1、Designation:D476704 Designation: D4767 11Standard Test Method forConsolidated Undrained Triaxial Compression Test forCohesive Soils1This standard is issued under the fixed designation D4767; the number immediately following the designation indicates the year oforiginal adoption or, in the case of re
2、vision, the year of last revision. A number in parentheses indicates the year of last reapproval. Asuperscript epsilon () indicates an editorial change since the last revision or reapproval.1. Scope*1.1 This test method covers the determination of strength and stress-strain relationships of a cylind
3、rical specimen of either anundisturbedintact, reconstituted, or remolded saturated cohesive soil. Specimens are isotropically consolidated and sheared incompression without drainage at a constant rate of axial deformation (strain controlled).1.2 This test method provides for the calculation of total
4、 and effective stresses, and axial compression by measurement of axialload, 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 Mohrstrength envelopes and Youngs modulus. Generally, three sp
5、ecimens are tested at different effective consolidation stresses todefine a strength envelope.1.4 The determination of strength envelopes and the development of relationships to aid in interpreting and evaluating testresults are beyond the scope of this test method and must be performed by a qualifi
6、ed, experienced professional.1.5All1.5 All observed and calculated values shall conform to the guidelines for significant digits and rounding established inPractice D6026.1.5.1The method used to specify how data are collected, calculated, or recorded in this standard is not directly related to theac
7、curacy to which the data can be applied in design or other uses, or both. How one applies the results obtained using this standardis beyond its scope.1.6The values stated in SI units shall be regarded as the standard. The values stated in inch-pound units are approximate.1.5.1 The methods used to sp
8、ecify how data are collected, calculated, or recorded in this standard are regarded as the industrystandard. In addition, they are representative of the significant digits that generally should be retained. The procedures used do notconsider material variation, purpose for obtaining the data, specia
9、l purpose studies or any consideration of end use. It is beyondthe scope of this test method to consider significant digits used in analysis methods for engineering design.1.6 UnitsThe values stated in SI units are to be regarded as standard. The inch-pound units given in parentheses aremathematical
10、 conversions which are provided for information purposes only and are not considered standard. Reporting of testresults in units other than SI shall not be regarded as nonconformance with this test method.1.6.1 The gravitational system of inch-pound units is used when dealing with inch-pound units.
11、In this system, the pound (lbf)represents a unit of force (weight), while the unit for mass is slugs. The slug unit is not given, unless dynamic (F = ma) calculationsare involved.1.6.2 It is common practice in the engineering/construction profession to concurrently use pounds to represent both a uni
12、t ofmass (lbm) and of force (lbf). This implicitly combines two separate systems of units; that is, the absolute system and thegravitational system. It is scientifically undesirable to combine the use of two separate sets of inch-pound units within a singlestandard. As stated, this standard includes
13、 the gravitational system of inch-pound units and does not use/present the slug unit formass. However, the use of balances or scales recording pounds of mass (lbm) or recording density in lbm/ft3shall not be regardedas nonconformance with this standard.1.6.3 The terms density and unit weight are oft
14、en used interchangeably. Density is mass per unit volume whereas unit weightis force per unit volume. In this standard density is given only in SI units. After the density has been determined, the unit weightis calculated in SI or inch-pound units, or both.1.7 This standard does not purport to addre
15、ss all of the safety concerns, if any, associated with its use. It is the responsibility1This test method is under the jurisdiction of ASTM Committee D18 on Soil and Rock and is the direct responsibility of Subcommittee D18.05 on Strength andCompressibility of Soils.Current edition approved Nov. 1,
16、2004. Published December 2004. Originally approved in 1988. Last previou edition approved in 2002 as D476702. DOI:10.1520/D4767-04.Current edition approved Jan. 15, 2011. Published February 2011. Originally approved in 1988. Last previou edition approved in 2004 as D476704. DOI:10.1520/D4767-11.1Thi
