DOCSLIB.ORG

Geotechnical Engineering Report ______

Total Page：16

File Type：pdf, Size：1020Kb

Download full-text PDF Read full-text
Geotechnical Engineering Report ______ REPORT COVER PAGE Geotechnical Engineering Report __________________________________________________________________________ Yeader Creek Stabilization Improvements Des Moines, Iowa December 12, 2018 Terracon Project No. 08175152-01 Prepared for: HR Green, Inc. Johnston, Iowa Prepared by: Terracon Consultants, Inc. Des Moines, Iowa REPORT COVER LET TER T O SIGN December 12, 2018 HR Green, Inc. 5525 Merle Hay Road, Suite 200 Johnston, Iowa 50131 Attn: Mr. Chad Mason, P.E. P: (636) 812-4210 E: [email protected] Re: Geotechnical Engineering Report Yeader Creek Stabilization Improvements Des Moines, Iowa Terracon Project No. 08175152-01 Dear Mr. Mason: We have performed geotechnical engineering services for the referenced project in general accordance with the Standard Agreement for Subconsultant Services, HR Green Project No. 170850, dated September 14, 2018. After the initial field exploration was completed, the locations of proposed improvements was altered, Terracon received approval for an additional three borings via email on November 13, 2018. This report presents the findings of the subsurface exploration and provides geotechnical considerations and recommendations concerning the proposed channel improvements along the applicable portions of the Yeader Creek tributaries. We appreciate the opportunity to be of service to you on this project. If you have any questions concerning this report, or if we may be of further service, please contact us. Sincerely, Terracon Consultants, Inc. Theodore D. Bechtum, P.E. Brett E. Bradfield, P.E. Project Engineer Senior Engineering Consultant Terracon Consultants, Inc. 600 SW 7th Street, Suite M Des Moines, Iowa 50309 P (515) 244 3184 F (515) 244 5249 terracon.com REPORT TOPICS INTRODUCTION ............................................................................................................. 2 SITE CONDITIONS ......................................................................................................... 2 PROJECT DESCRIPTION .............................................................................................. 4 GEOTECHNICAL CHARACTERIZATION ...................................................................... 5 GRAVITY RETAINING WALLS ...................................................................................... 6 STABILITY ANALYSES ................................................................................................. 8 EARTHWORK............................................................................................................... 16 ENVIRONMENTAL CONSIDERATIONS ...................................................................... 20 GENERAL COMMENTS ............................................................................................... 20 SIGNATURE PAGE ...................................................................................................... 21 ATTACHMENTS ........................................................................................................... 22 Note: This report was also delivered in a web-based format. For more interactive features, please view your project online at client.terracon.com. ATTACHMENTS EXPLORATION AND TESTING PROCEDURES SITE LOCATION AND EXPLORATION PLANS EXPLORATION RESULTS SUPPORTING INFORMATION Note: Refer to each individual Attachment for a listing of contents. Responsive ■ Resourceful ■ Reliable INTRODUC TION Geotechnical Engineering Report Yeader Creek Stabilization Improvements Des Moines, Iowa Terracon Project No. 08175152-01 December 12, 2018 INTRODUCTION Geotechnical engineering exploration and analysis has been completed for the evaluation of portions of the creek stabilization improvements proposed on the Yeader Creek tributaries in Des Moines, Iowa. The exploration consisted of 8 geotechnical borings to depths ranging from approximately 20 to 30 feet below existing ground surface (bgs) and 6 hand auger borings to depths ranging from approximately 5 to 13 feet bgs. The purpose of these services is to provide information, professional opinions, and/or geotechnical recommendations relative to: ■ Subsurface soil and rock conditions ■ Groundwater conditions ■ Cursory slope stability evaluation of ■ Earthwork and subgrade preparation planned