of the soil materials. The name of Vertisol is derived from Latin "vertere" meaning to turn or invert, thus limiting the development of classical soil horizons (Ahmad, 1983).
    [Show full text]
  • 2001 01 0122.Pdf
    INTERNATIONAL SOCIETY FOR SOIL MECHANICS AND GEOTECHNICAL ENGINEERING This paper was downloaded from the Online Library of the International Society for Soil Mechanics and Geotechnical Engineering (ISSMGE). The library is available here: https://www.issmge.org/publications/online-library This is an open-access database that archives thousands of papers published under the Auspices of the ISSMGE and maintained by the Innovation and Development Committee of ISSMGE. Soil classification: a proposal for a structural approach, with reference to existing European and international experience Classification des sols: une proposition pour une approche structurelle, tenant compte de l’expérience Européenne et internationale lr. Gauthier Van Alboom - Geotechnics Division, Ministry of Flanders, Belgium ABSTRACT: Most soil classification schemes, used in Europe and all over the world, are of the basic type and are mainly based upon particle size distribution and Atterberg limits. Degree of harmonisation is however moderate as the classification systems are elabo­ rated and / or adapted for typical soils related to the country or region considered. Proposals for international standardisation have not yet resulted in ready for use practical classification tools. In this paper a proposal for structural approach to soil classification is given, and a basic soil classification system is elaborated. RESUME: La plupart des méthodes de classification des sols, en Europe et dans le monde entier, sont du type de base et font appel à la distribution des particules et aux limites Atterberg. Le degré d’harmonisation est cependant modéré, les systèmes de classification étant élaborés et / ou adaptés aux sols qui sont typiques pour le pays ou la région considérée.
    [Show full text]
  • Processes in the Unsaturated Zone by Reliable Soil Water Content
    sustainability Article Processes in the Unsaturated Zone by Reliable Soil Water Content Estimation: Indications for Soil Water Management from a Sandy Soil Experimental Field in Central Italy Lucio Di Matteo * , Alessandro Spigarelli and Sofia Ortenzi Dipartimento di Fisica e Geologia, Università degli Studi di Perugia, Via Pascoli s.n.c., 06123 Perugia, Italy; [email protected] (A.S.); sofi[email protected] (S.O.) * Correspondence: [email protected]; Tel.: +39-0755-849-694 Abstract: Reliable soil moisture data are essential for achieving sustainable water management. In this framework, the performance of devices to estimate the volumetric moisture content by means dielectric properties of soil/water system is of increasing interest. The present work evaluates the performance of the PR2/6 soil moisture profile probe with implications on the understanding of processes involving the unsaturated zone. The calibration at the laboratory scale and the validation in an experimental field in Central Italy highlight that although the shape of the moisture profile is the same, there are essential differences between soil moisture values obtained by the calibrated equation and those obtained by the manufacturer one. These differences are up to 10 percentage points for fine-grained soils containing iron oxides. Inaccurate estimates of soil moisture content do not help with understanding the soil water dynamic, especially after rainy periods. The sum of antecedent soil moisture conditions (the Antecedent Soil moisture Index (ASI)) and rainfall related to different stormflow can be used to define the threshold value above which the runoff significantly increases. Without an accurate calibration process, the ASI index is overestimated, thereby affecting the threshold evaluation.
    [Show full text]
  • Automatic Soil Identification from Remote Sensing Data
    DR. KAM W. WONG University of-Illinois at Urbana-C hampaign Urbana, IL 61801 DR. T. H. THORNBUR Las Vegas, NV 89109 M. A. KHOURY University of Illinois at Urbana-Champaign Urbana, IL 61801 Automatic Soil Identification from Remote Sensing Data Small differences in soil types can be distinguished by the use of quantitative terrain factors which are computed from digital terrain data. INTRODUCTION pends primarily on the ability of the in­ HE CHARACTERISTICS of a soil and by terpreter, and (3) they are relatively time­ T extension its engineering properties are consuming. With the advance of electronic chiefly a function of the parent material, to­ computers and the corresponding develop­ pography, vegetation, climate, and time. ments in automatic topographic mapping Thus, having a thorough understanding of and remote sensing, the automation of soil geomorphology and the natural forces ofero­ classification has become an interesting as sion and weathering such as wind, ice, and well as promising possibility. water, a soil scientist experienced in air This paper describes a systems approach photo interpretation techniques can identify for the automatic identification of soils by soil characteristics from the land forms, ero- the combined application of remote sensing ABSTRACT: A reliable method ofautomatic soil identification can be developed by the combined application ofremote sensing and digital terrain data. Research results have demonstrated that small differ­ ences in soil types can be distinguished by the use of quantitative terrain factors which are computed from digital terrain data. Con­ tinuing research effort is dil-ected towards the improvement of the terrain factors, the development ofstatistical prediction techniques, and testing the effectiveness ofthese factors in the identification of soils.
