Engineering Geology in Washington, Volume 1
Washington Division of Geology and Earth Resources Bulletin 78, 1989
Geotechnical
Properties of Geologic Materials
by
JON
W. KOLOSKI, GeoEngineers, Inc.
SIGMUND D. SCHWARZ, S D
Schwarz and Associates
DONALD W. TUBBS, Tubbs Geosciences
INTRODUCTION
Engineering geologists and geotechnical engineers are an intregal part of the design team for virtually all modern engineering projects that involve site characterization and geotechnical design. Evaluation of alternative project sites or specific site selection usually requires data collection, analysis and explanation of physical site conditions to other members of a project design team. Because of the need to develop a mutual understanding of geologic conditions and the resulting implications for design criteria, a common understanding of the relationship between geologic origin and geotechnical properties is essential. It is imperative that the geologist and engineer work in close cooperation to assure the best product quality.
Traditionally, the geologist's role has focused on identification of the geologic origin and distribution of earth materials. This includes both physical classification and interpretation of the processes of emplacement and modification. The product of a geologist's work within a project design team is often primarily qualitative, usually a map with appropriate descriptions. Such data must be translated into a quantitative form usable in engineering analysis and in design development and evaluation. The translation and quantification of geologic data for engineering purposes occurs over a wide range of scales. Discussion of the distribution of geologic materials and processes commonly involves a megascopic scale of feet or miles, while many engineering properties are discussed in microscopic context. A mutual understanding of terms, units and properties is essential for geologists and engineers to communicate effectively.
This paper relates the geologic characteristics and origin of earth materials commonly found in Washington to certain geotechnical properties. Four tables are presented in which descriptive and interpretive properties of soil and rock materials are correlated with their genetic classification.
The information presented in the tables is useful to indicate the general range of values for typical geotechnical properties, but is no substitute for site-specific laboratory and field information. The tables will be of some direct benefit to students and to geotechnical professionals who are new to the Pacific Northwest; among those with local experience they will serve mainly as a basis for ongoing argument.
The properties indicated in the tables are those most relevant to geotechnical considerations. The values presented in the tables are based on a compilation of published and unpublished information and do not represent original research. These data have been compiled from field and laboratory tests performed over many years by engineers, geologists and geophysicists in both the government and private sectors.
Because of the extremely variable nature of geologic materials, the ranges presented in the tables should be considered representative, but not necessarily all inclusive. Where ranges are indicated, we estimate that roughly two-thirds of field or laboratory observations will fall within the indicated ranges. Some geologic categories are not described in the tables; for example, the tables include no discussion of fill materials or landslide deposits because it is the writers' opinion that these materials are too variable to be meaningfully included. Not all pertinent geotechnical properties are listed and some engineering projects will require information on properties not included in the tables. The design team collectively must evaluate what geological conditions might affect, or be affected by, the engineering project.
DESCRIPTION OF TABLES
The four tables include summaries of descriptive and interpretive properties of soil and rock. The vertical organization of the tables is based on the genetic classification of the materials; descriptive and interpretive properties of general interest for engineering considerations are presented in the horizontal headings. Unified Soil Classification System (USCS) symbols are shown for soil materials and Unified Rock Classification System (URCS) symbols are indicated for rock materials. These classification systems are summarized in Figures 1 and 2. A generalized explanation of terms is presented below, but is not intended to rigorously define either the geologic categories or the geotechnical properties.
