ASTM D4767-11(2020)

Standard Test Method for Consolidated Undrained Triaxial Compression Test for Cohesive Soils

SIGNIFICANCE AND USE
4.1 The shear strength of a saturated soil in triaxial compression depends on the stresses applied, time of consolidation, strain rate, and the stress history experienced by the soil.  
4.2 In this test method, the shear characteristics are measured under undrained conditions and is applicable to field conditions where soils that have been fully consolidated under one set of stresses are subjected to a change in stress without time for further consolidation to take place (undrained condition), and the field stress conditions are similar to those in the test method.
Note 1: If the strength is required for the case where the soil is not consolidated during testing prior to shear, refer to Test Method D2850 or Test Method D2166/D2166M.  
4.3 Using the pore-water pressure measured during the test, the shear strength determined from this test method can be expressed in terms of effective stress. This shear strength may be applied to field conditions where full drainage can occur (drained conditions) or where pore pressures induced by loading can be estimated, and the field stress conditions are similar to those in the test method.  
4.4 The shear strength determined from the test expressed in terms of total stresses (undrained conditions) or effective stresses (drained conditions) is commonly used in embankment stability analyses, earth pressure calculations, and foundation design.
Note 2: Notwithstanding the statements on precision and bias contained in this test method. The precision of this test method is dependent on the competence of the personnel performing it and the suitability of the equipment and facilities used. Agencies which meet the criteria of Practice D3740 are generally considered capable of competent testing. Users of this test method are cautioned that compliance with Practice D3740 does not ensure reliable testing. Reliable testing depends on several factors; Practice D3740 provides a means of evaluating some of those factors.
SCOPE
1.1 This test method covers the determination of strength and stress-strain relationships of a cylindrical specimen of either an intact, reconstituted, or remolded saturated cohesive soil. Specimens are isotropically consolidated and sheared in compression without drainage at a constant rate of axial deformation (strain controlled).  
1.2 This test method provides for the calculation of total and effective stresses, and axial compression by measurement of axial load, axial deformation, and pore-water pressure.  
1.3 This test method provides data useful in determining strength and deformation properties of cohesive soils such as Mohr strength envelopes and Young's modulus. Generally, three specimens are tested at different effective consolidation stresses to define a strength envelope.  
1.4 The determination of strength envelopes and the development of relationships to aid in interpreting and evaluating test results are beyond the scope of this test method and must be performed by a qualified, experienced professional.  
1.5 All observed and calculated values shall conform to the guidelines for significant digits and rounding established in Practice D6026.  
1.5.1 The methods used to specify how data are collected, calculated, or recorded in this standard are regarded as the industry standard. In addition, they are representative of the significant digits that generally should be retained. The procedures used do not consider material variation, purpose for obtaining the data, special purpose studies or any consideration of end use. It is beyond the scope of this test method to consider significant digits used in analysis methods for engineering design.  
1.6 Units—The values stated in SI units are to be regarded as standard. The values given in parentheses are provided for information only and are not considered standard. Reporting of test results in units other than SI shall not be regarded as nonconformance with this test method.  
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General Information

• Status: Published
• Publication Date: 31-Mar-2020
• ICS: 93.020 - Earthworks. Excavations. Foundation construction. Underground works
• Technical Committee: D18 - Soil and Rock
• Drafting Committee: D18.05 - Strength and Compressibility of Soils

Relations

• Replaces: ASTM D4767-11 - Standard Test Method for Consolidated Undrained Triaxial Compression Test for Cohesive Soils
• Effective Date: 01-Apr-2020
• Refers: ASTM D4753-24 - Standard Guide for Evaluating, Selecting, and Specifying Balances and Standard Masses for Use in Soil, Rock, and Construction Materials Testing
• Effective Date: 01-Feb-2024
• Refers: ASTM D3740-23 - Standard Practice for Minimum Requirements for Agencies Engaged in Testing and/or Inspection of Soil and Rock as Used in Engineering Design and Construction
• Effective Date: 01-Nov-2023
• Refers: ASTM D854-23 - Standard Test Methods for Specific Gravity of Soil Solids by the Water Displacement Method
• Effective Date: 01-Nov-2023
• Refers: ASTM D3740-19 - Standard Practice for Minimum Requirements for Agencies Engaged in Testing and/or Inspection of Soil and Rock as Used in Engineering Design and Construction
• Effective Date: 01-Oct-2019
• Refers: ASTM D2216-19 - Standard Test Methods for Laboratory Determination of Water (Moisture) Content of Soil and Rock by Mass
• Effective Date: 01-Mar-2019
• Refers: ASTM D4318-17 - Standard Test Methods for Liquid Limit, Plastic Limit, and Plasticity Index of Soils
• Effective Date: 01-Jun-2017
• Refers: ASTM D4318-17e1 - Standard Test Methods for Liquid Limit, Plastic Limit, and Plasticity Index of Soils
• Effective Date: 01-Jun-2017
• Refers: ASTM D1587/D1587M-15 - Standard Practice for Thin-Walled Tube Sampling of Fine-Grained Soils for Geotechnical Purposes (Withdrawn 2024)
• Effective Date: 15-Nov-2015
• Refers: ASTM D4753-15 - Standard Guide for Evaluating, Selecting, and Specifying Balances and Standard Masses for Use in Soil, Rock, and Construction Materials Testing
• Effective Date: 01-May-2015
• Refers: ASTM D653-14 - Standard Terminology Relating to Soil, Rock, and Contained Fluids
• Effective Date: 01-Aug-2014
• Refers: ASTM D2166/D2166M-13 - Standard Test Method for Unconfined Compressive Strength of Cohesive Soil
• Effective Date: 15-May-2013
• Refers: ASTM D3740-12a - Standard Practice for Minimum Requirements for Agencies Engaged in Testing and/or Inspection of Soil and Rock as Used in Engineering Design and Construction
• Effective Date: 01-May-2012
• Refers: ASTM D3740-12 - Standard Practice for Minimum Requirements for Agencies Engaged in Testing and/or Inspection of Soil and Rock as Used in Engineering Design and Construction
• Effective Date: 01-Mar-2012
• Refers: ASTM D653-11 - Standard Terminology Relating to Soil, Rock, and Contained Fluids
• Effective Date: 01-Sep-2011