    [Show full text]
  • Cutting Soil Mechanics
    Dredging Processes The Cutting of Sand, Clay & Rock Soil Mechanics Dr.ir. Sape A. Miedema The Cutting of Sand, Clay & Rock - Soil Mechanics Copyright © Dr.ir. S.A. Miedema Page 3 of 64 The Cutting of Sand, Clay & Rock - Soil Mechanics Dredging Processes The Cutting of Sand, Clay & Rock Soil Mechanics By Dr.ir. Sape A. Miedema Copyright © Dr.ir. S.A. Miedema Page 4 of 64 The Cutting of Sand, Clay & Rock - Soil Mechanics Dredging Processes The Cutting of Sand, Clay & Rock Soil Mechanics Copyright © Dr.ir. S.A. Miedema Page 5 of 64 The Cutting of Sand, Clay & Rock - Soil Mechanics Preface Lecture notes for the course OE4626 Dredging Processes, for the MSc program Offshore & Dredging Engineering, at the Delft University of Technology. By Dr.ir. Sape A. Miedema, Sunday, January 13, 2013 In dredging, trenching, (deep sea) mining, drilling, tunnel boring and many other applications, sand, clay or rock has to be excavated. The productions (and thus the dimensions) of the excavating equipment range from mm3/sec - cm3/sec to m3/sec. In oil drilling layers with a thickness of a magnitude of 0.2 mm are cut, while in dredging this can be of a magnitude of 0.1 m with cutter suction dredges and meters for clamshells and backhoe’s. Some equipment is designed for dry soil, while others operate under water saturated conditions. Installed cutting powers may range up to 10 MW. For both the design, the operation and production estimation of the excavating equipment it is important to be able to predict the cutting forces and powers.
    [Show full text]
  • Soil Mechanics
    Soil Mechanics Soil is the most misunderstood term in the field. The problem arises in the reasons for which different groups or professions study soils. Soil scientists are interested in soils as a medium for plant growth. So soil scientists focus on the organic rich part of the soils horizon and refer to the sediments below the weathered zone as parent material. Classification is based on physical, chemical, and biological properties that can be observed and measured. Soils engineers think of a soil as any material that can be excavated with a shovel (no heavy equipment). Classification is based on the particle size, distribution, and the plasticity of the material. These classification criteria more relate to the behavior of soils under the application of load - the area where we will concentrate. Soil Mechanics Most geologists fall somewhere in between. Geologists are interested in soils and weathering processes as indicators of past climatic conditions and in relation to the geologic formation of useful materials ranging from clay to metallic ore deposits. Geologists usually refer to any loose material below the plant growth zone as sediment or unconsolidated material. The term unconsolidated is also confusing to engineers because consolidation specifically refers to the compression of saturated soils in soils engineering. 1 Soil Mechanics Engineering Properties of Soil The engineering approach to the study of soil focuses on the characteristics of soils as construction materials and the suitability of soils to withstand the load applied by structures of various types. Weight-Volume Relationship Earth materials are three-phase systems. In most applications, the phases include solid particles, water, and air.
    [Show full text]
  • An Improved Volume Measurement for Determining Soil Water Retention Curves
    Geotechnical Testing Journal, Vol. 30, No. 1 Paper ID GTJ100167 Available online at: www.astm.org Hervé Péron,1 Tomasz Hueckel,2 and Lyesse Laloui1 An Improved Volume Measurement for Determining Soil Water Retention Curves ABSTRACT: The complete determination of soil water retention curves requires the sample volume to be measured in order to calculate its void ratio and degree of saturation. During drying in the pressure plate apparatus, cracks often appear in the sample altering its deformation and evapo- ration patterns. Consequently, this causes a significant scatter in the volume measurement when using the volume displacement method. This paper proposes a simple method to avoid cracking, by limiting friction and adhesion boundary effects, to allow for unrestrained shrinkage of the sample. Such modification of the technique decreases the measurement error by a factor of three. KEYWORDS: soil water retention curve, friction, shrinkage, cracks, volume measurement accuracy Background sample deformation induced by suction is sensitive to the displace- ment boundary conditions ͑Sibley and Williams, 1989͒. The soil water retention curve defines the relationship between The volume measurement in the pressure plate apparatus is per- gravimetric or volumetric water content, w, ͑or degree of satura- formed on an unconfined sample under zero mechanical stress and ͒ ͑ ͒ tion, Sr, or void ratio, e and soil suction, s Barbour 1998 . The is achieved not without some difficulties as indicated by Geiser reliability in the determination of the soil-water retention curve is ͑1999͒, who compared various volume measurement methods on of great interest in unsaturated soil engineering practice, as suction unconfined samples.