improvements ■ Bearing conditions for planned improvements Maps showing the sites along the channel and boring locations are shown in the Site Location and Exploration Plan section. The results of the laboratory testing performed on soil samples obtained from the sites during the field exploration are included on the boring logs and/or as separate graphs in Exploration Results. SITE CONDITIONS The following description of site conditions is derived from our site visit in association with the field exploration and our review of publicly available geologic and topographic maps. Item Description Exploration was requested by HR Green in the following areas: See Site Location and Exploration Plan ■ Area 1: North of Yeader Creek and south of 511 Titus Avenue (Vicinity of Boring 1) Location ■ Area 2 (Wall shown on Sheet V.01): East of Yeader Creek tributary and west of 5310 and 5304 SE 5th Street (Vicinity of Boring 2, 3 and 4). ■ Area 3 (Wall shown on Sheet V.02): South of Yeader Creek and west of Yeader creek tributary near 5201 South Union Street (Vicinity Boring 5, 6, and 12) Responsive ■ Resourceful ■ Reliable 2 Geotechnical Engineering Report Yeader Creek Stabilization Improvements ■ Des Moines, Iowa December 12, 2018 ■ Terracon Project No. 08175152-01 Item Description ■ Area 4 (Wall shown on Sheet V.03): East of Yeader Creek Tributary and west of 100 East Kenyon Avenue (Vicnity of Boring 7 and 13) ■ Area 5: Yeader Creek Tributary, east of 17 East Kenyon Avenue (Vicinity of Boring 8) ■ Area 6: West of Yeader Creek Tributary and east of 5513 South Union Street (Vicinity of Boring 9 and 10). ■ Area 7 (Wall shown on Sheet V.04): East of Yeader Creek Tributary and west of 5512 Southeast 1st Court (Vicinity of Boring 11 and 14) Existing conditions generally consist of eroded stream banks near the Current Ground existing creek. Vegetation consists of trees, shrubs, and grass, with reduced Cover vegetation in areas of recent erosion. In general, the area outside the creek banks has relatively flat or rolling topography in areas with minor erosion. Near the stream, the ground slopes relatively steeply to the existing stream, often creating a ravine, with occasional indications of prior bank failures. Elevations and apparent slopes interpreted from the information provided by Nilles and HR Green are provided below: The ground slopes vary along the waterways with areas of nearly vertical slopes, and the following descriptions are only an approximate indication of actual conditions. ■ Area 1: Creek flow line elevation of about 53 feet (City of Des Moines datum). North bank has apparent 0.5:1 (horizontal : vertical) slope with elevation of about 66 feet at top of slope. South bank has apparent 1.5:1 slope with elevation of about 60 feet at top of slope. ■ Area 2 (Wall shown on Sheet V.01): Creek flow line elevations of about 72 to 77 feet. East and west creek banks generally have a 1.5:1 slope, with areas steeper than 1:1. The elevation is about 88 to 91 feet at top Existing Topography of east slope and 83 feet at top of west slope. ■ Area 3 (Wall shown on Sheet V.02): Creek flow line elevation of about 69 to 72 feet. West creek bank generally has a slope of about 3:1, with areas steeper than 1:1 near the steam channel. The elevation is about 86 feet at the top of the west slope. ■ Area 4 (Wall shown on Sheet V.03): Creek flow line elevation of about 77 feet. East and west creek banks generally have slopes of about 1:1 or 1.5:1, with areas steeper than 1:1. The elevation is about 93 feet at the top of the east slope and about 95 feet at the top of the west slope. ■ Area 5: Creek flow line elevation of about 82 to 83 feet. West and east bank has an apparent 1:1 slope with elevation of about 100 feet at top of west bank and 92 feet at top of east bank. ■ Area 6: Creek flow line elevation of about 86 to 90 feet. West bank has apparent 1:1 slope or steeper with elevation of about 95 to 100 feet at top of slope. Responsive ■ Resourceful ■ Reliable 3 Geotechnical Engineering Report Yeader Creek Stabilization Improvements ■ Des Moines, Iowa December 12, 2018 ■ Terracon Project No. 08175152-01 Item Description ■ Area 7 (Wall shown on Sheet V.04): Creek flow line elevation of about Existing Topography 86 to 90 feet. East bank has an apparent 1.5:1 to 1:1 slope, with areas (cont.) steeper than 1:1. The elevation is about 100 feet at top of east slope. Rip rap has been placed in