Retaining Walls

Because of the wide variety of topics relating to retaining walls, there are several pages and topics. This page has more general documents; more specific topics are covered in the following pages:

Backfill for Subsurface Structures

UFC 3-220-04FA
16 January 2004

U.S. Army TM 5-818-4, June 1983 (also available)

This manual is for the guidance of designers, specification writers, and especially field personnel engaged in designing, planning, and conducting earthwork operations around major deep-seated or subsurface structures.

The greatest deficiencies in earthwork operations around deep-seated or subsurface structures occur because of improper backfilling procedures and inadequate construction control during this phase of the work. Therefore, primary emphasis in this manual is on backfilling procedures. Design and planning considerations, evaluation and selection of materials, and other phases of earthwork construction are discussed where pertinent to successful backfill operations.

Although the information in this manual is primarily applicable to backfilling around large and important deep-seated or buried structures, it is also applicable in varying degrees to backfilling operations around all structures, including conduits.

Development of an Earth Pressure Model for Design of Earth Retaining Structures in Piedmont Soil

J. B. Anderson and V. O. Ogunro
University of North Carolina at Charlotte College of Engineering
October 2008

Abstract Anecdotal evidence suggests that earth pressure in Piedmont residual soils is typically over estimated. Such estimates of earth pressure impact the design of earth retaining structures used on highway projects. Thus, the development of an appropriate model for estimating earth pressure would result in more rational design of retaining structures in Piedmont residual soils. Accordingly, the objective of this research was to develop an earth pressure model for Piedmont residual soil. An experimental program to estimate, model, and measure earth pressure in Piedmont residual soils was carried out by the University of North Carolina at Charlotte. This study centred around the instrumentation, construction, and load testing of four sheet pile retaining walls at two sites in the Charlotte Belt and Carolina Slate belt regions of the Piedmont. The scope of work included extensive in situ and laboratory soil testing to estimate soil strength parameters for the residual soils; and numerical models to plan the load testing program and evaluate the results. Results of the load tests showed little or no earth pressure due to Piedmont residual soil. Interpretation of data from the sites using theoretical and numerical methods supports this findings. Conclusions from this study include:

  1. The earth pressure currently used in design of retaining structures in Piedmont soils is greater than earth pressure measured during load tests. Field measurements from the instrumented wall load tests demonstrated that the retained soils exerted little or no pressure on the structure.
  2. The Piedmont soils that were tested in this research had significant strength. The average drained friction angle was 28o and the average drained cohesion intercept was above 300 psf. These values were consistent with those found in the literature for similar soils.
  3. Based on the soil test results as well as the minimal earth pressure detected during the load tests, the soil strength parameters, φ’and c’ should be used together in Rankine’s earth pressure equation to predict the earth pressure in Piedmont soils.
  4. Triaxial tests provided the most consistent measurement of φ’ and c’. The borehole shear tests also measure φ and c’ but should only be used when triaxial testing is unavailable.

Geosynthetic Design and Construction Guidelines

Robert D. Holtz, Ph.D., P.E., Barry R. Christopher, Ph.D., P.E., and Ryan R. Berg, P.E.
FHWA HI-95-038
April 1998

This manual is an updated version of the Geotextile Design & Construction Guidelines, used for the FHWA training course Geosynthetic Engineering Workshop. The update was performed to reflect current practices and codes for geotextile design, and has been expanded to address geogrid and geomembrane materials. The manual was prepared to enable the Highway Engineer to correctly identify and evaluate potential applications of geosynthetics as an alternative to other construction methods and as a means to solve construction problems. With the aid of this text, the Highway Engineer should be able to properly design, select, test, specify, and construct with geotextiles, geocomposite drains, geogrids and related materials in drainage, sediment control, erosion control, roadway, and embankment on soft soils applications. Steepened slope and retaining wall applications also are addressed, but designers are referred to the FHWA Demonstration Project No. 82 references on mechanically stabilized earth structures for details on design. Application of geomembranes and other barrier materials to highway works are summarized within. This manual is directed toward geotechnical, hydraulic, roadway, bridge and structures, and route layout highway engineers.

Geosynthetic Reinforced Soil Integrated Bridge System, Interim Implementation Guide

Michael Adams, Jennifer Nicks, Tom Stabile, Jonathan Wu, Warren Schlatter, and Joseph Hartmann

June 2012

This manual outlines the state-of-the-art and recommended practice for designing and constructing Geosynthetic Reinforced Soil (GRS) technology for the application of the Integrated Bridge System (IBS). The procedures presented in this manual are based on 40 years of State and Federal research focused on GRS technology as applied to abutments and walls. This manual was developed to serve as the first in a two-part series aimed at providing engineers with the necessary background knowledge of GRS technology and its fundamental characteristics as an alternative to other construction methods. The manual presents step-by-step guidance on the design of GRS-IBS. Analytical and empirical design methodologies in both the Allowable Stress Design (ASD) and Load and Resistance Factor Design (LRFD) formats are provided. Material specifications for standard GRS-IBS are also provided. Detailed construction guidance is presented along with methods for the inspection, performance monitoring, maintenance, and repair of GRS-IBS. Quality assurance and quality control procedures are also covered in this manual.