17、s document is not an ASTM standard and is intended only to provide the user of an ASTM standard an indication of what changes have been made to the previous version. Becauseit may not be technically possible to adequately depict all changes accurately, ASTM recommends that users consult prior editio
18、ns as appropriate. In all cases only the current versionof the standard as published by ASTM is to be considered the official document.*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,
19、 United States.of the user of this standard to establish appropriate safety and health practices and determine the applicability of regulatorylimitations prior to use.2. Referenced Documents2.1 ASTM Standards:2D422 Test Method for Particle-Size Analysis of SoilsD653 Terminology Relating to Soil, Roc
20、k, and Contained FluidsD854 Test Methods for Specific Gravity of Soil Solids by Water PycnometerD1587 Practice for Thin-Walled Tube Sampling of Soils for Geotechnical PurposesD2166 Test Method for Unconfined Compressive Strength of Cohesive SoilD2216 Test Methods for Laboratory Determination of Wate
21、r (Moisture) Content of Soil and Rock by MassD2435 Test Methods for One-Dimensional Consolidation Properties of Soils Using Incremental LoadingD2850 Test Method for Unconsolidated-Undrained Triaxial Compression Test on Cohesive SoilsD3740 Practice for Minimum Requirements for Agencies Engaged in Tes
22、ting and/or Inspection of Soil and Rock as Used inEngineering Design and ConstructionD4220 Practices for Preserving and Transporting Soil SamplesD4318 Test Methods for Liquid Limit, Plastic Limit, and Plasticity Index of SoilsD4753 Guide for Evaluating, Selecting, and Specifying Balances and Standar
23、d Masses for Use in Soil, Rock, and ConstructionMaterials TestingD6026 Practice for Using Significant Digits in Geotechnical Data3. Terminology3.1 DefinitionsThe definitions of terms used in this test method shall be in accordance with Terminology For standarddefinitions of common technical terms, r
24、efer to Terminology D653.3.2 Definitions of Terms Specific to This Standard:3.2.1 back pressurea pressure applied to the specimen pore-water to cause air in the pore space to compress and to pass intosolution in the pore-water thereby increasing the percent saturation of the specimen.3.2.2 effective
25、 consolidation stressthe difference between the cell pressure and the pore-water pressure prior to shearing thespecimen.3.2.3 failurethe stressa maximum-stress condition or stress at failure a defined strain for a test specimen. Failure is oftentaken to correspond to the maximum principal stress dif
26、ference (maximum deviator stress) attained or the principal stress difference(deviator stress) at 15 % axial strain, whichever is obtained first during the performance of a test. Depending on soil behavior andfield application, other suitable failure criteria may be defined, such as maximum effectiv
27、e stress obliquity, s81/s83,(s18/s38)max,or the principal stress difference (deviator stress) at a selected axial strain other than 15 %.4. Significance and Use4.1 The shear strength of a saturated soil in triaxial compression depends on the stresses applied, time of consolidation, strainrate, and t
28、he 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 conditionswhere soils that have been fully consolidated under one set of stresses are subjected to a change in stress without time for furth
29、erconsolidation to take place (undrained condition), and the field stress conditions are similar to those in the test method.NOTE 1If the strength is required for the case where the soil is not consolidated during testing prior to shear, refer to Test Method D2850 or TestMethod D2166.4.3 Using the p
30、ore-water pressure measured during the test, the shear strength determined from this test method can beexpressed in terms of effective stress. This shear strength may be applied to field conditions where full drainage can occur (drainedconditions) or where pore pressures induced by loading can be es
31、timated, and the field stress conditions are similar to those in thetest 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 calc
32、ulations, and foundation design.NOTE 2Notwithstanding the statements on precision and bias contained in this test method. The precision of this test method is dependent on thecompetence of the personnel performing it and the suitability of the equipment and facilities used. Agencies which meet the c
33、riteria of Practice D3740are generally considered capable of competent testing. Users of this test method are cautioned that compliance with Practice D3740 does not ensurereliable testing. Reliable testing depends on several factors; Practice D3740 provides a means of evaluating some of those factor
34、s.5. Apparatus5.1 The requirements for equipment needed to perform satisfactory tests are given in the following sections. See Fig. 1 and Fig.22For referencedASTM standards, visit theASTM website, www.astm.org, or contactASTM Customer Service at serviceastm.org. For Annual Book of ASTM Standardsvolu