occasional locations of erosion or bank collapses or sloughing, and debris and refuse was occasionally encountered at the Current streambank ground surface and/or embedded in the banks. Much of the existing stream distress bank is anticipated to be prone to potential instability with increases in pore water pressure, possibly due to rain events, and scour and erosion/removal of material at base of creek. PROJECT DESCRIPTION Item Description Based on meetings with HR Green, Terracon understands gravity walls will be considered at Areas 2, 3, 4, and 7. Information at each of the walls was provided on the V Sheets provided by HR Green, dated October 18, 2018. ■ Area 2 (Wall shown on Sheet V.01): Proposed gravity wall with height of about 7 feet or less and length of about 160 feet on the east side of Yeader Creek behind 5304 and 5310 SE 5th Street. ■ Area 3 (Wall shown on Sheet
Load more

Recommended publications
  • Linktm Gabions and Mattresses Design Booklet
    LinkTM Gabions and Mattresses Design Booklet www.globalsynthetics.com.au Australian Company - Global Expertise Contents 1. Introduction to Link Gabions and Mattresses ................................................... 1 1.1 Brief history ...............................................................................................................................1 1.2 Applications ..............................................................................................................................1 1.3 Features of woven mesh Link Gabion and Mattress structures ...............................................2 1.4 Product characteristics of Link Gabions and Mattresses .........................................................2 2. Link Gabions and Mattresses .............................................................................. 4 2.1 Types of Link Gabions and Mattresses .....................................................................................4 2.2 General specification for Link Gabions, Link Mattresses and Link netting...............................4 2.3 Standard sizes of Link Gabions, Mattresses and Netting ........................................................6 2.4 Durability of Link Gabions, Link Mattresses and Link Netting ..................................................7 2.5 Geotextile filter specification ....................................................................................................7 2.6 Rock infill specification .............................................................................................................8
    [Show full text]
  • Determination of Earth Pressure Distributions for Large-Scale Retention Structures
    DETERMINATION OF EARTH PRESSURE DISTRIBUTIONS FOR LARGE-SCALE RETENTION STRUCTURES J. David Rogers, Ph.D., P.E., R.G. Geological Engineering University of Missouri-Rolla DETERMINATION OF EARTH PRESSURE DISTRIBUTIONS FOR LARGE-SCALE RETENTION STRUCTURES 1.0 Introduction Various earth pressure theories assume that soils are homogeneous, isotropic and horizontally inclined. These assumptions lead to hydrostatic or triangular pressure distributions when calculating the lateral earth pressures being exerted against a vertical plane. Field measurements on deep retained excavations have shown that the average earth pressure load is approximately uniform with depth with small reductions at the top and bottom of the excavation. This type of distribution was first suggested by Terzaghi (1943) on the basis of empirical data collected on the Berlin Subway and Chicago Subway projects between 1936-42. Since that time, it has been shown that this uniform distribution only occurs when the following conditions are met: 1. The upper portions of the vertical side walls of the excavation are supported in stages as the excavation is deepened; 2. The walls of the excavation are pervious enough so that water pressure does not build up behind them; and 3. The lateral movements of the walls are kept below 1% to 2% of the depth of the excavation. With the passage of time, the approximately uniform pressure distribution evidenced during construction has been observed to transition toward the more traditional triangular distribution. In addition, it has been found that the tie-back force in anchored bulkhead walls generally increases with time. The actual load imposed on a semi-vertical retaining wall is dependent on eight aspects of its construction: 1.