    [Show full text]
  • Geotechnical Analysis of Optimal Parameters for Foundations Interacting with Loess Area
    E3S Web of Conferences 168, 00024 (2020) https://doi.org/10.1051/e3sconf/202016800024 RMGET 2020 Geotechnical analysis of optimal parameters for foundations interacting with loess area Olha Dubinchyk1,∗, Dmytro Bannikov1, Vitalii Kildieiev1, and Vitalii Kharchenko1 1Dnipro National University of Railway Transport named after Academician V. Lazaryan, 49010, Dnipro, Lazaryan Str., 2, Ukraine Abstract. The article highlights results of the geotechnical analysis of the stress and strain state for the base of a subsoil massif under its interaction with the strip foundations. The massif is represented by loess soils which while soaking give overtime subsidences that complicate the operation of a building or a structure. Through geotechnical iterative research, optimization of the parameters for strip foundations on four axes at a four- storeyed residential building is carried out. Checks are performed on two groups of limiting states for scenarios of soil occurrence in natural, moistened and compacted states. The optimum dimensions in the width of strip foundations are selected, they give approximately the same strain values of the base after the creation of the soil bedding with its layer-by- layer compaction. The relevance of this research is to develop optimal parameters in the design of strip foundations for shallow depth on subsidental loess soils. 1 Introduction Geomechanics, as a science, combining the mechanics of rocks and underground structures tends to analyze workings and structures that lie in sufficiently hard rocks at deep depths [1]. Geotechnics, based on soil mechanics and structural mechanics, examines structures affecting the weak massifs formed by soils [2]. Given all the differences between these varieties of Earth science, one should determine the main conceptual feature that unites them.
    [Show full text]
  • Petrographic and Engineering Properties of Loess
    BNGINEERING MONOGRAPHS No. 28 United States Department of the Interior BUREAU OF RECLAMATION PETROGRAPHIC AND ENGINEERING PROPERTIES OF LOESS by H. J. Gibbs and W. Y. Holland November 1960 $1.00 ~ BUREAU OF RfCLAMA nON l' Cr~~ DENVER UBf!ARY If t (/l I'I'II~'IIIII~/II"~III'920251b3 tl J t, \r , ;;"" 1; "," I. I ,' ;' ~'", r '.'" United States Department of the Interior 'Jo' 0 I .'.~!1 .~ j FRED A. SEA TON, Secretary Bureau of Reclamation FLOYD E. DOMINY, COMMISSIONER GRANT BLOODGOOD, Assistant Commissioner and Chief Engineer Engineering Monograph No. 28 PETROGRAPHIC AND ENGINEERING PROPERTIES OF LOESS by H. J. Gibbs, Head, Special Investigations and Research Section Earth Laboratory Branch and W. Y. Holland, Head, Petrographic Laboratory Section, Chemical Engineering Laboratory Branch Commissioner's Office, Denver, Colorado Technical Information Branch Denver Federal Center Denver, Colorado ENGINEERING MONOGRAPHS are published in lirnit~d ~@ition~for till! tl!chnicA.l !t!.ff of the Bureau of Reclamation and interested technical circles in Government and private agencies. Their purpose is to record devel- opments, innovations, and progress in the engineering and scientific techniques and practices that are employed in the planning, design, construction, and operation of Recla- mation structures and equipment. Copies may be obtained from the Bureau of Recla- mation' Denver Federal Center, Denver, Colorado, and Washington, D. C. CONTENTS Page INTRODUCTION. 1 GENERAL DESCRIPTION OF LOESS. 1 ORIGIN OF LOESS. 4 DETAILED DESCRIPTION OF LOESS. 6 Type of Matrix. 7 Cementation. 8 Particle Shape. 8 Granular Components. 9 Grain Coatings. 9 OBSERVATION OF PHYSICAL PROPERTIES. 9 Location of Engineering Studies.
    [Show full text]
  • Downloaded from the Online Library of the International Society for Soil Mechanics and Geotechnical Engineering (ISSMGE)
    INTERNATIONAL SOCIETY FOR SOIL MECHANICS AND GEOTECHNICAL ENGINEERING This paper was downloaded from the Online Library of the International Society for Soil Mechanics and Geotechnical Engineering (ISSMGE). The library is available here: https://www.issmge.org/publications/online-library This is an open-access database that archives thousands of papers published under the Auspices of the ISSMGE and maintained by the Innovation and Development Committee of ISSMGE. Proceedings of the 16th International Conference on Soil Mechanics and Geotechnical Engineering © 2005–2006 Millpress Science Publishers/IOS Press. Published with Open Access under the Creative Commons BY-NC Licence by IOS Press. doi:10.3233/978-1-61499-656-9-773 Determination of the mechanical characteristics of soils by results of plate load tests Définition des caractéristiques mécaniques des sols d'après les resultats des tests estampés A.Zh.Zhusupbekov & A.S. Zhakulin Geotechnical Institute, L.N. Gumilyev Eurasian National University, Astana, Kazakhstan H.Z. Bakenov Interparliamentary Assambley of CIS, St. Petersburg, Russia ABSTRACT The complex of field researches by plate load tests on loamy and loam sandy soils of water-saturated bases on the construction site of New Airport Astana have been carried out by the authors. The means for reconstruction of the airport in capital of Kazakhstan are allocated as the grant by Japanese Bank for Development and Reconstruction, and also the Japan company "Marubeni" taking active part in the construction. And also the spatial task by a method of final elements for estimation of stressed – deformed condition of water-saturated bases is solved. The elastic and plastic model of soil, supposing elastic work within the limits of surface, described by criterion Mor-Kulon and coextensive current on this surface is considered.
    [Show full text]