ASTM D6528-00
(Test Method)Standard Test Method for Consolidated Undrained Direct Simple Shear Testing of Cohesive Soils
Standard Test Method for Consolidated Undrained Direct Simple Shear Testing of Cohesive Soils
SIGNIFICANCE AND USE
The shear strength of a specimen depends on the soil type, normal consolidation stress, time of consolidation, rate of strain, and prior stress history of the soil.
In this test, the shear strength is measured under constant volume conditions that are equivalent to undrained conditions for a saturated specimen; hence, the test is applicable to field conditions wherein soils have fully consolidated under one set of stresses, and then are subjected to changes in stress without time for further drainage to take place.
The constant volume (undrained) strength is a function of stress conditions. In this test method, the strength is measured under plane strain conditions and the principle stresses continuously rotate due to the application of shear stress. This simple shear stress condition occurs in many field situations including zones below a long embankment and around axially loaded piles.
The state of stress within the simple shear specimen is not sufficiently defined nor uniform enough to allow rigorous interpretation of the results. Expressing the data in terms of the shear stress and normal effective stress on the horizontal plane is useful for engineering purposes, but should not be confused with the effective stress parameters derived from other shear tests having better defined states of stress.
The values of the secant shear modulus can be used to estimate the initial settlements of embankments built on saturated cohesive soils due to undrained shear deformations.
The data from the consolidation portion of this test are comparable to results obtained using Test Method D 2435 provided that the more rigorous consolidation procedure of Test Method D 2435 is followed.
5.6.1 The axial displacements measured from Test Method D 2435 are somewhat smaller than for the simple shear test because the specimen’lateral confinement is less rigid and the top platen is unable to rotate.
5.6.2 The estimated preconsolidation pressure is comparable provided the spec...
SCOPE
1.1 This test method defines equipment specifications and testing procedures for the measurement of constant volume strength and stress-strain characteristics of cohesive soils after one-dimensional consolidation using a constant rate of simple shear deformation mode of loading. The constant volume condition is equivalent to the undrained condition for saturated specimens.
1.2 This test method is written specifically for devices that test rectangular parallelepiped or cylindrical specimens. Other more general devices, such as the torsional shear hollow cylinder, may be used to perform consolidated constant volume simple shear tests but are beyond the scope of this test method.
1.3 This test method is applicable to testing both undisturbed and compacted soils, however, it does not include specific guidance for compacting test specimens.
1.4 It shall be the responsibility of the agency requesting this test to specify the magnitude of the normal consolidation stress prior to constant volume shear and, when appropriate, the maximum normal consolidation stress, which will result in an overconsolidated specimen.
1.5 The values stated in SI units are to be regarded as the standard. Reporting test results in units other than SI shall be regarded as conformance with this test method.
1.5.1 In the engineering profession it is customary practice to use, interchangeably, units representing both mass and force, unless dynamic calculations (F=Ma) are involved. This implicitly combines two separate systems of units, that is, the absolute system and the gravimetric system. It is scientifically undesirable to combine two separate systems within a single standard. This test method has been written using SI units; however, inch-pound conversions are given in the gravimetric system, where the pound (lbf) represents a unit of force (weight). The use of balances or scales recording pounds of mass (lbm), or the recording of density in lb/...
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Designation:D6528–00
Standard Test Method for
Consolidated Undrained Direct Simple Shear Testing of
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Cohesive Soils
This standard is issued under the fixed designation D 6528; the number immediately following the designation indicates the year of
original adoption or, in the case of revision, the year of last revision. A number in parentheses indicates the year of last reapproval. A
superscript epsilon (e) indicates an editorial change since the last revision or reapproval.
1. Scope responsibility of the user of this standard to establish appro-
priate safety and health practices and determine the applica-
1.1 This test method defines equipment specifications and
bility of regulatory limitations prior to use.
testing procedures for the measurement of constant volume
strength and stress-strain characteristics of cohesive soils after
2. Referenced Documents
one-dimensional consolidation using a constant rate of simple
2.1 ASTM Standards:
shear deformation mode of loading. The constant volume
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D 422 Test Method for Particle-Size Analysis of Soils
condition is equivalent to the undrained condition for saturated
D 653 Terminology Relating to Soil, Rock and Contained
specimens.
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Fluids
1.2 This test method is written specifically for devices that
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D 854 Test Method for Specific Gravity of Soils
test rectangular parallelepiped or cylindrical specimens. Other
D 1587 Practice for Thin-Walled Tube Geotechnical Sam-
more general devices, such as the torsional shear hollow
2
pling of Soils
cylinder,maybeusedtoperformconsolidatedconstantvolume
D 2216 TestMethodforLaboratoryDeterminationofWater
simple shear tests but are beyond the scope of this test method.
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(Moisture) Content of Soil and Rock
1.3 This test method is applicable to testing both undis-
D 2435 Test Method for One-Dimensional Consolidation
turbed and compacted soils, however, it does not include
2
Properties of Soils
specific guidance for compacting test specimens.
D 2487 Classification of Soils for Engineering Purposes
1.4 It shall be the responsibility of the agency requesting
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(Unified Soil Classification System)
this test to specify the magnitude of the normal consolidation
D 2488 Practice for Description and Identification of Soils
stress prior to constant volume shear and, when appropriate,
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(Visual-Manual Procedure)
the maximum normal consolidation stress, which will result in
2
D 3550 Practice for Ring-Lined Barrel Sampling of Soils
an overconsolidated specimen.
D 3740 Practice for Minimum Requirements for Agencies
1.5 The values stated in SI units are to be regarded as the
Engaged in the Testing and/or Inspection of Soil an Rock
standard. Reporting test results in units other than SI shall be
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as Used in Engineering Design and Construction
regarded as conformance with this test method.
D 4220 Practices for Preserving and Transporting Soil
1.5.1 In the engineering profession it is customary practice
2
Samples
touse,interchangeably,unitsrepresentingbothmassandforce,
D 4318 Test Method for Liquid Limit, Plastic Limit, and
unless dynamic calculations (F=Ma) are involved.This implic-
2
Plasticity Index of Soils
itly combines two separate systems of units, that is, the
2
D 4452 Methods for X-Ray Radiography of Soil Samples
absolute system and the gravimetric system. It is scientifically
undesirable to combine two separate systems within a single
3. Terminology
standard. This test method has been written using SI units;
3.1 Definitions—The terms used in this test method are in
however, inch-pound conversions are given in the gravimetric
accordance with Terminology D 653.
system, where the pound (lbf) represents a unit of force
3.1.1 shear modulus, n—a measure of a material’s resis-
(weight). The use of balances or scales recording pounds of
3 tance to shear stress, equal to the ratio of the increment in the
mass (lbm), or the recording of density in lb/ft should not be
shear stress to the resultant increment in angle of deformation
regarded as nonconformance with this standard.
expressed in radians. Also known as the modulus of rigidity.
1.6 This standard does not purport to address all of the
3.2 Definitions of Terms Specific to This Standard:
safety concerns, if any, associated with its use. It is the
3.2.1 active height control, n—a method of keeping the
height of the specimen constant during the shearing process in
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ThistestmethodisunderthejurisdictionofASTMCommitteeD18onSoiland
Rock and is the direct responsibility of Subcommittee D18.05 on Structural
Properties of Soils.
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Current edition approved Feb. 10, 2000. Published May 2000. Annual Book of ASTM Standards, Vol 04.08.
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.
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D6528–00
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