ASTM D2435/D2435M-11(2020)
(Test Method)Standard Test Methods for One-Dimensional Consolidation Properties of Soils Using Incremental Loading
Standard Test Methods for One-Dimensional Consolidation Properties of Soils Using Incremental Loading
SIGNIFICANCE AND USE
5.1 The data from the consolidation test are used to estimate the magnitude and rate of both differential and total settlement of a structure or earthfill. Estimates of this type are of key importance in the design of engineered structures and the evaluation of their performance.
5.2 The test results can be greatly affected by sample disturbance. Careful selection and preparation of test specimens is required to reduce the potential of disturbance effects.
Note 3: Notwithstanding the statement on precision and bias contained in this standard, the precision of this test method is dependent on the competence of the personnel performing the test and suitability of the equipment and facilities used. Agencies that meet the criteria of Practice D3740 generally are considered capable of competent and objective testing. Users of this test method are cautioned that compliance with Practice D3740 does not assure reliable testing. Reliable testing depends on many factors, and Practice D3740 provides a means of evaluation some of these factors.
5.3 Consolidation test results are dependent on the magnitude of the load increments. Traditionally, the axial stress is doubled for each increment resulting in a load increment ratio of 1. For intact samples, this loading procedure has provided data from which estimates of the preconsolidation stress, using established interpretation techniques, compare favorably with field observations. Other loading schedules may be used to model particular field conditions or meet special requirements. For example, it may be desirable to inundate and load the specimen in accordance with the wetting or loading pattern expected in the field in order to best evaluate the response. Load increment ratios of less than 1 may be desirable for soils that are highly sensitive or whose response is highly dependent on strain rate.
5.4 The interpretation method specified by these test methods to estimate the preconsolidation stress provides a simple te...
SCOPE
1.1 These test methods cover procedures for determining the magnitude and rate of consolidation of soil when it is restrained laterally and drained axially while subjected to incrementally applied controlled-stress loading. Two alternative procedures are provided as follows:
1.1.1 Test Method A—This test method is performed with constant load increment duration of 24 h, or multiples thereof. Time-deformation readings are required on a minimum of two load increments. This test method provides only the compression curve of the specimen and the results combine both primary consolidation and secondary compression deformations.
1.1.2 Test Method B—Time-deformation readings are required on all load increments. Successive load increments are applied after 100 % primary consolidation is reached, or at constant time increments as described in Test Method A. This test method provides the compression curve with explicit data to account for secondary compression, the coefficient of consolidation for saturated materials, and the rate of secondary compression.
Note 1: The determination of the rate and magnitude of consolidation of soil when it is subjected to controlled-strain loading is covered by Test Method D4186/D4186M.
1.2 These test methods are most commonly performed on saturated intact samples of fine grained soils naturally sedimented in water, however, the basic test procedure is applicable, as well, to specimens of compacted soils and intact samples of soils formed by other processes such as weathering or chemical alteration. Evaluation techniques specified in these test methods assume the pore space is fully saturated and are generally applicable to soils naturally sedimented in water. Tests performed on other unsaturated materials such as compacted and residual (weathered or chemically altered) soils may require special evaluation techniques. In particular, the rate of consolidation (interpretation of the time ...
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Standards Content (Sample)
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.
Designation: D2435/D2435M − 11 (Reapproved 2020)
Standard Test Methods for
One-Dimensional Consolidation Properties of Soils Using
Incremental Loading
This standard is issued under the fixed designation D2435/D2435M; 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. Scope rate of consolidation (interpretation of the time curves) is only
applicable to fully saturated specimens.
1.1 These test methods cover procedures for determining
the magnitude and rate of consolidation of soil when it is
1.3 It shall be the responsibility of the agency requesting
restrained laterally and drained axially while subjected to
this test to specify the magnitude and sequence of each load
incrementally applied controlled-stress loading. Two alterna-
increment, including the location of a rebound cycle, if
tive procedures are provided as follows:
required, and, for Test Method A, the load increments for
1.1.1 Test Method A—This test method is performed with
which time-deformation readings are desired. The required
constant load increment duration of 24 h, or multiples thereof.
maximum stress level depends on the purpose of the test and
Time-deformation readings are required on a minimum of two
must be agreed on with the requesting agency. In the absence
load increments. This test method provides only the compres-
of specific instructions, Section 11 provides the default load
sion curve of the specimen and the results combine both
increment and load duration schedule for a standard test.
primary consolidation and secondary compression deforma-
tions. NOTE 2—Time-deformation readings are required to determine the time
for completion of primary consolidation and for evaluating the coefficient
1.1.2 Test Method B—Time-deformation readings are re-
of consolidation, c . Since c varies with stress level and loading type
v v
quired on all load increments. Successive load increments are
(loading or unloading), the load increments with timed readings must be
applied after 100 % primary consolidation is reached, or at
selected with specific reference to the individual project.Alternatively, the
constant time increments as described in Test Method A. This
requesting agency may specify Test Method B wherein the time-
test method provides the compression curve with explicit data
deformation readings are taken on all load increments.
to account for secondary compression, the coefficient of
1.4 These test methods do not address the use of a back
consolidation for saturated materials, and the rate of secondary
pressure to saturate the specimen. Equipment is available to
compression.
perform consolidation tests using back pressure saturation.The
NOTE 1—The determination of the rate and magnitude of consolidation
addition of back pressure saturation does not constitute non-
of soil when it is subjected to controlled-strain loading is covered by Test
conformance to these test methods.