Table 1. Descriptive properties of soil; see Table 5 for classification
|
Classification |
Grain |
Sorting |
Dry |
Friction |
Cohesion |
Permeability |
Storage |
Seismic |
Resistivity |
|
|
Geologic |
USCS |
Size |
|
Density |
angle |
|
|
capacity |
velocity |
|
|
|
|
|
|
(pcf) |
(deg) |
(psf) |
(fpm) |
|
(fps x 1000) |
(ohm-m x 1000) |
|
ALLUVIAL |
|
|
|
|
|
|
|
|
|
|
|
High Energy |
GW,GP, GM |
Med- Coarse |
Med- Good |
115-130 |
30-35 |
0 |
0.01-10 |
0.1-0.3 |
1.5-5dry 5-7.5wet |
0.3-30dry 0.2-20wet |
|
Low Energy |
ML,SM, SP,SW |
Fine-Med |
Med- Good |
90-115 |
15-30 |
0-500 |
0.0001-0.1 |
0.05-0.2 |
1-4dry 3.5-6wet |
0.01-10dry 0.001-1wet |
|
COLLUVIAL |
. . . . . . . . . . . . . . . . . . . . Variable . . . . . . . . . . . . . . . . . . . Reflects parent material . . . . . . . . . . . . . . . . |
|||||||||
|
EOLIAN |
|
|
|
|
|
|
|
|
|
|
|
Dune Sand |
SP |
Medium |
Very Good |
90-110 |
30-35 |
0 |
0.01-0.1 |
0.1-0.3 |
1-2.5 |
0.5-100 |
|
Loess |
ML, SM |
Fine |
Med-Good |
80-100 |
20-30 |
500-1000 |
0.001-0.01 |
0.05-0.1 |
0.75-2.5 |
0.01-2 |
|
GLACIAL |
|
|
|
|
|
|
|
|
|
|
|
Till |
SM, ML |
Fine-Med |
Poor |
120-140 |
35-45 |
1000-4000 |
0-0.001 |
0-0.01 |
3.5-10 |
0.01-5 |
|
Outwash |
GW,GP, SW,SP, SM |
Med- Coarse |
Poor- Good |
115-130 |
30-40 |
0-1000 |
0.01-10 |
0.01-0.3 |
4-6dry 5-8.5wet |
0.2-10dry 0.1-5wet |
|
Glaciolacustrine |
ML, SM,SP |
Fine-Med |
Good |
100-120 |
15-35 |
0-3000 |
0-0.1 |
0-0.1 |
2.5-8.5 |
0.001-2 |
|
LACUSTRINE |
|
|
|
|
|
|
|
|
|
|
|
Inorganic |
ML,SM, MH |
Fine |
Good |
70-100 |
5-20 |
0-200 |
0.0001-0.1 |
0.05-0.3 |
1-2.5 |
0.001-0.5 |
|
Organic |
OL, PT |
Fine-Med |
Poor- Good |
10-70 |
0-10 |
0-200 |
0.0001-1.0 |
0.05-0.8 |
0.5-1.5 |
0.001-0.5 |
|
MARINE |
|
|
|
|
|
|
|
|
|
|
|
High Energy |
SW,GW, SP |
Med- Coarse |
Med- Good |
115-130 |
25-35 |
0 |
0.001-1.0 |
0.1-0.3 |
5-6 |
0-2 |
|
Low Energy |
ML,SM, MH |
Fine-Med |
Med- Good |
70-115 |
0-25 |
0-200 |
0.0001-0.1 |
0.05-0.3 |
2.5-5 |
0-0.5 |
|
RESIDUAL |
. . . . . . . . . . . . . . . . . . . . Variable . . . . . . . . . . . . . . . . . . . Reflects parent material . . . . . . . . . . . . . . . . |
|||||||||
|
VOLCANIC |
|
|
|
|
|
|
|
|
|
|
|
Tephra |
ML,SM |
Fine-Med |
Poor- Good |
80-120 |
20-35 |
0-1000 |
0.0001-0.1 |
0.05-0.2 |
0.5-6 |
0.5-100 |
|
Lahar |
SM,SW, GM |
Fine- Coarse |
Poor |
80-130 |
25-40 |
0-1000 |
0.001-0.1 |
0.05-0.2 |
3.5-9 |
0.01-5 |
Table 2. Interpretive properties of soil; see Table 5 for classification
|
Classification |
Relative |
Excavation |
Moisture |
Foundation |
Cut |
Seismic |
Common |
|
|
Geologic |
USCS |
erodibility |
difficulty |
sensitivity |
support |
slopes |
hazards |
uses |
|
|
|
|
|
|
(psf) |
(%) |
|
|
|
ALLUVIAL |
|
|
|
|
|
|
|
|
|
High Energy |
GW,GP, GM |
Low |
Low |
Low |
1500-2000 |
50-65 |
Low-Med |
Aggregate, Fill |
|
Low Energy |
ML,SM, SP,SW |
Med-High |
Low |
Med-High |
500-1500 |
25-50 |
Med-High |
Fill |
|
COLLUVIAL |
