Laboratory Testing, Field Investigations and Soil Classification

We have extensive resources on this subject. Below are general works on laboratory and field testing. In addition to these we have special pages with the following:

Assuring Quality in Geotechnical Reporting Documents

Jim Sheahan, P.E., Aaron Zdinak, P.E., and Jerry DiMaggio, P.E.
August 2016

This document presents information intended to assist users with effectively incorporating Quality Assurance (QA) into the preparation of Geotechnical Reporting Documents (GRDs), which includes reports and other documents that communicate geotechnical data, analysis and recommendations. This document draws extensively from Department of Transportation (DOT) experience across the United States. Interviews from several state DOTs were used as a basis for developing QA guidance and applying it to alternative contracting methods (ACM). This manual discusses the distinction between Quality Control (QC) and QA, and guidance is provided on the interactive process they play in the development of GRDs. The use of checklists and QA documentation is discussed in this document, and FHWA-ED-88-053 is referenced as a basis for developing agency/owner specific checklists.

Earth Manual

U.S. Department of Interior, Bureau of Reclamation
Part I, Third Edition

The manual provides current technical information on the field and laboratory investigations and construction control of soils used as foundations and materials for dams, canals, and many other types of structures built for Reclamation projects in the United States of America. It contains both standardized procedures that have been found desirable for securing uniform results throughout the Bureau, and general guidelines intended to assist but not to substitute for engineering judgement.

  • Chapter I describes the Unified Soil Classification System developed jointly by the Bureau of Reclamation and the Corps of Engineers, Department of the Army, from the system proposed by Professor A. Casagrande of Harvard University, and discusses the various properties of soils relating to engineering uses.
  • Investigations of soils are covered in chapter II which describes the various stages of investigation corresponding to the stages of development of the Bureau projects, and gives technical information necessary for planning and executing explorations and for presenting the results.
  • Chapter III presents information on the control of construction from the soils standpoint, for both foundation treatment and compaction control of fills. In addition to a general treatment of the subject applicable to all types of earthwork, separate sections are devoted to problems of rolled earth dams, canals, and miscellaneous construction features. For each of these, information on design features and usual specifications provisions are given to provide control personnel with a background to assist in implementing the recommended control techniques.

The appendix contains detailed procedures for sampling, classification, and field and laboratory testing of soils. Instructions for installing and obtaining information from instruments that measure pore-water pressures and displacements within and adjacent to earth embankments are also included. A tabulation of conversion factors commonly used in earth construction is included at the end of the appendix.

Geotechnical Investigations

USACOE EM 1110-1-1084
1 January 2001


  • EM 1110-1-1804, Geotechnical Investigations, 29 February 1984
  • EM 1110-1-1906, Soil Sampling, 30 September 1996 (this manual includes a copy of that one)

This manual establishes criteria and presents guidance for geotechnical investigations during the various stages of development for civil and military projects. The manual is intended to be a guide for planning and conducting geotechnical investigations and not a textbook on engineering geology and soils exploration. Actual investigations, in all instances, must be tailored to the individual projects.

Geotechnical investigations are performed to evaluate those geologic, seismologic, and soils conditions that affect the safety, cost effectiveness, design, and execution of a proposed engineering project. Insufficient geotechnical investigations, faulty interpretation of results, or failure to portray results in a clearly understandable manner may contribute to inappropriate designs, delays in construction schedules, costly construction modifications, use of substandard borrow material, environmental damage to the site, post-construction remedial work, and even failure of a structure and subsequent litigation. Investigations performed to determine the geologic setting of the project include: the geologic, seismologic, and soil conditions that influence selection of the project site; the characteristics of the foundation soils and rocks; geotechnical conditions which influence project safety, design, and construction; critical geomorphic processes; and sources of construction materials.

Geotechnical Site Characterization

J. Erik Loehr, Ph.D., P.E., Alan Lutenegger, Ph.D., P.E., Brent Rosenblad, Ph.D., P.E., and Andrew Boeckmann, P.E.
FHWA NHI-16-072
November 2016

We also feature this document’s predecessor, Evaluation of Soil and Rock Properties, FHWA-IF-02-034, April 2002

To order Geotechnical Site Characterization in print, click on the image above.

Characterization of subsurface conditions is one of the most challenging yet important activities required for successful planning, design, construction, and operation of transportation infrastructure. This manual is intended to provide a technical resource for geotechnical and highway engineers responsible for planning and performing subsurface investigations so that project subsurface conditions can be characterized effectively and risks attributed to ground conditions can be identified and addressed. The manual is organized to reflect the strong emphasis on interpretation of geotechnical parameters for design and construction. It describes important considerations for planning and scoping of geotechnical investigations; means and methods for classification of soil and rock based on index property measurements; identifying and characterizing potentially problematic soil and rock types for design and construction; guidance for interpretation of soil and rock properties from field and laboratory measurements; interpretation of geotechnical design parameters from collections of individual measurements; identification and characterization of geotechnical hazards; and lastly, guidance for documenting and reporting results from geotechnical investigations.

Soil Mechanics Level I: Unified Soil Classification System

Soil Conservation Service

A training module for the Unified System of soil classification. Includes several lessons and an extensive glossary.

Statistical Analysis of Geotechnical Data

Gregory B. Baecher
U.S. Army Engineer Waterways Experiment Station
Report GL-87-1
September 1987

Traditionally, the planning of qeotechnical site characterization and the analysis of data which result have been accomplished by ad hoc procedures. These rest primarily on intuition and visual inspection of data. Advances in geotechnical testing and modeling combined with stricter regulatory oversight have led to changes with important implications for site characterization and data analysis. Principal among these are: (a) increased numbers and quality of geotechnical data, (b) increased concern with quality assurance in engineering, and (c) increased regulatory interest in the connection between performance assessments, parameter estimates, and supporting data.

At the same time, growing experience with the use of simple statistical methods in geotechnical engineering has provided techniques tailored to the special needs of geotechnical practice. These methods provide means for accommodating recent changes, and for improving the practice of geotechnical engineering. Such statistical methods are well suited to automatic data processing; they provide an explicit, repeatable procedure for obtaining parameter values; and they allow quantified levels of confidence to be assigned to parameter estimates.

The purpose of this report is provide potential users of statistical methods for geotechnical data analysis with an introduction to practical concepts, definitions, and techniques. The report is not exhaustive; it intends to present simple, useful techniques in sufficient detail that a reader not already conversant with statistical theory may undertake practical analyses of geotechnical data. These analyses should make better, more powerful use of data than has been possible with ad hoc procedures, and should provide estimates of uncertainty in engineering parameters to serve as the basis for error analysis of engineering calculations.

USCS and the USDA Soil Classification System: Development of a Mapping Scheme

Rubén A. García-Gaines and Susan Frankenstein
U.S. Army Corps of Engineers, Engineer Research and Development Center
March 2015

The U.S. Department of Agriculture (USDA) soil classification system is relatively simple to apply while the Unified Soil Classification System (USCS) is more complex. As a result, the USDA system, or a similar method, is more commonly used. However, unless taking direct measurements, the USCS classification is needed to determine soil strength. There is no direct relationship between these soil classification systems, and moving from one scheme to another can be tedious and is inexact. Currently, individual researchers, engineers, and soil scientists have their own mapping to move from one system to another, which can lead to confusion when sharing work with others. A consensus method for mapping from one classification scheme to another would avoid this. By analyzing the mappings from six data sets containing thousands of samples, we form such a consensus.