Overview

ASTM D4767-11(2020), titled "Standard Test Method for Consolidated Undrained Triaxial Compression Test for Cohesive Soils," is a widely recognized standard developed by ASTM International. This test method is essential in geotechnical engineering for determining the shear strength and stress-strain relationships of cylindrical specimens of saturated, cohesive soils. By simulating undrained field conditions where soils are subjected to rapid changes in stress without sufficient time for drainage, ASTM D4767 provides accurate and practical data used in the analysis and design of embankments, foundations, and other earth structures.

Key Topics

• Shear Strength Determination: Measures soil strength under undrained conditions-reflecting field situations where water cannot drain from soil pores quickly after loading.
• Stress-Strain Relationships: Examines how saturated, cohesive soils deform and withstand stress during triaxial compression.
• Consolidation and Loading: Uses isotropically consolidated specimens that are sheared at a constant rate of axial deformation (strain-controlled).
• Measurement Capabilities: Enables the calculation of both total and effective stresses through axial load, deformation, and pore-water pressure readings.
• Data Outputs: Provides the foundation for determining Mohr strength envelopes and parameters like Young’s modulus, assisting in the broader evaluation of soil deformation properties.
• Precision and Competency: Requires specialized equipment and skilled personnel, highlighting the importance of following established laboratory practices.

Applications

The ASTM D4767 triaxial compression test is a cornerstone procedure in soil mechanics and geotechnical design with broad practical applications, including:

• Embankment Stability Analysis: Assessing the strength of the foundation soils to prevent slope failures.
• Earth Pressure Calculations: Key parameter estimation for retaining structure and excavation designs.
• Foundation Engineering: Supporting the safe design of shallow and deep foundations for buildings, bridges, and infrastructure.
• Soil Improvement Assessment: Evaluating the impact of soil treatment techniques or ground improvement methods on strength characteristics.
• Risk Evaluation: Understanding how soils will perform during rapid loading situations, such as earthquakes or construction loading sequences.
• Design Inputs: Test results often serve as primary inputs for geotechnical modeling, such as finite element analysis and limit equilibrium methods.

Related Standards

Comprehensive soil testing and reporting often require the use of several ASTM standards. Relevant documents include:

• ASTM D653: Terminology Relating to Soil, Rock, and Contained Fluids
• ASTM D1587/D1587M: Practice for Thin-Walled Tube Sampling of Fine-Grained Soils
• ASTM D2166/D2166M: Test Method for Unconfined Compressive Strength of Cohesive Soil
• ASTM D2216: Test Method for Laboratory Determination of Water (Moisture) Content of Soil and Rock
• ASTM D2435/D2435M: Test Methods for One-Dimensional Consolidation Properties of Soils Using Incremental Loading
• ASTM D2850: Test Method for Unconsolidated-Undrained Triaxial Compression Test on Cohesive Soils
• ASTM D3740: Practice for Minimum Requirements for Agencies Engaged in Testing and/or Inspection of Soil and Rock
• ASTM D4318: Test Methods for Liquid Limit, Plastic Limit, and Plasticity Index of Soils
• ASTM D4753: Guide for Evaluating, Selecting, and Specifying Balances and Standard Masses
• ASTM D6026: Practice for Using Significant Digits in Geotechnical Data

Practical Value

Implementing ASTM D4767 in laboratory and field contexts ensures that engineers and designers obtain reliable, reproducible data critical to the safety and performance of earth structures. By following this test method, practitioners can:

• Confidently predict the undrained shear strength of cohesive soils.
• Reflect realistic site conditions in design by accounting for consolidation history and undrained loading.
• Satisfy regulatory and safety standards in geotechnical investigations and design submissions.
• Support best practices in soil mechanics testing, contributing to safer, more durable infrastructure projects.