    [Show full text]
  • Retaining Wall Building Permit Requirements
    Retaining Wall Building Permit Requirements This guideline is intended to provide the homeowner/contractor with the basic information needed to apply for a building permit to construct residential retaining walls. These requirements apply to most simple retaining wall projects; however, the Plan Reviewer may determine that unusual circum- stance dictates the need for additional information on any particular project. Phone (314) 822-5823 Building Department 139 S. Kirkwood Rd Fax (314) 822-5898 www.kirkwoodmo.org Kirkwood, MO 63122 Complete cross-sectional drawing of wall Plans for small residential retaining walls A permit is required for any to scale. complying with the design criteria below retaining wall that is more than 2' in may be drawn by the homeowner/ height above the lowest adjacent Elevation view from the low grade side of contractor: (Note: The walls shall not be grade and for retaining walls of any wall drawn to scale. subject to any surcharge loading from steep height located in a natural water slopes, driveways, swimming pools and course or drainage swale. Guardrail details if applicable. Retaining other structures, etc.) walls more than 30”measured vertically to the grade below at any point within The proposed retaining wall is located on a 1. Fill out and sign application for a building 36” horizontally to the edge of the open parcel of land containing a one or two permit. side; are required to have a guardrail or family dwelling. other approved protective measure when 2. Submit two (2) separate copies of your site closer than 2’ to a sidewalk, path, Wood retaining walls not exceeding 6' in plan showing existing structures with the new parking area or driveway on the high height for single tier or 4' in height for retaining wall and its perpendicular distances side.
    [Show full text]
  • Guide to Retaining Wall Design, 1St Editionthis Link Will Open in New Window
    FOREWORD This Guide to Retaining Wall Design is the first Guide to be produced by the Geotechnical Control Office. It will be found useful to those engaged upon the design and construction of retaining walls and other earth retaining structures in Hong Kong and, to a lesser extent, elsewhere. This Guide should best be read in conjunction with the Geotechnical Manual for Slopes (Geotechnical Control Office, 1979), to which extensive reference is made. The Guide has been modelled largely on the Retaining Wall Design Notes published by the Ministry of Works and Development, New Zealand (1973), and the extensive use of that document is acknowledged. Many parts of that document, however, have been considerably revised and modified to make them more specifically applicable to Hong Kong conditions. In this regard, it should be noted that the emphasis in the Guide is on design methods which are appropriate to the residual soils prevalent in Hong Kong. Many staff members of the Geotechnical Control Office have contributed in some way to the preparation of this Guide, but the main contributions were made by Mr. J.C. Rutledge, Mr. J.C. Shelton, and Mr. G.E. Powell. Responsibility for the statements made in this document, however, lie with the Geotechnical Control Office. It is hoped that practitioners will feel free to comment on the content of this Guide to Retaining Wall Design, so that additions and improvements can be made to future editions. E.W. Brand Principal Government Geotechnical Engineer Printed September 1982 1st Reprint January 1983
    [Show full text]
  • Design of Riprap Revetment HEC 11 Metric Version
    Design of Riprap Revetment HEC 11 Metric Version Welcome to HEC 11-Design of Riprap Revetment. Table of Contents Preface Tech Doc U.S. - SI Conversions DISCLAIMER: During the editing of this manual for conversion to an electronic format, the intent has been to convert the publication to the metric system while keeping the document as close to the original as possible. The document has undergone editorial update during the conversion process. Archived Table of Contents for HEC 11-Design of Riprap Revetment (Metric) List of Figures List of Tables List of Charts & Forms List of Equations Cover Page : HEC 11-Design of Riprap Revetment (Metric) Chapter 1 : HEC 11 Introduction 1.1 Scope 1.2 Recognition of Erosion Potential 1.3 Erosion Mechanisms and Riprap Failure Modes Chapter 2 : HEC 11 Revetment