Standard Test Method for One-Dimensional Consolidation Properties of Saturated Cohesive Soils Using Controlled-Strain Loading

SIGNIFICANCE AND USE
5.1 Information concerning magnitude of compression and rate-of-consolidation of soil is essential in the design of earth structures and earth supported structures. The results of this test method may be used to analyze or estimate one-dimensional settlements, rates of settlement associated with the dissipation of excess pore-water pressure, and rates of fluid transport due to hydraulic gradients. This test method does not provide information concerning the rate of secondary compression.  
5.2 Strain Rate Effects:  
5.2.1 It is recognized that the stress-strain results of consolidation tests are strain rate dependent. Strain rates are limited in this test method by specification of the acceptable magnitudes of the base excess pressure ratio during the loading phase. This specification provides comparable results to the 100 % consolidation (end of primary) compression behavior obtained using Test Method D2435.  
5.2.2 Field strain rates vary greatly with time, depth below the loaded area, and radial distance from the loaded area. Field strain rates during consolidation processes are generally much slower than laboratory strain rates and cannot be accurately determined or predicted. For these reasons, it is not practical to replicate the field strain rates with the laboratory test strain rate.  
5.3 Temperature Effects:  
5.3.1 Temperature affects the rate parameters such as hydraulic conductivity and the coefficient of consolidation. The primary cause of temperature effects is due to the changes in pore fluid viscosity, but soil sensitivity may also be important. This test method provides results under room temperature conditions, corrections may be required to account for specific field conditions. Such corrections are beyond the scope of this test method. Special accommodation may be made to replicate field temperature conditions and still be in conformance with this test method.  
5.4 Saturation Effects:  
5.4.1 This test method may not be used to measur...
SCOPE
1.1 This test method is for the determination of the magnitude and rate-of-consolidation of saturated cohesive soils using continuous controlled-strain axial compression. The specimen is restrained laterally and drained axially to one surface. The axial force and base excess pressure are measured during the deformation process. Controlled strain compression is typically referred to as constant rate-of-strain (CRS) testing.  
1.2 This test method provides for the calculation of total and effective axial stresses, and axial strain from the measurement of axial force, axial deformation, chamber pressure, and base excess pressure. The effective stress is computed using steady state equations.  
1.3 This test method provides for the calculation of the coefficient of consolidation and the hydraulic conductivity throughout the loading process. These values are also based on steady state equations.  
1.4 This test method makes use of steady state equations resulting from a theory formulated under particular assumptions. Subsection 5.5 presents these assumptions.  
1.5 The behavior of cohesive soils is strain rate dependent and hence the results of a CRS test are sensitive to the imposed rate of strain. This test method imposes limits on the strain rate to provide comparable results to the incremental consolidation test (Test Method D2435).  
1.6 The determination of the rate and magnitude of consolidation of soil when it is subjected to incremental loading is covered by Test Method D2435.  
1.7 This test method applies to intact (Group C and Group D of Practice D4220), remolded, or laboratory reconstituted samples.  
1.8 This test method is most often used for materials of relatively low hydraulic conductivity that generate measurable excess base pressures. It may be used to measure the compression behavior of essentially free draining soils but will not provide a measure of the hydraulic conductivity or coefficient of co...

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ASTM D4186/D4186M-20e1 - Standard Test Method for One-Dimensional Consolidation Properties of Saturated Cohesive Soils Using Controlled-Strain Loading
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This international standard was developed in accordance with internationally recognized principles on standardization established in the Decision on Principles for the
Development of International Standards, Guides and Recommendations issued by the World Trade Organization Technical Barriers to Trade (TBT) Committee.
´1
Designation: D4186/D4186M − 20
Standard Test Method for
One-Dimensional Consolidation Properties of Saturated
1
Cohesive Soils Using Controlled-Strain Loading
This standard is issued under the fixed designation D4186/D4186M; 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 (´) indicates an editorial change since the last revision or reapproval.
1
ε NOTE—Section references in 10.1 were editorially corrected in April 2021.
1. Scope* 1.8 This test method is most often used for materials of
relatively low hydraulic conductivity that generate measurable
1.1 This test method is for the determination of the magni-
excess base pressures. It may be used to measure the compres-
tudeandrate-of-consolidationofsaturatedcohesivesoilsusing
sion behavior of essentially free draining soils but will not
continuous controlled-strain axial compression. The specimen
provide a measure of the hydraulic conductivity or coefficient
is restrained laterally and drained axially to one surface. The
of consolidation.
axial force and base excess pressure are measured during the
deformationprocess.Controlledstraincompressionistypically
1.9 All recorded and calculated values shall conform to the
referred to as constant rate-of-strain (CRS) testing.
guideforsignificantdigitsandroundingestablishedinPractice
D6026, unless superseded by this test method. The significant
1.2 Thistestmethodprovidesforthecalculationoftotaland
digits specified throughout this standard are based on the
effective axial stresses, and axial strain from the measurement
assumptionthatdatawillbecollectedoveranaxialstressrange
of axial force, axial deformation, chamber pressure, and base
from 1% of the maximum stress to the maximum stress value.
excess pressure. The effective stress is computed using steady
state equations.
1.9.1 Theproceduresusedtospecifyhowdataarecollected/
recorded and calculated in this standard are regarded as the
1.3 This test method provides for the calculation of the
industry standard. In addition, they are representative of the
coefficient of consolidation and the hydraulic conductivity
significant digits that should generally be retained. The proce-
throughout the loading process.These values are also based on
dures used do not consider material variation, purpose for
steady state equations.
obtaining the data, special purpose studies, or any consider-
1.4 This test method makes use of steady state equations
ations for the user’s objectives; and it is common practice to
resulting from a theory formulated under particular assump-
increase or reduce significant digits of reported data to be
tions. Subsection 5.5 presents these assumptions.
commensuratewiththeseconsiderations.Itisbeyondthescope
1.5 The behavior of cohesive soils is strain rate dependent of this standard to consider significant digits used in analysis
andhencetheresultsofaCRStestaresensitivetotheimposed methods for engineering design.
rateofstrain.Thistestmethodimposeslimitsonthestrainrate
1.9.2 Measurements made to more significant digits or
to provide comparable results to the incremental consolidation
better sensitivity than specified in this standard shall not be
test (Test Method D2435).
regarded a non-conformance with this standard.
1.6 The determination of the rate and magnitude of consoli-
1.10 Units—The values stated in either SI units or inch-
dation of soil when it is subjected to incremental loading is
poundunits[giveninbrackets]aretoberegardedseparatelyas
covered by Test Method D2435.
standard. The values stated in each system may not be exact
1.7 This test method applies to intact (Group C and Group equivalents;therefore,eachsystemshallbeusedindependently
D of Practice D4220), remolded, or laboratory reconstituted of the other. Combining values from the two systems may
samples.
result in non-conformance with the standard. Reporting of test
results in units other than SI shall not be regarded as noncon-
formance with this standard.
1
1.10.1 The gravitational system is used when working with
ThistestmethodisunderthejurisdictionofASTMCommitteeD18onSoiland
Rock and is the direct responsibility of Subcommittee D18.05 on Strength and
inch-pound units. In this system, the pound (lbf) represents a
Compressibility of Soils.
unit of force (weight), while the unit for mass is slugs. The
Current edition approved Nov. 1, 2020. Published November 2020. Originally
ɛ1
rationalized slug unit is not given, unless dynamic (F = ma)
approved in 1982. Last previous edition approved in 2012 as D4186–12 . D
...

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