For geotechnical engineers, soil mechanics laboratories, and construction professionals committed to high standards, ASTM D4767 remains a fundamental test method for modern earthwork analysis and design.

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: D4767 − 11 (Reapproved 2020)
Standard Test Method for
Consolidated Undrained Triaxial Compression Test for
Cohesive Soils
This standard is issued under the fixed designation D4767; the number immediately following the designation indicates the year of
original adoption or, in the case of revision, the year of last revision.Anumber in parentheses indicates the year of last reapproval.A
superscript epsilon (´) indicates an editorial change since the last revision or reapproval.
1. Scope test results in units other than SI shall not be regarded as
nonconformance with this test method.
1.1 This test method covers the determination of strength
1.6.1 The gravitational system of inch-pound units is used
and stress-strain relationships of a cylindrical specimen of
when dealing with inch-pound units. In this system, the pound
either an intact, reconstituted, or remolded saturated cohesive
(lbf)representsaunitofforce(weight),whiletheunitformass
soil. Specimens are isotropically consolidated and sheared in
is slugs. The slug unit is not given, unless dynamic (F = ma)
compression without drainage at a constant rate of axial
calculations are involved.
deformation (strain controlled).
1.6.2 It is common practice in the engineering/construction
1.2 Thistestmethodprovidesforthecalculationoftotaland
profession to concurrently use pounds to represent both a unit
effective stresses, and axial compression by measurement of
of mass (lbm) and of force (lbf). This implicitly combines two
axial load, axial deformation, and pore-water pressure.
separate systems of units; that is, the absolute system and the
gravitational system. It is scientifically undesirable to combine
1.3 This test method provides data useful in determining
strength and deformation properties of cohesive soils such as the use of two separate sets of inch-pound units within a single
standard. As stated, this standard includes the gravitational
Mohr strength envelopes and Young’s modulus. Generally,
three specimens are tested at different effective consolidation system of inch-pound units and does not use/present the slug
unitformass.However,theuseofbalancesorscalesrecording
stresses to define a strength envelope.
pounds of mass (lbm) or recording density in lbm/ft shall not
1.4 The determination of strength envelopes and the devel-
be regarded as nonconformance with this standard.
opment of relationships to aid in interpreting and evaluating
1.6.3 The terms density and unit weight are often used
test results are beyond the scope of this test method and must
interchangeably. Density is mass per unit volume whereas unit
be performed by a qualified, experienced professional.
weight is force per unit volume. In this standard density is
1.5 All observed and calculated values shall conform to the
given only in SI units. After the density has been determined,
guidelines for significant digits and rounding established in
the unit weight is calculated in SI or inch-pound units, or both.
Practice D6026.
1.7 This standard does not purport to address all of the
1.5.1 The methods used to specify how data are collected,
safety concerns, if any, associated with its use. It is the
calculated, or recorded in this standard are regarded as the
responsibility of the user of this standard to establish appro-
industry standard. In addition, they are representative of the
priate safety, health, and environmental practices and deter-
significant digits that generally should be retained. The proce-
mine the applicability of regulatory limitations prior to use.
dures used do not consider material variation, purpose for
1.8 This international standard was developed in accor-
obtainingthedata,specialpurposestudiesoranyconsideration
dance with internationally recognized principles on standard-
of end use. It is beyond the scope of this test method to
ization established in the Decision on Principles for the
consider significant digits used in analysis methods for engi-
Development of International Standards, Guides and Recom-
neering design.
mendations issued by the World Trade Organization Technical
1.6 Units—The values stated in SI units are to be regarded
Barriers to Trade (TBT) Committee.
as standard. The values given in parentheses are provided for
informationonlyandarenotconsideredstandard.Reportingof
2. Referenced Documents
2.1 ASTM Standards:
ThistestmethodisunderthejurisdictionofASTMCommitteeD18onSoiland
Rock and is the direct responsibility of Subcommittee D18.05 on Strength and
Compressibility of Soils. For referenced ASTM standards, visit the ASTM website, www.astm.org, or
Current edition approved April 1, 2020. Published April 2020. Originally contact ASTM Customer Service at [e-mail]. For Annual Book of ASTM
approved in 1988. Last previous edition approved in 2011 as D4767–11. DOI: Standards volume information, refer to the standard’s Document Summary page on
10.1520/D4767-11R20. the ASTM website.
*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
D4767 − 11 (2020)
D422Test Method for Particle-SizeAnalysis of Soils (With- 4.2 In this test method, the shear characteristics are mea-
drawn 2016) sured under undrained conditions and is applicable to field
D653Terminology Relating to Soil, Rock, and Contained conditions where soils that have been fully consolidated under
