Bearing Capacity of Soils

Note: this book is available in print. Click here for more information.

Engineer Manual EM 1110-1-1905
30 October 1992

This manual presents guidelines for calculation of the bearing capacity of soil under shallow and deep foundations supporting various types of structures and embankments. This information is generally applicable to foundation investigation and design conducted by Corps of Engineer agencies.

Principles for evaluating bearing capacity presented in this manual are applicable to numerous types of structures such as buildings and houses, towers and storage tanks, fills, embankments and dams. These guidelines may be helpful in determining soils that will lead to bearing capacity failure or excessive settlements for given foundations and loads.

Bearing capacity is the ability of soil to safely carry the pressure placed on the soil from any engineered structure without undergoing a shear failure with accompanying large settlements. Applying a bearing pressure which is safe with respect to failure does not ensure that settlement of the foundation will be within acceptable limits. Therefore, settlement analysis should generally be performed since most structures are sensitive to excessive settlement.

Compaction and Settlement of Existing Embankments

Robert L. Parsons, Ph.D., P.E., Derek H. Foster, and Stephen A. Cross, Ph.D., P.E., University of Kansas
KTRAN: KU-00-8
December 2001

Unanticipated settlement of compacted earth fill has been a continuing problem for embankments managed by KDOT. This report contains the results of an investigation of current compaction specifications, with particular emphasis on the Type B compaction specification that relies on visual verification of compaction by sheepsfoot roller walkout.

This investigation consisted of two parts: a field investigation of existing embankments with varying levels of performance and a telephone survey of other DOT’s to determine the status of compaction specifications. Eight embankments constructed between 1994 and 2000 were selected for undisturbed field sampling. Two borings were drilled in each embankment and shelby tube samples were collected for testing at regular intervals. Samples of the cuttings were also collected for testing.

A telephone survey of all state DOT’s was conducted to assess current practice with regard to specifications for compaction of fills. Thirty-two states, including Kansas, responded to the survey. It was determined that a number of compaction and moisture specifications are currently in use, however there were common themes among the specifications.

Based on the results of this research it is recommended that KDOT specify a relative compaction standard and a moisture content range based on the optimum moisture content for compaction of embankments. It is recommended that the compaction standard be at least 95 percent of maximum density as determined by KT-12 (AASHTO T 99), or an equivalent relative compaction based on modified effort (AASHTO T 180). It is also recommended that the specified moisture range be centered about optimum or a point slightly above optimum, as the average moisture content of the existing embankments is slightly above optimum.

Design and Construction of Shale Embankments: Summary

FHWA-TS-80-219
April 1980

Guidelines for the use of shales in new construction, evaluation of existing embankments, and remedial treatment of distressed shale embankments are briefly described in this summary report.

Construction of the modern highway system has required large , high embankments using economically available fill from adjacent cuts or nearby borrow sources. Because of their widespread occurrence, shales and other weak, fine-grained sedimentary rock (siltstone, claystone, mudstone, etc.) were the main source of fill for many embankments from the Appalachian region to the Pacific Coast.

Dewatering and Groundwater Control

U.S. Army TM 5-815-5
November 1983

This manual provides guidance for the planning, design, supervision, construction, and operation of dewatering and pressure relief systems and of seepage cutoffs for deep excavations for structures. It presents: description of various methods of dewatering and pressure reliefi techniques for determining groundwater conditions, characteristics of pervious aquifers, and dewatering requirements; guidance for specifying requirements for dewatering and seepage control measures; guidance for determining the adequacy of designs and plans prepared by contractors; procedures for designing, installing, operating, and checking the performance of dewatering systems for various types of excavations; and descriptions and design of various types of cutoffs for controlling groundwater.

Earthmoving Operations

U.S. Army FM 5-434
15 June 2000

This field manual (FM) is a guide for engineer personnel responsible for planning, designing, and constructing earthworks in the theater of operations. It gives estimated production rates, characteristics, operation techniques, and soil considerations for earthmoving equipment. This guide should be used to help select the most economical and effective equipment for each individual operation.

This manual discusses the complete process of estimating equipment production rates. However, users of this manual are encouraged to use their experience and data from other projects in estimating production rates. The material in this manual applies to all construction equipment regardless of make or model. The equipment used in this manual are examples only. Information for production calculations should be obtained from the operator and maintenance manuals for the make and model of the equipment being used.

EMBANK: A Microcomputer Program to Determine One-Dimensional Compression Settlement Due to Embankment Loads

The EMBANK computer program itself can be downloaded here.

Dr. Alfredo Urzua
FHWA-SA-92-045
May 1993

The objective of this report is to introduce a microcomputer program for computing one-dimensional compression vertical settlement due to embankment loads. The program follows the equations presented by Lambe & Whitman (1969), Ladd (1973), and Poulos & Davis (1974). For the case of a strip symmetrical vertical embankment loading, the program superimposes two vertical embanknent loads. For the increment of vertical stresses at end of fill, the program internally superimpose a series of 10 rectangular loads to create the end-of-fill condition. The report presents the equations and analytical procedures utilized by the program and examples of the capabilities of the user-friendly data entry form. The computer program is coded in the Turbo Pascal 4.0 language and takes full advantage of the stand-alone, (single-user) characteristics of the IBM-PC through the use of “friendly” input menus and data-checking routines.

The code implements copyrighted portions of the microcomputer programs SAF-I and STRESS developed by PROTOTYPE Engineering, Inc., Winchester, MA, and uses the screen editor Turbo Magic From Sophisticated Software.