Method D4186/D4186M.
1.5 Units—The values stated in either SI units or inch-
1.2 These test methods are most commonly performed on
pound units [given in brackets] are to be regarded separately as
saturated intact samples of fine grained soils naturally sedi-
standard. The values stated in each system may not be exact
mented in water, however, the basic test procedure is
equivalents;therefore,eachsystemshallbeusedindependently
applicable, as well, to specimens of compacted soils and intact
of the other. Combining values from the two systems may
samples of soils formed by other processes such as weathering
result in non-conformance with the standard.
or chemical alteration. Evaluation techniques specified in these
test methods assume the pore space is fully saturated and are
1.5.1 In the engineering profession it is customary practice
generally applicable to soils naturally sedimented in water. touse,interchangeably,unitsrepresentingbothmassandforce,
Tests performed on other unsaturated materials such as com-
unless dynamic calculations (F = Ma) are involved. This im-
pacted and residual (weathered or chemically altered) soils
plicitly combines two separate systems of units, that is, the
may require special evaluation techniques. In particular, 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;
1 however, inch-pound conversions are given in the gravimetric
These test methods are under the jurisdiction ofASTM Committee D18 on Soil
and Rock and is the direct responsibility of Subcommittee D18.05 on Strength and
system, where the pound (lbf) represents a unit of force
Compressibility of Soils.
(weight). The use of balances or scales recording pounds of
Current edition approved April 1, 2020. Published April 2020. Originally
mass (lbm), or the recording of density in lb/ft should not be
approved in 1965. Last previous edition approved in 2011 as D2435–11. DOI:
10.1520/D2435_D2435M-11R20. regarded as nonconformance with this test method.
*A Summary of Changes section appears at the end of this standard
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States
D2435/D2435M − 11 (2020)
1.6 Observed and calculated values shall conform to the D4753 Guide for Evaluating, Selecting, and Specifying Bal-
guidelines for significant digits and rounding established in ances and Standard Masses for Use in Soil, Rock, and
Practice D6026, unless superseded by this test method. Construction Materials Testing
1.6.1 The method used to specify how data are collected, D6026 Practice for Using Significant Digits in Geotechnical
calculated, or recorded in this standard is not directly related to Data
theaccuracytowhichthedatacanbeappliedindesignorother D6027/D6027M Practice for Calibrating Linear Displace-
uses, or both. How one applies the results obtained using this ment Transducers for Geotechnical Purposes
standard is beyond its scope.
3. Terminology
1.7 This standard does not purport to address all of the
safety concerns, if any, associated with its use. It is the
3.1 For definitions of technical terms used in these test
responsibility of the user of this standard to establish appro-
methods, see Terminology D653.
priate safety, health, and environmental practices and deter-
3.2 Definitions of Terms Specific to This Standard:
mine the applicability of regulatory limitations prior to use.
3.2.1 axial deformation (L, L, %, or -), n—the change in
1.8 This international standard was developed in accor-
axial dimension of the specimen which can be expressed in
dance with internationally recognized principles on standard-
terms of length, height of specimen, strain or void ratio.
ization established in the Decision on Principles for the
Development of International Standards, Guides and Recom- 3.2.2 estimated preconsolidation stress (F/L ), n—the value
mendations issued by the World Trade Organization Technical of the preconsolidation stress determined by the technique
Barriers to Trade (TBT) Committee. prescribed in these test methods for the purpose of aiding the
laboratory in the performance of the test. This estimation
should not be considered equivalent to an engineering inter-
2. Referenced Documents
2 pretation of the test measurements.
2.1 ASTM Standards:
3.2.3 load (F), n—in the context of soil testing, the act of
D422 Test Method for Particle-SizeAnalysis of Soils (With-
drawn 2016) applying force or deformation to the boundary of a test
specimen.Intheincrementalconsolidationtestthisisgenerally
D653 Terminology Relating to Soil, Rock, and Contained
Fluids performed using weights on a hanger.
D854 Test Methods for Specific Gravity of Soil Solids by
3.2.4 load increment, n—one individual step of the test
Water Pycnometer
duringwhichthespecimenisunderaconstanttotalaxialstress.
D1587/D1587M Practice for Thin-Walled Tube Sampling of
3.2.5 load increment duration (T), n—thelengthoftimethat
Fine-Grained Soils for Geotechnical Purposes
one value of total axial stress is maintained on the specimen.
D2216 Test Methods for Laboratory Determination of Water
(Moisture) Content of Soil and Rock by Mass 3.2.6 load increment ratio, LIR (-), n—the change (increase
or decrease) in total axial stress to be applied to the specimen
D2487 Practice for Classification of Soils for Engineering
Purposes (Unified Soil Classification System) in a single step divided by the current total axial stress.