Fluids one set of stresses are subjected to a change in stress without
D854Test Methods for Specific Gravity of Soil Solids by time for further consolidation to take place (undrained
Water Pycnometer condition),andthefieldstressconditionsaresimilartothosein
D1587/D1587MPractice forThin-WalledTube Sampling of the test method.
Fine-Grained Soils for Geotechnical Purposes
NOTE 1—If the strength is required for the case where the soil is not
D2166/D2166MTest Method for Unconfined Compressive
consolidated during testing prior to shear, refer to Test Method D2850 or
Strength of Cohesive Soil Test Method D2166/D2166M.
D2216Test Methods for Laboratory Determination ofWater
4.3 Using the pore-water pressure measured during the test,
(Moisture) Content of Soil and Rock by Mass
the shear strength determined from this test method can be
D2435/D2435MTest Methods for One-Dimensional Con-
expressed in terms of effective stress. This shear strength may
solidation Properties of Soils Using Incremental Loading
be applied to field conditions where full drainage can occur
D2850Test Method for Unconsolidated-Undrained Triaxial
(drained conditions) or where pore pressures induced by
Compression Test on Cohesive Soils
loading can be estimated, and the field stress conditions are
D3740Practice for Minimum Requirements for Agencies
similar to those in the test method.
Engaged in Testing and/or Inspection of Soil and Rock as
4.4 Theshearstrengthdeterminedfromthetestexpressedin
Used in Engineering Design and Construction
terms of total stresses (undrained conditions) or effective
D4220/D4220MPractices for Preserving and Transporting
stresses(drainedconditions)iscommonlyusedinembankment
Soil Samples
stability analyses, earth pressure calculations, and foundation
D4318Test Methods for Liquid Limit, Plastic Limit, and
design.
Plasticity Index of Soils
D4753Guide for Evaluating, Selecting, and Specifying Bal- NOTE 2—Notwithstanding the statements on precision and bias con-
tained in this test method. The precision of this test method is dependent
ances and Standard Masses for Use in Soil, Rock, and
onthecompetenceofthepersonnelperformingitandthesuitabilityofthe
Construction Materials Testing
equipmentandfacilitiesused.AgencieswhichmeetthecriteriaofPractice
D6026Practice for Using Significant Digits in Geotechnical
D3740 are generally considered capable of competent testing. Users of
Data
this test method are cautioned that compliance with Practice D3740 does
not ensure reliable testing. Reliable testing depends on several factors;
3. Terminology
Practice D3740 provides a means of evaluating some of those factors.
3.1 Definitions—For standard definitions of common tech-
5. Apparatus
nical terms, refer to Terminology D653.
5.1 The requirements for equipment needed to perform
3.2 Definitions of Terms Specific to This Standard:
satisfactory tests are given in the following sections. See Fig.
3.2.1 back pressure—a pressure applied to the specimen
1 and Fig. 2
pore-water to cause air in the pore space to compress and to
5.2 Axial Loading Device—The axial loading device shall
pass into solution in the pore-water thereby increasing the
be a screw jack driven by an electric motor through a geared
percent saturation of the specimen.
transmission, a hydraulic loading device, or any other com-
3.2.2 effective consolidation stress—the difference between
pression device with sufficient capacity and control to provide
the cell pressure and the pore-water pressure prior to shearing
therateofaxialstrain(loading)prescribedin8.4.2.Therateof
the specimen.
advance of the loading device shall not deviate by more than
61% from the selected value. Vibration due to the operation
3.2.3 failure—a maximum-stress condition or stress at a
of the loading device shall be sufficiently small to not cause
defined strain for a test specimen. Failure is often taken to
dimensional changes in the specimen or to produce changes in
correspond to the maximum principal stress difference (maxi-
pore-water pressure when the drainage valves are closed.
mum deviator stress) attained or the principal stress difference
(deviatorstress)at15%axialstrain,whicheverisobtainedfirst
NOTE 3—Aloading device may be judged to produce sufficiently small
during the performance of a test. Depending on soil behavior
vibrations if there are no visible ripples in a glass of water placed on the
and field application, other suitable failure criteria may be loading platform when the device is operating at the speed at which the
test is performed.
defined, such as maximum effective stress obliquity, (σ '/
σ ') , or the principal stress difference (deviator stress) at a 5.3 Axial Load-Measuring Device—The axial load-
3 max
selected axial strain other than 15%. measuring device shall be an electronic load cell, hydraulic
load cell, or any other load-measuring device capable of the
4. Significance and Use
accuracy prescribed in this paragraph and may be a part of the
4.1 The shear strength of a saturated soil in triaxial com- axial loading device. The axial load-measuring device shall be
pressiondependsonthestressesapplied,timeofconsolidation, capable of measuring the axial load to an accuracy of within
strain rate, and the stress history experienced by the soil. 1% of the axial load at failure. If the load-measuring device is
located inside the triaxial compression chamber, it shall be
insensitive to horizontal forces and to the magnitude of the