Types 2.1 Riprap 2.1.1 Rock Riprap 2.1.2 Rubble Riprap 2.2 Wire-Enclosed Rock 2.3 Pre-Cast Concrete Block 2.4 Grouted Rock 2.5 Paved Lining Chapter 3 : HEC 11 Design Concepts 3.1 Design Discharge 3.2 Flow Types 3.3 Section Geometry 3.4 Flow in Channel Bends 3.5 Flow Resistance 3.6 Extent of Protection 3.6.1 Longitudinal Extent 3.6.2 Vertical Extent 3.6.2.1 Design Height 3.6.2.2 Toe Depth Chapter 4 : HEC 11 Design Guidelines for Rock Riprap 4.1 Rock Size Archived 4.1.1 Particle Erosion 4.1.1.1 Design Relationship 4.1.1.2 Application 4.1.2 Wave Erosion 4.1.3 Ice Damage 4.2 Rock Gradation 4.3 Layer Thickness 4.4 Filter Design 4.4.1 Granular Filters 4.4.2 Fabric Filters 4.5 Material Quality 4.6 Edge Treatment 4.7 Construction Chapter 5 : HEC 11 Rock
    [Show full text]
  • Subway Station Retaining Walls: Case-Histories in Soft and Hard Soils
    Subway station retaining walls: case-histories in soft and hard soils Vardé, O.(1), Guidobono, R.(2), and Sfriso, A.(3) (1) President, National Academy of Engineering, Buenos Aires, Argentina <[email protected] > (2) Vardé y Asociados, Buenos Aires, Argentina <[email protected]> (3) University of Buenos Aires and SRK Consulting, Buenos Aires, Argentina <[email protected]> ABSTRACT. In the last twenty years, sixteen pile-supported metro stations have been built in Buenos Aires in a wide range of geotechnical conditions. After an initial design of the construction procedures including partial open-trench (in two cases), all subsequent fourteen stations were excavated employing cut&cover techniques. In all cases, vertical bored piles were employed both to support the lateral ground pressure and the loads acting on the roof slab. This paper revisits the geotechnical conditions in Buenos Aires City, describes the procedures employed for the design and numerical analysis of pile-supported excavations and presents the behavior of five recent cases located in widely different geotechnical profiles. The paper ends with a summary of lessons learned which are relevant both for design and construction. 1 INTRODUCTION Buenos Aires metro network opened in 1913, being the first one in the southern hemisphere. Figure 1 shows the excavation procedure for Line A in 1911 (SBASE 2017). Expansion was fast until the 40’s, when it halted for until it was resumed in the late 90’s. The network is formed by six lines, 55km of tunnels and 86 stations, and complemented by two surface lines (Figure 1). Figure 1.
    [Show full text]
  • A Review of GPR Application on Transport Infrastructures: Troubleshooting and Best Practices
    remote sensing Review A Review of GPR Application on Transport Infrastructures: Troubleshooting and Best Practices Mercedes Solla 1,* , Vega Pérez-Gracia 2 and Simona Fontul 3,4 1 CINTECX, GeoTECH research group, Universidade de Vigo, 36310 Vigo, Spain 2 Department of Strength of Materials and Structural Engineering, Universitat Politècnica de Catalunya, Campus Diagonal Besós, Barcelona East School of Engineering, EEBE, Av. Eduard Maristany, 16, 08019 Barcelona, Spain; [email protected] 3 Department of Transportation, National Laboratory for Civil Engineering—LNEC, 1700-066 Lisbon, Portugal; [email protected] 4 Civil Engineering Department, NOVA School of Science and Technology, 2829-516 Caparica, Portugal * Correspondence: [email protected] Abstract: The non-destructive testing and diagnosis of transport infrastructures is essential because of the need to protect these facilities for mobility, and for economic and social development. The effective and timely assessment of structural health conditions becomes crucial in order to assure the safety of the transportation system and time saver protocols, as well as to reduce excessive repair and maintenance costs. Ground penetrating radar (GPR) is one of the most recommended non-destructive methods for routine subsurface inspections. This paper focuses on the on-site use of GPR applied to transport infrastructures, namely pavements, railways, retaining walls, bridges and tunnels. The methodologies, advantages and disadvantages, along with up-to-date research results on GPR in infrastructure inspection are presented herein. Hence, through the review of the published literature, the potential of using GPR is demonstrated, while the main limitations of the method are discussed and some practical recommendations are made. Citation: Solla, M.; Pérez-Gracia, V.; Fontul, S.