D2488 Practice for Description and Identification of Soils 3.2.6.1 Discussion—Load Increment Ratio is historically
(Visual-Manual Procedures)
used in consolidation testing to reflect the fact that the test was
D3550/D3550M Practice for Thick Wall, Ring-Lined, Split performed by adding weights to apply the total axial stress to
Barrel, Drive Sampling of Soils
the specimen.
D3740 Practice for Minimum Requirements for Agencies 2
3.2.7 total axial stress (F/L ), n—the force acting on the
Engaged in Testing and/or Inspection of Soil and Rock as
specimen divided by the specimen area. Once consolidation is
Used in Engineering Design and Construction
complete, the effective axial stress is assumed to equal the total
D4186/D4186M TestMethodforOne-DimensionalConsoli-
axial stress.
dation Properties of Saturated Cohesive Soils Using
3.2.8 total axial stress increment (F/L ), n—the change
Controlled-Strain Loading
(increase or decrease) in total axial stress applied in one single
D4220/D4220M Practices for Preserving and Transporting
step. The change may be an increase or a decrease in stress.
Soil Samples
D4318 Test Methods for Liquid Limit, Plastic Limit, and
4. Summary of Test Methods
Plasticity Index of Soils
D4452 Practice for X-Ray Radiography of Soil Samples
4.1 In these test methods a soil specimen is restrained
D4546 Test Methods for One-Dimensional Swell or Col-
laterally and loaded axially with total stress increments. Each
lapse of Soils
stress increment is maintained until excess pore water pres-
sures are essentially dissipated. Pore pressure is assumed to be
dissipated based on interpretation of the time deformation
underconstanttotalstress.Thisinterpretationisfoundedonthe
For referenced ASTM standards, visit the ASTM website, www.astm.org, or
contact ASTM Customer Service at service@astm.org. For Annual Book of ASTM
assumption that the soil is 100% saturated. Measurements are
Standards volume information, refer to the standard’s Document Summary page on
made of change in the specimen height and these data are used
the ASTM website.
to determine the relationship between the effective axial stress
The last approved version of this historical standard is referenced on
www.astm.org. and void ratio or strain. When time deformation readings are
D2435/D2435M − 11 (2020)
taken throughout an increment, the rate of consolidation is 5.6 The apparatus in general use for these test methods do
evaluated with the coefficient of consolidation. not have provisions for verification of saturation. Most intact
samples taken from below the water table will be saturated.
5. Significance and Use However, the time rate of deformation is very sensitive to
degree of saturation and caution must be exercised regarding
5.1 The data from the consolidation test are used to estimate
estimates for duration of settlements when partially saturated
the magnitude and rate of both differential and total settlement
conditions prevail. Inundation of the test specimen does not
of a structure or earthfill. Estimates of this type are of key
significantly change the degree of saturation of the test
importance in the design of engineered structures and the
specimen but rather provides boundary water to eliminate
evaluation of their performance.
negative pore pressure associated with sampling and prevents
evaporation during the test. The extent to which partial
5.2 The test results can be greatly affected by sample
saturation influences the test results may be a part of the test
disturbance. Careful selection and preparation of test speci-
evaluation and may include application of theoretical models
mens is required to reduce the potential of disturbance effects.
other than conventional consolidation theory.Alternatively, the
NOTE 3—Notwithstanding the statement on precision and bias con-
test may be performed using an apparatus equipped to saturate
tained in this standard, the precision of this test method is dependent on
the specimen.
the competence of the personnel performing the test and suitability of the
equipment and facilities used. Agencies that meet the criteria of Practice
5.7 These test methods use conventional consolidation
D3740 generally are considered capable of competent and objective
theory based on Terzaghi’s consolidation equation to compute
testing. Users of this test method are cautioned that compliance with
the coefficient of consolidation, c . The analysis is based upon
v
Practice D3740 does not assure reliable testing. Reliable testing depends
the following assumptions:
onmanyfactors,andPracticeD3740providesameansofevaluationsome
of these factors.
5.7.1 The soil is saturated and has homogeneous properties;
5.7.2 The flow of pore water is in the vertical direction;
5.3 Consolidation test results are dependent on the magni-
5.7.3 The compressibility of soil particles and pore water is
tude of the load increments. Traditionally, the axial stress is
negligible compared to the compressibility of the soil skeleton;
doubled for each increment resulting in a load increment ratio
5.7.4 The stress-strain relationship is linear over the load
of 1. For intact samples, this loading procedure has provided
increment;
data from which estimates of the preconsolidation stress, using
5.7.5 The ratio of soil permeability to soil compressibility is
established interpretation techniques, compare favorably with
constant over the load increment; and
field observations. Other loading schedules may be used to
5.7.6 Darcy’s law for flow through porous media applies.
model particular field conditions or meet special requirements.
For example, it may be desirable to inundate and load the
6. Apparatus
specimen in accordance with the wetting or loading pattern
expected in the field in order to best evaluate the response.
6.1 Load Device—Asuitable device for applying axial loads
Load increment ratios of less
...
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