The last approved version of this historical standard is referenced on
www.astm.org. chamber pressure.
D4767 − 11 (2020)
FIG. 1 Schematic Diagram of a Typical Consolidated Undrained Triaxial Apparatus
FIG. 2 Filter Strip Cage
5.4 Triaxial Compression Chamber—The triaxial chamber specimen base and to the cap to allow saturation and drainage
shall have a working chamber pressure equal to the sum of the of the specimen when required. The chamber shall provide a
effective consolidation stress and the back pressure. It shall connection to the cap.
consist of a top plate and a base plate separated by a cylinder.
5.5 Axial Load Piston—The piston passing through the top
The cylinder may be constructed of any material capable of
of the chamber and its seal must be designed so the variation
withstanding the applied pressures. It is desirable to use a
in axial load due to friction does not exceed 0.1% of the axial
transparent material or have a cylinder provided with viewing
load at failure and so there is negligible lateral bending of the
portssothebehaviorofthespecimenmaybeobserved.Thetop
piston during loading.
plate shall have a vent valve such that air can be forced out of
the chamber as it is filled. The baseplate shall have an inlet
NOTE 4—The use of two linear ball bushings to guide the piston is
through which to fill the chamber, and inlets leading to the recommended to minimize friction and maintain alignment.
D4767 − 11 (2020)
NOTE 5—Aminimum piston diameter of ⁄6 the specimen diameter has pressure, and record the volume change.
been used successfully in many laboratories to minimize lateral bending.
5.9 Volume Change Measurement Device—The volume of
5.6 Pressure and Vacuum-Control Devices—The chamber
water entering or leaving the specimen shall be measured with
pressure and back pressure control devices shall be capable of
an accuracy of within 60.05% of the total volume of the
applying and controlling pressures to within 62 kPa (0.25
specimen. The volume measuring device is usually a burette
lb/in. ) for effective consolidation pressures less than 200 kPa
connected to the back pressure but may be any other device
(28 lbf/in. ) and to within 61% for effective consolidation
meeting the accuracy requirement. The device must be able to
pressures greater than 200 kPa. The vacuum-control device
withstand the maximum back pressure.
shallbecapableofapplyingandcontrollingpartialvacuumsto
5.10 Deformation Indicator—The vertical deformation of
within 62 kPa. The devices shall consist of pressure/volume
thespecimenisusuallydeterminedfromthetravelofthepiston
controllers pneumatic pressure regulators, combination pneu-
acting on the top of the specimen. The piston travel shall be
matic pressure and vacuum regulators, or any other device
capable of applying and controlling pressures or partial vacu- measured with an accuracy of at least 0.25% of the initial
specimen height. The deformation indicator shall have a range
ums to the required tolerances. These tests can require a test
duration of several day. Therefore, an air/water interface is not of at least 15% of the initial height of the specimen and may
be a dial indicator or other measuring device meeting the
recommended for either the chamber pressure or back pressure
systems, unless isolated from the specimen and chamber (for requirements for accuracy and range.
example, by long tubing).
5.11 Specimen Cap and Base—The specimen cap and base
5.7 Pressure- and Vacuum-Measurement Devices—The
shall be designed to provide drainage from both ends of the
chamber pressure-, back pressure-, and vacuum-measuring
specimen. They shall be constructed of a rigid, noncorrosive,
devices shall be capable of measuring pressures or partial
impermeable material, and each shall, except for the drainage
vacuums to the tolerances given in 5.6. They may consist of
provision, have a circular plane surface of contact with the
electronic pressure transducers, or any other device capable of
porous disks and a circular cross section. It is desirable for the
measuring pressures, or partial vacuums to the stated toler-
massofthespecimencapandtopporousdisktobeasminimal
ances. If separate devices are used to measure the chamber
aspossible.However,themassmaybeasmuchas10%ofthe
pressure and back pressure, the devices must be calibrated
axial load at failure. If the mass is greater than 0.5% of the
simultaneouslyandagainstthesamepressuresource.Sincethe
appliedaxialloadatfailureandgreaterthan50g,theaxialload
chamber and back pressure are the pressures taken at the
must be corrected for the mass of the specimen cap and top
mid-height of the specimen, it may be necessary to adjust the
porous disk.The diameter of the cap and base shall be equal to
calibration of the devices to reflect the hydraulic head of fluids
the initial diameter of the specimen. The specimen base shall
in the chamber and back pressure control systems.
be connected to the triaxial compression chamber to prevent
lateral motion or tilting, and the specimen cap shall be
5.8 Pore-Water Pressure-Measurement Device—The speci-
designed such that eccentricity of the piston-to-cap contact
men pore-water pressure shall also be measured to the toler-
ances given in 5.6. During undrained shear, the pore-water relativetotheverticalaxisofthespecimendoesnotexceed1.3
mm (0.05 in.).The end of the piston and specimen cap contact
pressureshallbemeasuredinsuchamannerthataslittlewater
as possible is allowed to go into or out of the specimen. To areashallbedesignedsothattiltingofthespecimencapduring