. . . . . . . . . . . . . . . . . . . . Variable . . . . . . . . . . . . . . . . . . . Reflects parent material . . . . . . . . . . . . |
|||||||
|
EOLIAN |
|
|
|
|
|
|
|
|
|
Dune Sand |
SP |
High |
Low |
Low |
500-1000 |
20-30 |
Low-Med |
Fill, Industrial |
|
Loess |
ML,SM |
Very High |
Low |
High |
500-1000 |
25-50 |
Low-Med |
|
|
GLACIAL |
|
|
|
|
|
|
|
|
|
Till |
SM,ML |
Low-Med |
Med-High |
High |
1500-5000 |
50-100 |
Low |
Fill |
|
Outwash |
GW,GP, SW,SP, SM |
Low-Med |
Low-Med |
Low-Med |
1500-3000 |
50-70 |
Low |
Aggregate, Fill |
|
Glaciolacustrine |
ML,SM, SP |
Med-High |
Medium |
High |
1000-2000 |
25-50 |
Med-High |
Fill, Industrial |
|
LACUSTRINE |
ML,SM, MH,OL, PT |
High |
Low |
High |
0-500 |
0-25 |
High |
PT: Soil additive |
|
MARINE |
|
|
|
|
|
|
|
|
|
High Energy |
SW,GW, SP |
Medium |
Low |
Low |
1000-2000 |
25-60 |
Low-Med |
Fill |
|
Low Energy |
ML,SM, MH |
High |
Low |
Med-High |
0-500 |
0-25 |
High |
Fill |
|
RESIDUAL |
. . . . . . . . . . . . . . . . . . . . Variable . . . . . . . . . . . . . . . . . . . Reflects parent material . . . . . . . . . . . . |
|||||||
|
VOLCANIC |
|
|
|
|
|
|
|
|
|
Tephra |
ML,SM |
Low-High |
Low |
Low-High |
500-1500 |
20-50 |
Low-Med |
Fill, Industrial |
|
Lahar |
SM,GM |
Med-High |
Low-Med |
Low-High |
500-1500 |
25-50 |
Low-Med |
Fill |
Table 3. Descriptive properties of rock; see Table 6 for classification
|
Classification |
Density |
Compressive |
Discontinuities |
Permeability |
Storage |
Seismic |
Resistivity |
|
|
Geologic |
URCS |
strength |
|
|
capacity |
velocity |
||
|
|
|
(pcf) |
(psi x 1000) |
|
|
|
(fps x 1000) |
(ohm-m x 1000) |
|
IGNEOUS |
|
|
|
|
|
|
|
|
|
Intrusive |
OAAA - OCEB |
150-200 |
3-30 |
Joints |
Low |
Low |
12-20 |
0.5-20 |
|
Extrusive |
OAAA - ODEE |
120-200 |
1-30 |
Joints, Voids, Flow Features |
Low-High |
Low-High |
6-18 |
0.01-5 |
|
METAMORPHIC |
|
|
|
|
|
|
|
|
|
High Grade |
OAAA - OCED |
150-200 |
3-25 |
Joints, Foliation |
Low |
Low |
12-20 |
0.05-20 |
|
Low Grade |
OBAA - OEEE |
150-200 |
0.5-15 |
Joints, Foliation |
Low |
Low |
2.5-14 |
0.001-10 |
|
SEDIMENTARY |
|
|
|
|
|
|
|
|
|
Clastic |
OBCC - OEEE |
130-150 |
1-15 |
Joints, Bedding |
Low-Med |
Low-Med |
5-14 |
0.001-10 |
|
Chemical |
OBCB - ODEC |
140-160 |
2-15 |
Joints, Bedding, Voids |
Low-High |
Low |
4-15 |
0.05-50 |
|
Organic |
OCCD - ODEE |
80-100 |
0.5-5 |
Joints, Bedding, Voids |
Low-Med |
:Low |
1.5-5.5 |
0.05 1 |
Table 4. Interpretive properties of rock; see Table 6 for classification
|
Classification |
Excavation |
Resistance |
Foundation |
Stability |
Common |
|
|
Geologic |
URCS |
difficulty |
to weathering |
support |
in cuts |
uses |
|
IGNEOUS |
|
|
|
|
|
|
|
Intrusive |
OAAA - OCEB |
High |
High |
Good |
Good |
Riprap, Aggregate, Building stone |
|
Extrusive |
OAAA - ODEE |
Med-High |
Med-High |
Usually Good |
Med-Good |
Riprap, Aggregate, Building stone |
|
METAMORPHIC |
|
|
|
|
|
|
|
High Grade |
OAAA - OCED |
High |
High |
Good |
Good |
Riprap, Aggregate, Building stone, Industrial |
|
Low Grade |