An Engineering Manual for Slope Stability Studies

J.M. Duncan, A.L. Buchignani and M. de Wet
Virginia Polytechnic University
March 1987

The purpose of this manual is to provide a simple, practical guide for slope stability studies. It is concerned with (1) the characteristics and critical aspects of various types of slope stability problems, (2) geologic studies and site investigation procedures, (3) methods of designing slopes, including field observations and experience, slope stability charts, and detailed analyses, (4) factors of safety, and (5) methods of stabilizing slopes and slides. The emphasis of this manual is on simple, routine procedures. It does not include advanced analysis procedures, nor does it deal with specialized problems such as design of dams or the stability of slopes during earthquakes. References are given to the sources of the material contained in the manual, and to more advanced procedures where appropriate, to provide avenues for studies going beyond the scope of this manual.

Large-Scale Load Tests and Data Base of Spread Footings on Sand

FHWA-RD-97-068
November 1997

Spread footings are most often less expensive than deep foundations. In an effort to improve the reliability of spread footings, this research project was undertaken. The results consist of

1. A user friendly microcomputer data base of spread footings, case histories and load tests.
2. The performance of five large scale square footings in sand.
3. An evaluation of the current accuracy of settlement and bearing capacity prediction methods.
4. Observations on the scale effect, the zone of influence, the creep settlement, and soil heterogeneity.
5. A new and simple method to predict the complete load settlement curve for a footing as well as several correlations.
6. Evaluation of the WAR test, a dynamic test for spread footings.

Performance of Highway Bridge Abutments Supported by Spread Footings on Compacted Fill

Albert F. Di Millio
FHWA-RD-81-184
October 1982

A visual inspection was made o f the structural condition o f 148 highway bridges supported by spread footings on compacted fill throughout the State of Washington. The approach pavements and other bridge appurtenances were also inspected for damage or distress that could be attributed to the use of spread footings on compacted fill. This review, in conjunction with detailed investigations o f the foundation movement of 28 selected bridges, was used to evaluate the performance of spread footings on compacted fills . It was concluded that spread footings can provide a satisfactory alternative to piles especially when high embankments of good quality borrow materials are constructed over satisfactory foundation soils . None of the bridges investigated displayed any safety problems serious functional distress. All bridges were in good condition and many were found t o be in very good condition. In addition to the performance evaluation, costeffectiveness analyses and tolerable movement correlation studies were made to further substantiate the feasibility of using spread footings in lieu of expensive deep foundation systems. Cost analyses showed spread footings were 50-65 percent cheaper than the alternate choice o f pile foundations. Foundation movement studies showed that these bridges have easily tolerated differential settlements of 1-3 inches (25-75 mm) without serious distress.

Shallow Foundations

FHWA-SA-02-054
September 2002

This document is FHWA’s primary reference of recommended design and procurement procedures for shallow foundations. The Circular presents state-of-the-practice guidance on the design of shallow foundation support of highway bridges. The information is intended to be practical in nature, and to especially encourage the cost-effective use of shallow foundations bearing on structural fills. To the greatest extent possible, the document coalesces the research, development and application of shallow foundation support for transportation structures over the last several decades.

Detailed design examples are provided for shallow foundations in several bridge support applications according to both Service Load Design (Appendix B) and Load and Resistance Factor Design (Appendix C) methodologies. Guidance is also provided for shallow foundation applications for minor structures and buildings associated with transportation projects.

Slope Maintenance and Slide Restoration

Tommy C. Hopkins, David L. Allen, Robert C. Deen and Calvin G. Grayson
FH WA-RT-88-040
December 1988

Each year U.S. highway agencies spend millions of dollars in maintaining highway embankments, slopes, and other earth structures as well as removing rock falls and soil debris from roadways and repairing landslides. Activities from maintaining highway slopes and restoring landslides often cause traffic slow dawn and stoppage that creates serious safety hazards and consumes significant highway maintenance and construction funds. In addition, economic losses due to the inconvenience to the traveling public is often immeasutable.

During 1984 and 1985, as part of a continuing project to evaluate and improve maintenance activities, a study on slope maintenance and slide restoration was undertaken by the Federal Highway Administration (FHWA), Office of Implementation. This joint effort by engineers from the FHWA and six state highway agencies (that is, California, Kentucky, Oregon, Pennsylvania, Texas, and Wyoming) developed guidelines for slope maintenance and slide restoration. These guidelines reflect the collective experience of the six state highway agencies and are documented in FHWA report (TS-85-231) entitled "Guidelines for Slope Maintenance and Slide Restoration."

This technical note was developed and based on the above report for use by Technology Transfer Centers funded through the Rural Technical Assistance Program of the Federal Highway Administration in conducting training of the subject title.

This manual represents one of the many contributions of Dr. Robert C. Deen to the transportation research , and education community. Dr. Deen died on March 25, 1988, while completing the editing of this manual.

Slope Stability

Engineer Manual EM 1110-2-1902
31 October 2003

This engineer manual provides guidlance for analysing the static stability of slopes of earth and rock-fill dams, slopes of other types of embankments, evacuated slopes, and natural slopes in soil and soft rock. Methods for analysis of slope stability are described and are illustraed by examples in the appendices. Criteria are presented for strength tets, analysis conditions, and factors of safety. The criteria in this manual are to be used with methods of stability analysis that satisfy all conditions of equilibrium. Methods that do not satify all conditions of equilibrium may involve significant inaccuracies and should only be used under the restricted conditions described herein.