the test is minimal. The cylindrical surface of the specimen
achieve this requirement, a very stiff electronic pressure
transducer or null-indicating device must be used. With an baseandcapthatcontactsthemembranetoformasealshallbe
smooth and free of scratches.
electronic pressure transducer the pore-water pressure is read
directly. With a null-indicating device a pressure control is
5.12 Porous Discs—Two rigid porous disks shall be used to
continuously adjusted to maintain a constant level of the
providedrainageattheendsofthespecimen.Thecoefficientof
water/mercuryinterfaceinthecapillaryboreofthedevice.The
permeability of the disks shall be approximately equal to that
pressure required to prevent movement of the water is equal to
−4 −5
of fine sand (1×10 cm/s (4×10 in./s)).The disks shall be
the pore-water pressure. Both measuring devices shall have a
regularly cleaned by ultrasonic or boiling and brushing and
compliance of all the assembled parts of the pore-water
checked to determine whether they have become clogged.
pressure-measurement system relative to the total volume of
the specimen, satisfying the following requirement: 5.13 Filter-Paper Strips and Disks— Filter-paper strips are
26 2 25 2 used by many laboratories to decrease the time required for
~∆V/V!/∆u,3.2 310 m /kN ~2.2 310 in. /lb! (1)
testing. Filter-paper disks of a diameter equal to that of the
where:
specimen may be placed between the porous disks and speci-
∆V = change in volume of the pore-water measurement
men to avoid clogging of the porous disks. If filter strips or
3 3
system due to a pore pressure change, mm (in. ),
disks are used, they shall be of a type that does not dissolve in
3 3
V = total volume of the specimen, mm (in. ), and
water. The coefficient of permeability of the filter paper shall
−5 −6
∆u = change in pore pressure, kPa (lbf/in. ).
not be less than 1×10 cm/s (4×10 in./s) for a normal
NOTE 6—To meet the compliance requirement, tubing between the
pressure of 550 kPa (80 lbf/in. ). To avoid hoop tension, filter
specimen and the measuring device should be short and thick-walled with
strips should cover no more than 50% of the specimen
small bores. Thermoplastic, copper, and stainless steel tubing have been
periphery. Filter-strip cages have been successfully used by
used successfully. To measure this compliance, assemble the triaxial cell
without a specimen. Then, open the appropriate valves, increase the many laboratories. An equation for correcting the principal
D4767 − 11 (2020)
stress difference (deviator stress) for the effect of the strength or by any other method that will satisfy the requirement for
of vertical filter strips is given in 10.4.3.1. saturating the specimen within the limits imposed by the
availablemaximumbackpressureandtimetoperformthetest.
NOTE 7—Grade No. 54 Filter Paper has been found to meet the
permeability and durability requirements.
5.21 Testing Environment—The consolidation and shear
portion of the test shall be performed in an environment where
5.14 Rubber Membrane—The rubber membrane used to
temperaturefluctuationsarelessthan 64°C(67.2°F)andthere
encase the specimen shall provide reliable protection against
is no direct contact with sunlight.
leakage. Membranes shall be carefully inspected prior to use
andifanyflawsorpinholesareevident,themembraneshallbe
5.22 Miscellaneous Apparatus—Specimen trimming and
discarded. To offer minimum restraint to the specimen, the
carving tools including a wire saw, steel straightedge, miter
unstretched membrane diameter shall be between 90 and 95%
box, vertical trimming lathe, apparatus for preparing reconsti-
of that of the specimen. The membrane thickness shall not
tuted specimens, membrane and O-ring expander, water con-
exceed 1% of the diameter of the specimen. The membrane
tent cans, and data sheets shall be provided as required.
shall be sealed to the specimen cap and base with rubber
O-ringsforwhichtheunstressedinsidediameterisbetween75
6. Test Specimen Preparation
and 85% of the diameter of the cap and base, or by other
6.1 Specimen Size—Specimensshallbecylindricalandhave
means that will provide a positive seal. An equation for
a minimum diameter of 33 mm (1.3 in.). The average height-
correcting the principal stress difference (deviator stress) for
to-average diameter ratio shall be between 2 and 2.5. The
the effect of the stiffness of the membrane is given in 10.4.3.2.
largest particle size shall be smaller than ⁄6 the specimen
5.15 Valves—Changesinvolumeduetoopeningandclosing
diameter. If, after completion of a test, it is found based on
valves may result in inaccurate volume change and pore-water
visual observation that oversize particles are present, indicate
pressuremeasurements.Forthisreason,valvesinthespecimen
this information in the report of test data (11.2.23).
drainage system shall be of the type that produce minimum
NOTE 10—If oversize particles are found in the specimen after testing,
volume changes due to their operation. A valve may be
a particle-size analysis may be performed on the tested specimen in
assumed to produce minimum volume change if opening or
accordance with Test Method D422 to confirm the visual observation and
closing the valve in a closed, saturated pore-water pressure
the results provided with the test report (11.2.4).
system does not induce a pressure change of greater than 0.7
2 6.2 Intact Specimens—Prepare intact specimens from large
kPa(60.1lbf/in. ).Allvalvesmustbecapableofwithstanding