OBAA - OEEE |
Low-High |
Low-Med |
Usually Good |
Poor-Good |
Fill |
|
SEDIMENTARY |
|
|
|
|
|
|
|
Clastic |
OBCC - OEEE |
Low-High |
Low-Med |
Usually Good |
Poor-Good |
Building stone, Industrial |
|
Chemical |
OBCB - ODEC |
Med-High |
Low-High |
Usually Good |
Poor-Good |
Riprap, Aggregate, Industrial, Building stone |
|
Organic |
OCCD - ODEE |
Low-Med |
Low |
Poor |
Poor |
Fuel |
Table 5. Unified Soil Classification System; from American Society for Testing and Materials, 1985
|
MAJOR DIVISIONS |
GROUP SYMBOL |
GROUP NAME |
||
|
COARSE GRAINED SOILS MORE THAN 50% RETAINED ON NO.200 SIEVE |
GRAVEL MORE THAN 50% OF COARSE FRACTION RETAINED ON NO.4 SIEVE |
CLEAN GRAVEL |
GW |
WELL-GRADED GRAVEL, FINE TO COARSE GRAVEL |
|
GP |
POORLY-GRADED GRAVEL |
|||
|
GRAVEL WITH FINES |
GM |
SILTY GRAVEL |
||
|
GC |
CLAYEY GRAVEL |
|||
|
SAND MORE THAN 50% OF COARSE FRACTION PASSES NO.4 SIEVE |
CLEAN SAND |
SW |
WELL-GRADED SAND, FINE TO COARSE SAND |
|
|
SP |
POORLY-GRADED SAND |
|||
|
SAND WITH FINES |
SM |
SILTY SAND |
||
|
SC |
CLAYEY SAND |
|||
|
FINE GRAINED SOILS MORE THAN 50% PASSES NO.200 SIEVE |
SILT AND CLAY LIQUID LIMIT LESS THAN 50 |
INORGANIC |
ML |
SILT |
|
CL |
CLAY |
|||
|
ORGANIC |
OL |
ORGANIC SILT, ORGANIC CLAY |
||
|
SILT AND CLAY LIQUID LIMIT 50 OR MORE |
INORGANIC |
MH |
SILT OF HIGH PLASTICITY, ELASTIC SILT |
|
|
CH |
CLAY OF HIGH PLASTICITY, FAT CLAY |
|||
|
ORGANIC |
OH |
ORGANIC CLAY, ORGANIC SILT |
||
|
HIGHLY ORGANIC SOILS |
PT |
PEAT |
||
Table 6. Unified Rock Classification System, from Williamson, 1984
|
DEGREE OF WEATHERING |
REPRESENTATIVE |
A |
Micro Fresh State (MFS) |
||
|
B |
Visually Fresh State (VFS) |
||||
|
ALTERED |
C |
Stained State (STS) |
|||
|
WEATHERED |
>GRAVEL SIZE |
D |
Partly Decomposed State (PDS) |
||
|
<SAND SIZE |
E |
Completely Decomposed State (CDS) |
|||
|
ESTIMATED STRENGTH |
REACTION TO IMPACT OF 1 LB BALLPEEN HAMMER |
A |
"Rebounds" (Elastic) (RQ) |
>15000 psi (2) |
|
|
B |
"Pits" (Tensional) (PQ) |
8000 - 15000 psi (2) |
|||
|
C |
"Dents" (Compression) (DQ) |
3000 - 8000 psi (2) |
|||
|
D |
"Craters" (Shears) (CQ) |
1000 - 3000 psi (2) |
|||
|
REMOLDING (1) |
E |
"Moldable" (Friable) (MQ) |
<1000 psi (2) |
||
|
DISCONTINUITIES |
VERY LOW PERMEABILITY |
A |
Solid (Random Breakage) (SRB) |
||
|
B |
Solid (Preferred Breakage) (SPB) |
||||
|
C |
Solid (Latant Planes of Separation) (LPS) |
||||
|
MAY TRANSMIT WATER |
D |
Nonintersecting Open Planes (2-D) |
|||
|
E |
Intersecting Open Planes (3-D) |
||||
|
UNIT WEIGHT |
A |
Greater than 160 pcf |
|||
|
B |
150 - 160 pcf |
||||
|
C |
140 - 150 pcf |
||||
|
D |
130 - 140 pcf |
||||
|
E |
Less than 130 pcf |
||||
|
(1) Strength estimated by soil mechanics techniques |
(2) Approximate unconfined compressive strength |
||||
|
SYMBOL NOTATION: AAAA IN ORDER WEATHERING, STRENGTH, DISCONTINUITIES, WEIGHT |
|||||
|
"O" IS USED AS A POSITION HOLDER |
|||||
EXPLANATION OF TERMS
Soils
o Alluvial: Sediment deposited by streams.