35、me information, refer to the standards Document Summary page on the ASTM website.D4767 1125.2 Axial Loading DeviceThe axial loading device shall be a screw jack driven by an electric motor through a gearedtransmission, a hydraulic loading device, or any other compression device with sufficient capac
36、ity and control to provide the rateof axial strain (loading) prescribed in 8.4.2. The rate of advance of the loading device shall not deviate by more than 61 % fromthe selected value. Vibration due to the operation of the loading device shall be sufficiently small to not cause dimensional changesin
37、the specimen or to produce changes in pore-water pressure when the drainage valves are closed.NOTE 3Aloading device may be judged to produce sufficiently small vibrations if there are no visible ripples in a glass of water placed on the loadingplatform when the device is operating at the speed at wh
38、ich the test is performed.5.3 Axial Load-Measuring DeviceThe axial load-measuring device shall be a load ring,an electronic load cell, hydraulic loadcell, or any other load-measuring device capable of the accuracy prescribed in this paragraph and may be a part of the axial loadingFIG. 1 Schematic Di
39、agram of a Typical Consolidated Undrained Triaxial ApparatusFIG. 2 Filter Strip CageD4767 113device. The axial load-measuring device shall be capable of measuring the axial load to an accuracy of within 1 % of the axial loadat failure. If the load-measuring device is located inside the triaxial comp
40、ression chamber, it shall be insensitive to horizontal forcesand to the magnitude of the chamber pressure.5.4 Triaxial Compression ChamberThe triaxial chamber shall have a working chamber pressure equal to the sum of theeffective consolidation stress and the back pressure. It shall consist of a top
41、plate and a base plate separated by a cylinder. Thecylinder may be constructed of any material capable of withstanding the applied pressures. It is desirable to use a transparentmaterial or have a cylinder provided with viewing ports so the behavior of the specimen may be observed. The top plate sha
42、ll havea vent valve such that air can be forced out of the chamber as it is filled. The baseplate shall have an inlet through which thepressure liquid is supplied to fill the chamber, and inlets leading to the specimen base and to the cap to allow saturation anddrainage of the specimen when required
43、. The chamber shall provide a connection to the cap.5.5 Axial Load PistonThe piston passing through the top of the chamber and its seal must be designed so the variation in axialload due to friction does not exceed 0.1 % of the axial load at failure and so there is negligible lateral bending of the
44、piston duringloading.NOTE 4The use of two linear ball bushings to guide the piston is recommended to minimize friction and maintain alignment.NOTE 5A minimum piston diameter of16 the specimen diameter has been used successfully in many laboratories to minimize lateral bending.5.6 Pressure and Vacuum
45、-Control DevicesThe chamber pressure and back pressure control devices shall be capable ofapplying and controlling pressures to within 62 kPa (0.25 lb/in.2) for effective consolidation pressures less than 200 kPa (28lbf/in.2) and to within 61 % for effective consolidation pressures greater than 200
46、kPa. The vacuum-control device shall be capableof applying and controlling partial vacuums to within 62 kPa. The devices shall consist of pressure/volume controllers,self-compensating mercury pots,controllers pneumatic pressure regulators, combination pneumatic pressure and vacuumregulators, or any
47、other device capable of applying and controlling pressures or partial vacuums to the required tolerances. Thesetests can require a test duration of several day. Therefore, an air/water interface is not recommended for either the chamber pressureor back pressure systems, unless isolated from the spec
48、imen and chamber (e.g. by long tubing).5.7 Pressure- and Vacuum-Measurement DevicesThe chamber pressure-, back pressure-, and vacuum-measuring devicesshall be capable of measuring pressures or partial vacuums to the tolerances given in 5.6. They may consist of Bourdon gages,pressure manometers, elec
49、tronic pressure transducers, or any other device capable of measuring pressures, or partial vacuums tothe stated tolerances. If separate devices are used to measure the chamber pressure and back pressure, the devices must becalibrated simultaneously and against the same pressure source. Since the chamber and back pressure are the pressures taken atthe mid-height of the specimen, it may be necessary to adjust the calibration of the devices to reflect the hydraulic head of fluidsin the chamber and back pressure control systems.5.8 Pore-Water Pressure-Measurement