intact samples or from samples secured in accordance with
applied pressures without leakage.
Practice D1587/D1587M or other acceptable intact tube sam-
NOTE 8—Ball valves have been found to provide minimum volume-
pling procedures. Samples shall be preserved and transported
change characteristics; however, any other type of valve having suitable
in accordance with the practices for Group C samples in
volume-change characteristics may be used.
Practices D4220/D4220M. Specimens obtained by tube sam-
5.16 Specimen-Size Measurement Devices—Devicesusedto
pling may be tested without trimming except for cutting the
determine the height and diameter of the specimen shall
endsurfacesplaneandperpendiculartothelongitudinalaxisof
measuretherespectivedimensionstofoursignificantdigitsand
the specimen, provided soil characteristics are such that no
shall be constructed such that their use will not disturb/deform
significant disturbance results from sampling. Handle speci-
the specimen.
mens carefully to minimize disturbance, changes in cross
section,orchangeinwatercontent.Ifcompressionoranytype
NOTE 9—Circumferential measuring tapes are recommended over
calipers for measuring the diameter. of noticeable disturbance would be caused by the extrusion
device, split the sample tube lengthwise or cut the tube in
5.17 Sample Extruder—The sample extruder shall be ca-
suitable sections to facilitate removal of the specimen with
pable of extruding the soil core from the sampling tube at a
minimum disturbance. Prepare trimmed specimens, in an
uniform rate in the same direction of travel as the sample
environment such as a controlled high-humidity room where
entered the tube and with minimum disturbance of the sample.
soil water content change is minimized. Where removal of
If the soil core is not extruded vertically, care should be taken
pebbles or crumbling resulting from trimming causes voids on
toavoidbendingstressesonthecoreduetogravity.Conditions
the surface of the specimen, carefully fill the voids with
at the time of sample removal may dictate the direction of
remolded soil obtained from the trimmings. If the sample can
removal,buttheprincipalconcernistominimizethedegreeof
betrimmedwithminimaldisturbance,averticaltrimminglathe
disturbance.
may be used to reduce the specimen to the required diameter.
5.18 Timer—A timing device indicating the elapsed testing
After obtaining the required diameter, place the specimen in a
timetothenearest1sshallbeusedtoobtainconsolidationdata
miter box, and cut the specimen to the final height with a wire
(8.3.3).
saw or other suitable device. Trim the surfaces with the steel
straightedge. Perform one or more water content determina-
5.19 Balance—A balance or scale conforming to the re-
quirements of Specification D4753 readable to four significant tions on material trimmed from the specimen in accordance
with Test Method D2216.
digits.
5.20 Water Deaeration Device—The amount of dissolved 6.3 Reconsituted Specimens—Soilrequiredforreconstituted
gas (air) in the water used to saturate the specimen shall be specimens shall be thoroughly mixed with sufficient water to
decreased by boiling, by heating and spraying into a vacuum, produce the desired water content. If water is added to the soil,
D4767 − 11 (2020)
thicknessoffilterdisksiftheyareused)sothattheappropriatevaluesmay
store the material in a covered container for at least 16 h prior
be subtracted from the measurements.
to compaction. Reconsituted specimens may be prepared by
compacting material in at least six layers using a split mold of
7.2.1 Wet Mounting Method:
circular cross section having dimensions meeting the require-
7.2.1.1 Fill the specimen drainage lines and the pore-water
ments enumerated in 6.1. Specimens may be reconstituted to
pressure measurement device with deaired water.
the desired density by either: (1) kneading or tamping each
7.2.1.2 Saturate the porous disks by boiling them in water
layeruntiltheaccumulativemassofthesoilplacedinthemold
for at least 10 min and allow to cool to room temperature.
is reconstituted to a known volume; or (2) by adjusting the
7.2.1.3 If filter-paper disks are to be placed between the
number of layers, the number of tamps per layer, and the force
porous disks and specimen, saturate the paper with water prior
per tamp. The top of each layer shall be scarified prior to the
to placement.
addition of material for the next layer. The tamper used to
7.2.1.4 Place a saturated porous disk on the specimen base
compactthematerialshallhaveadiameterequaltoorlessthan
and wipe away all free water on the disk. If filter-paper disks
⁄2 the diameter of the mold.After a specimen is formed, with
are used, placed on the porous disk. Place the specimen on the
the ends perpendicular to the longitudinal axis, remove the
disk.Next,placeanotherfilter-paperdisk(ifused),porousdisk
mold and determine the mass and dimensions of the specimen
and the specimen cap on top of the specimen. Check that the
using the devices described in 5.16 and 5.19. Perform one or
specimencap,specimen,filter-paperdisks(ifused)andporous
more water content determinations on excess material used to
disks are centered on the specimen base.
prepare the specimen in accordance with Test Method D2216.
7.2.1.5 If filter-paper strips or a filter-paper cage are to be
6.4 Determine the mass and dimensions of the specimen
used, saturate the paper with water prior to placing it on the
using the devices described in 5.16 and 5.19. A minimum of
specimen.Toavoidhooptension,donotcovermorethan50%