- High Energy: Generally coarse sediment such as coarse sand, gravel, cobbles and boulders that have been deposited by fast moving water.
- Low Energy: Generally fine-grained soil such as fine sand and silt deposited by slow moving water.
o Colluvial: Generally heterogeneous soil aggregates that have been transported and deposited by mass wasting processes such as landslides, rockfalls and avalanches.
o Eolian: Sediment transported and deposited by wind.
- Dune Sand: Sand-size sediment; typically deposited in dune forms.
- Loess: Fine-grained sediment; generally fine sand and silt.
o Glacial: Material deposited by or in association with glaciers.
- Till: Heterogeneous mixture of various particle sizes deposited directly by glacial ice.
- Outwash: High-energy sediment deposited by glacial meltwater.
- Glaciolacustrine: Low-energy sediment deposited in ice-marginal lakes.
o Lacustrine: Sediment deposited in lakes.
- Nonorganic: Sediment composed primarily of silt, sand and clay.
- Organic: Peat and other predominantly organic sediment.
o Marine: Sediment deposited in a marine environment.
- High Energy: Generally coarse-grained material such as gravel and sand deposited by strong waves or currents.
- Low Energy: Generally fine-grained material such as silt and sand.
o Residual: Soil developed in place as the result of weathering or chemical decomposition of parent material.
o Volcanic: Deposits derived from volcanoes or other eruptive sources.
- Tephra: Airborne volcanic ejecta such as volcanic bombs, cinders and ash.
- Lahar: Mudflow composed largely of volcanic debris, or having primarily a volcanic origin.
Bedrock
o Igneous: Rock formed by solidification from a molten state.
- Intrusive: Rock such as granite that has solidified from a molten state below the ground surface.
- Extrusive: Rock such as basalt that has solidified after reaching the ground surface.
o Metamorphic: Rock derived from pre-existing rock by mineralogical and textural changes.
- High Grade: Metamorphic rock that has little resemblance to the original parent rock type.
- Low Grade: Metamorphic rock that is similar to the original parent rock type.
o Sedimentary: Rock deposited as sediment and subsequently lithified.
- Clastic: Rock such as shale, sandstone and conglomerate formed from fragments of pre-existing rocks.
- Chemical: Rock such as limestone formed by chemical precipitation.
- Organic: Rock such as coal formed largely or exclusively from organic material.
Descriptive Properties
o USCS: Unified Soil Classification System (ASTM D 2487).
o URCS: Unified Rock Classification System (Williamson, 1984).
o Grain Size: The general category of particle sizes corresponding to terms used in the USCS.
o Sorting: Segregation by grain sizes. "Poor" means a wide range of grain sizes such as silty sandy gravel; "good" means a narrow range of grain sizes such as sand. No specific percentages are implied.
o Dry Density: Dry weight in pounds per cubic foot.
o Friction Angle: Angle of internal shearing resistance (phi) expressed in degrees.
o Cohesion: That part of the shear strength of soil or rock which does not depend on interparticle friction.
o Permeability (Hydraulic Conductivity): The ease with which water will move through soil interstices, expressed in feet per minute. For rock, variability is so great that it is expressed in the tables in dimensionless relative terms only. Negligible permeability is expressed as 0.
o Storage Capacity (Specific Yield): The volume of water that will drain from a unit volume of an unconfined aquifer.
o Seismic Velocity: Compressional seismic wave velocity in thousands of feet per second.
o Resistivity: Electrical resistance to direct current expressed in terms of thousands of ohm-meters.
o Compressive Strength: Load per unit area under which an unconfined block of rock fails (unconfined compressive strength), expressed in pounds per square inch.
o Discontinuities: Surfaces or voids that interrupt otherwise
homogeneous rock masses.