    [Show full text]
  • Mr. Yard, Inc. “How-To” for a Rip Rap Wall
    Mr. Yard, Inc. 8997 Columbia Rd., Olmsted Falls, OH 44138 p. (440) 235-2358 f. (440) 235-2359 [email protected] www.mryardoh.com “How-To” for a Rip Rap Wall Retaining walls are built to prevent soil from being lost due to erosion or displacement down a slope. Once built, it can also be used as a beautifying feature. This “how-to” will be on Natural stone retaining walls. 1. Identify the site and choose the type of materials. Different types of material can be used to make a retaining wall; this includes natural stone, wood, bricks & mock stone bricks. Follow the steps below to prep the site and construct the retaining wall of your choice. 2. List the building materials and how much you will need. Example (we will use a 5”-12” Building Stone in our example) : a. Base material (3/4” crushed rock): The base should be 20% wider than the length of the wall and width of the wall (generally figured by rock size)…. Example: a 12” rock has a width of 12”. We are building our wall 40 feet long. So, we figure 40’x1’= 40 sq ft. We want our base to be 20% larger so take 40x20% = 8… 40+8= 48. 48 sqft is the area we want to figure for the base of our wall. Now we need to figure how much ¾” crushed stone we will need for this area. We are going to put our crushed stone down 2” deep. So we take 48 and divide it by 162; 48/162=.30 yards.
    [Show full text]
  • DNR Shoreline Alterations – Riprap
    Shoreline Alterations: Riprap What can I do to keep my shoreline from washing away? If your shoreline is eroding, any of the following events may be destabiliz- ing your soil, resulting in erosion: fluctuating water levels, increased wave or wake action, ice pushes, loss of natural vegetation, and human activity. Protecting your shoreline from erosion may not require you to replace natural shoreline with a high-cost, highly engineered retaining wall or IS AN INDIVIDUAL PERMIT riprap. There are affordable, low-impact methods to stabilize your shore- REQUIRED? line and still protect property values, water For most projects constructed below the quality, and habitat. The ordinary high-water level* (OHWL) of Minnesota Department public waters, an individual Public Waters of Natural Resources Work Permit is required by the Minnesota (DNR) encourages you Department of Natural Resources (DNR) . to consider planting native vegetation to Riprap exception: An individual permit control shoreline from the DNR is not required for riprap erosion, enhance placement if the conditions outlined in this aesthetic values, and information sheet are followed. contribute to better water quality in your lake (see Lakescaping information sheet). Both riprap and retain- ing walls can reduce erosion, but they can be expensive and negative- ly affect lakes by creating a barrier Shoreline cross section. between upland areas and the shoreline If you have questions concerning the environment. Riprap Shoreline stabilized with riprap and enhanced contents of this information sheet, contact should only be used with a vegetative buffer. your local DNR Area Hydrologist. See where necessary and contact information on reverse side.