Geosynthetic Reinforced Soil Integrated Bridge System, Synthesis Report

Michael Adams, Jennifer Nicks, Tom Stabile, Jonathan Wu, Warren Schlatter, and Joseph Hartmann

January 2011

This report is the second in a two-part series to provide engineers with the necessary background knowledge of Geosynthetic Reinforced Soil (GRS) technology and its fundamental characteristics as an alternative to other construction methods. It supplements the interim implementation manual (FHWA-HRT-11-026), which outlines the design and construction of the GRS Integrated Bridge System (IBS). The research behind the proposed design method is presented along with case histories to show the performance of in-service GRS-IBS and GRS walls.

Relationships between Basic Soils-Engineering Equations and Basic Ground-Water Flow Equations

Donald G. Jorgensen
U.S. Department of the Interior
Geological Survey Water-Supply Paper 2064

The many varied though related terms developed by ground-water hydrologists and by soils engineers are useful to each discipline, but their differences in terminology hinder the use of related information in interdisciplinary studies. Equations for the Terzaghi theory of consolidation and equations for ground-water flow are identical under specific conditions. A combination of the two sets of equations relates porosity to void ratio and relates the modulus of elasticity to the coefficient of compressibility, coefficient of volume compressibility, compression index, coefficient of consolidation, specific storage, and ultimate compaction. Also, transient ground-water flow is related to coefficient of consolidation, rate of soil compaction, and hydraulic conductivity. Examples show that soils engineering data and concepts are useful to solution of problems in ground-water hydrology.

Rockery Design And Construction Guidelines

Darren A. Mack, P.E., Steven H. Sanders, P.E., William L. Millhone, P.E., Renée L. Fippin, P.E., and Drew G. Kennedy, P.G.

November 2006

Rockeries consist of earth retaining and/or protection structures comprised of interlocking, dry-stacked rocks without mortar or steel reinforcement. They have been used for thousands of years and rely on the weight, size, and shape of individual rocks to provide overall stability. Some of the earliest rockeries constructed by the Federal Government date back to 1918. Within the private sector, commercially built rockeries have been constructed in the Pacific Northwest for at least the last four decades and in Northern California and Nevada for at least the last 10 years. As rockery design procedures tend to vary regionally, studies were performed to determine the methods by which rockeries are designed and constructed in various regions throughout the western United States. These design methods were then compared using several typical rockery design loading conditions to determine how the resulting rockery designs differ and which methods are most appropriate for a proposed design for the FHWA’s FLH Divisions. Based on the research performed, a rational design methodology, which evaluates rockery stability as a function of the rockery geometry (height, base width, and batter), rock properties and placement, and lateral pressure imposed by the backfill materials, was developed. A sample design problem is included. Recommendations for specifying and constructing rockeries that are consistent with the design methodology are also provided.

Seismic Structural Considerations for the Stem and Base of Retaining Walls Subjected to Earthquake Ground Motions

Ralph W. Strom and Robert M. Ebeling

U.S. Army Corps of Engineers ERDC/ITL TR-05-3
May 2005

Cantilever retaining walls can respond externally to earthquake ground motions by sliding or by rotating, or internally by stem wall yielding. The type of response that will have the greatest impact on post-earthquake performance will likely depend on restraint conditions at the base of the wall. Walls founded on soil without an invert slab are most likely to dissipate the inertial energy imposed by earthquake ground motions by sliding. This may also be true for walls founded on fissured or fractured rock. Walls founded on soil or on fissured or fractured rock and prevented by an invert slab from moving laterally are more likely to tip (i.e., rotate) than to slide during a major earthquake event. Walls founded on competent rock without significant joints, faults, or bedding planes and prevented by a strong bond at the rock-footing interface from either translating or rotating are likely to dissipate energy through plastic yielding in the stem wall. All three responses can leave the retaining wall in a permanently displaced condition.

The purpose of this report is to provide methodologies for conducting a performance-based earthquake evaluation related to plastic yielding in the stem wall. The methodologies include evaluation of brittle or force-controlled actions and the evaluation of ductile or deformation-controlled actions. The later evaluation provides estimates of permanent (residual) displacement for walls dominated by a stem wall yielding response.

Performance-based evaluation methodologies are demonstrated with respect to a wall designed to current Corps ultimate strength design criteria and with respect to an older retaining wall designed to working stress design criteria. Lap splice deficiencies related to older walls are discussed and performance-based evaluation techniques proposed. At present the Corps computer program CWRotate is able to estimate permanent displacements associated with a sliding response and a rotational response. An enhancement is proposed to provide estimates of permanent (residual) displacement for walls dominated by stem wall yielding.

Trenching and Shoring Manual

California Department of Transportation
Revision 12, January 2000

The engineering objective of a shoring systems is to be both safe and practical. There are two major parts of the engineering effort. First is the classification of the soil to be supported, determination of strength, calculation of lateral loads, and distribution of lateral pressures. This is the soil mechanics or geotechnical engineering effort. Second is the structural design or analysis of members comprising the shoring system. The first part, the practical application of soil mechanics, is the more difficult. The behaviour and interaction of soils with earth support systems is a complex and often controversial subject. “Experts”, books, and papers do not always concur even on basic theory or assumptions. Consequently, there are no absolute answers or exact numerical solutions. A flexible, yet conservative approach, is justified. This manual presents a procedure that will be adequate for most situations.

A portion of the text is devoted to the legal requirements and the responsibilities of the various parties involved. Construction personnel must be aware of the various legal requirements. Special restrictions are noted for excavations or trenches adjacent to railroads. A discussion on manufactured products is included.