Interpretive Properties
o Relative Erodibility: Susceptibility to erosion in terms of sediment yield per unit area.
o Excavation Difficulty: The relative difficulty of excavation by heavy equipment.
o Moisture Sensitivity: Susceptibility to significant changes in physical properties due to changes in water content. In general, sensitivity increases with increasing silt or clay content.
o Foundation Support: Typical allowable bearing value for shallow spread foundations, expressed in pounds per square foot. Assumes conventional cast-in-place concrete footings with embedment adequate for frost protection. Expressed in dimensionless relative terms only for rock.
o Cut Slopes (Soil): Typical maximum inclination for permanent cut slopes less than 15 feet in height. Assumes no destabilizing factors such as adverse structural/stratigraphic or ground water conditions.
o Stability in Cut Slopes (Rock): Relative stability of permanent cut slopes. Assumes no destabilizing factors such as adverse structural/stratigraphic or ground water conditions.
o Seismic Hazards: Relative association with earthquake-induced damage.
o Common Uses: Typical applications of economic importance.
o Resistance to Weathering: Relative resistance to mechanical or chemical deterioration.
DISCUSSION
Descriptive Properties
o The Unified Soil Classification System (USCS) does not recognize
particles larger than 3 inches in diameter. Common usage extends
it to materials including cobbles (3 to 12 inches) and boulders
(greater than 12 inches).
o Cohesion is the result of soil structure and/or cementation. Some finite cohesion is generally present in loess, due to its unique granular structure and the common occurrence of minor cementation. Cohesion in till is a result of ice consolidation and a wide range of particle sizes, including a significant fraction of silt.
o Permeability differences reflect variations in gradation between geologic materials. Very high permeability is associated with high-energy alluvial deposits or glacial outwash where coarse, open-work gravel is common. Permeability in these deposits can vary greatly over short horizontal and vertical distances. Extremely low permeability is associated with poorly to moderately sorted materials that are ice-consolidated and contain a substantial fraction of silt and clay.
o Storage capacity reflects the volume of void space and the content of silt or clay within a soil deposit. Storage capacity is very small for poorly sorted or ice-consolidated, fine-grained materials such as till and glaciolacustrine deposits.
o Seismic velocities in soil can be affected by water content. Coarse-grained soils display significantly higher velocities when water saturated. Less velocity increase is associated with finer-grained soils. The electrical resistivity of soil and rock decreases with water content. Geophysical values are differentiated between wet and dry conditions where differences are significant and data is available.
Interpretive Properties
o Erodibility is closely related to slope, vegetative cover, water concentration and numerous other factors in addition to geologic characteristics.
o Excavation difficulty is discussed in more detail in handbooks published by Caterpillar, Inc. (1987a, b). Note that the table entries for this category refer to unrestricted excavation. Restricted excavations such as trenches are normally more difficult than open cuts. Substantial variations from the indicated values should be expected based on site-specific factors.
o Satisfactory foundation performance includes consideration of numerous factors in addition to the indicated bearing values. These factors include settlement performance, general stability and effects of and on adjacent manmade or natural features.
o The design of safe cut slopes must consider site-specific details of soil and water conditions and their relationship to risk. For example, a maintenance risk is much less significant than a life-threatening risk. Therefore, rather than relying on physical properties, risk will often dictate slope design.
o Seismic hazards can be manifested in the form of ground shaking, liquefaction, ground rupture or displacement (e.g., landslides induced by seismic shaking). The extent to which the indicated geologic classifications are associated with seismic hazards is expressed in relative terms.
o Moisture sensitivity varies considerably within each geologic classification. For example, low-energy alluvial deposits characterized by clean, free-draining sand are not particularly moisture-sensitive while low-energy alluvial soils containing a substantial fraction of silt are extremely moisture-sensitive. Although not included as a specific interpretive category for rock, moisture sensitivity can also be important. The moisture sensitivity of rock is generally proportional to the amount of clay or silt produced by mechanical or chemical decomposition.
ACKNOWLEDGEMENTS
The writers wish to express appreciation to their colleagues in the geotechnical professions who over the years have shared information regarding geotechnical properties of geologic materials. Several organizations (GeoEngineers, Inc., Geo-Recon International Ltd., Shannon & Wilson, Inc., and the U.S. Army Corps of Engineers) made available to us specific information from their files. GeoEngineers, Inc., also provided assistance in manuscript preparation.
We are particularly grateful to Mr. George Yamane for his helpful review and comments during the preparation of this paper.
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