    [Show full text]
  • Sample Plan RETAINING WALL PLANS and PROFILES
    General Information (cont'd): Sample Plan If Noise Walls are to be located on top of retaining walls, contact the Bridge Office 5 1 / for structural recommendations. 8 1 / 8 0 RETAINING WALL PLANS AND PROFILES --------- NARRATIVE Compute all quantities (reinforcement and concrete for stem, footing, parapet or railing, etc.) using the charts in the Standard Plans Manual. Wall quantities should be tabulated. E T A References: Determine the need for traffic barrier, fence, light standards, sign bridges,parapet or railing D Design Scene: Chapter 11 - Walls and/or moment slabs. N O I Determine the need for ditches and drop inlets behind the wall. Coordinate with Water Resources. S I Road Design Manual: Chapter 9-4 V E Determine the need for end protection (plate beam guardrail or impact attenuator). R Standard Plans: 5-297.620 - Retaining Wall General Notes and Summary of Quantities 5-297.621 - Retaining Wall Reinforcement Details (Short Walls) Provide a general note indicating the basic wall design parameters. 5-297.622 - Retaining Wall Reinforcement (Medium Walls) 5-297.623 - Retaining Wall Reinforcement (Tall Walls) Coordinate the location, rustication, top of wall, footings etc. with the Bridge Office when tying into adjacent bridge abutments and wingwalls. Submit Wall Plans and Details to the Bridge Designer prior 5-297.624 - Retaining Wall Miscellaneous Details (6 Sheets) to plan submittal. 5-297.625 - Retaining Wall Shear Lug Details 5-297.626 - Retaining Wall Panel Tabulations (Level Fill)(4 Sheets) Footnotes should be provided for the basis of computation of rebar quantities. For example, "All 5-297.627 - Retaining Wall Panel Tabulations (1V:2H Sloped Fill)(3 Sheets) reinforcement bar quantities were computed using the taller stem height of the 30.5 lin.
    [Show full text]
  • International Society for Soil Mechanics and Geotechnical Engineering
    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. Numerical modelling of groundwater flow around contiguous pile retaining walls Modélisation numérique des écoulements des eaux souterraines autour d’écrans de soutènement de pieux contigusë Wiggan C. A., Richards D.J., Powrie W. University of Southampton, Southampton SO17 1BJ, United Kingdom ABSTRACT: Pore water pressure constitutes a significant proportion of the lateral load acting on a retaining wall. Consequently, guidelines often mandate that the worst case hydraulic conditions are applied in the design of retaining walls. This invariably dictates that retaining walls are treated as impermeable unless special consideration is given to the maintenance of drainage systems or to the prevention of infiltration. Contiguous pile retaining walls are, however, by their nature permeable unless considerable effort is expended to prevent seepage through gaps. If allowed, this seepage can result in reduced active side pore water pressures. Numerical simulations were conducted to determine the impact on pore water pressures of varying the pile gap (x) to diameter (d) ratio, x/d, in a contiguous pile retaining wall. A relationship between x/d and the effective bulk wall permeability, kp was derived, and applied to two-dimensional simulations representing a contiguous pile wall. The results show that pore pressures behind the retaining wall reduced significantly with increased x/d.
    [Show full text]
  • Designing Strong Walls on Weak Soils
    RETAINING WALLS Designing strong walls on weak soils Civil engineers have options to remedy foundation soil problems and meet project cost and schedule requirements. By Fadi Faraj, P.E.; Michael H. Garrison, P.E.; and Brendan FitzPatrick, P.E. he demand for new roadway stabilized earth (MSE) walls. While foundation soil problems include mas- construction or expansion both systems are commonly used, many sive overexcavation and replacement, of existing infrastructure for public and private owners have adopted deep foundations, or staged construc- both public and private own- MSE wall solutions, which represent a tion. Each of these options provides Ters continues to grow. These projects more economical and faster wall con- distinct advantages and disadvantages commonly involve grade-separation struction approach than cast-in-place and is selected based on the project- construction and projects are often cantilevered retaining walls. MSE walls specific needs. restricted by tight schedules, limited can also be designed to tolerate more For instance, overexcavation is most funding, public opposition, and right- settlement. commonly used when the depth of of-way limitations, among other things. However, weak or compressible weak or compressible soils is relatively Although project challenges may vary, foundation soils present significant shallow (less than 10 feet). Removal of one universal question remains for design and construction challenges. shallow, unsuitable soils and replace- engineers, contractors, and owners on Wall heights commonly range from 10 ment with compacted, engineered every project: How do you design and to 40 feet and apply pressures ranging fill is often an inexpensive approach build the project to meet the owner’s from 4,000 to 7,000 pounds per square to provide improved foundation soils cost and schedule requirements? foot (psf) near the wall face, depending in these conditions.
    [Show full text]