three height measurements (120° apart) and at least three
of the specimen periphery with vertical strips of filter paper.
diameter measurements at the quarter points of the height shall
7.2.1.6 Proceed with 7.3.
be made to determine the average height and diameter of the
specimen. An individual measurement of height or diameter
7.2.2 Dry Mounting Method:
shall not vary from average by more than 5%.
7.2.2.1 Dry the specimen drainage system. This may be
NOTE 11—It is common for the density or unit weight of the specimen
accomplished by allowing dry air to flow through the system
afterremovalfromthemoldtobelessthanthevaluebasedonthevolume
prior to mounting the specimen.
ofthemold.Thisoccursasaresultofthespecimenswellingafterremoval
of the lateral confinement due to the mold. 7.2.2.2 Dry the porous disks in an oven and then place the
disks in a desiccator to cool to room temperature prior to
7. Mounting Specimen
mounting the specimen.
7.2.2.3 Place a dry porous disk on the specimen base and
7.1 Preparations—Before mounting the specimen in the
place the specimen on the disk. Next, place a dry porous disk
triaxial chamber, make the following preparations:
and the specimen cap on the specimen. Check that the
7.1.1 Inspect the rubber membrane for flaws, pinholes, and
specimen cap, porous disks, and specimen are centered on the
leaks.
specimen base.
7.1.2 Place the membrane on the membrane expander or, if
it is to be rolled onto the specimen, roll the membrane on the
NOTE 13—If desired, dry filter-paper disks may be placed between the
cap or base.
porous disks and specimen.
7.1.3 Check that the porous disks and specimen drainage
7.2.2.4 If filter-paper strips or a filter-paper cage are to be
tubes are not obstructed by passing air or water through the
used,thecageorstripsmaybeheldinplacebysmallpiecesof
appropriate lines.
tape at the top and bottom.
7.1.4 Attach the pressure-control and volume-measurement
system and a pore-pressure measurement device to the cham-
7.3 Place the rubber membrane around the specimen and
ber base.
seal it at the cap and base with two rubber O-rings or other
positivesealateachend.Athincoatingofsilicongreaseonthe
7.2 Depending on whether the saturation portion of the test
vertical surfaces of the cap and base will aid in sealing the
will be initiated with either a wet or dry drainage system,
membrane. If filter-paper strips or a filter-paper cage are used,
mount the specimen using the appropriate method, as follows
do not apply grease to surfaces in contact with the filter-paper.
in either 7.2.1 or 7.2.2. The dry mounting method is strongly
recommended for specimens with initial saturation less than
7.4 Attach the top drainage line and check the alignment of
90%. The dry mounting method removes air prior to adding
the specimen and the specimen cap. If the dry mounting
backpressure and lowers the backpressure needed to attain an
method has been used, apply a partial vacuum of approxi-
adequate percent saturation. 2
mately 35 kPa (5 lbf/in. ) (not to exceed the consolidation
NOTE12—Itisrecommendedthatthedrymountingmethodbeusedfor stress) to the specimen through the top drainage line prior to
specimens of soils that swell appreciably when in contact with water. If
checking the alignment. If there is any eccentricity, release the
the wet mounting method is used for such soils, it will be necessary to
partialvacuum,realignthespecimenandcap,andthenreapply
obtain the specimen dimensions after the specimen has been mounted. In
thepartialvacuum.Ifthewetmountingmethodhasbeenused,
such cases, it will be necessary to determine the double thickness of the
the alignment of the specimen and the specimen cap may be
membrane,thedoublethicknessofthewetfilterpaperstrips(ifused),and
the combined height of the cap, base, and porous disks (including the checked and adjusted without the use of a partial vacuum.
D4767 − 11 (2020)
8. Procedure between the pore pressure measured at the bottom of the
specimenandthepressureatthetopofthespecimenshouldbe
8.1 Prior to Saturation—After assembling the triaxial
allowed to equalize. When the pore pressure at the bottom of
chamber, perform the following operations:
the specimen stabilizes, proceed with back pressuring of the
8.1.1 Bring the axial load piston into contact with the
specimen pore-water as described in 8.2.3.1. To check for
specimen cap several times to permit proper seating and
equalization, close the drainage valves to the specimen and
alignment of the piston with the cap. During this procedure,
measure the pore pressure change until stable. If the change is
take care not to apply an axial load to the specimen exceeding
less than 5% of the chamber pressure, the pore pressure may
0.5% of the estimated axial load at failure. When the piston is
be assumed to be stabilized.
brought into contact, record the reading of the deformation
indicator to three significant digits.
NOTE 14—For saturated clays, percolation may not be necessary and
water can be added simultaneously at both top and bottom.
8.1.2 Fill the chamber with the chamber liquid, being
careful to avoid trapping air or leaving an air space in the
8.2.2 Starting with Initially Saturated Drainage System—
chamber.
After filling the burette connected to the top of the specimen
with deaired water, apply a chamber pressure of 35 kPa (5
8.2 Saturation—The objective of the saturation phase of the
lbf/in. ) or less and open the specimen drainage valves. When
test is to fil
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