1、Designation: D3999 11Standard Test Methods forthe Determination of the Modulus and Damping Propertiesof Soils Using the Cyclic Triaxial Apparatus1This standard is issued under the fixed designation D3999; the number immediately following the designation indicates the year oforiginal adoption or, in
2、the case of revision, 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 These test methods cover the determination of themodulus and damping properties of
3、soils in either intact orreconstituted states by either load or stroke controlled cyclictriaxial techniques. The standard is focused on determiningthese properties for soils in hydrostatically consolidated,undrained conditions.1.2 The cyclic triaxial properties of initially saturated orunsaturated s
4、oil specimens are evaluated relative to a numberof factors including: strain level, density, number of cycles,material type, and effective stress.1.3 These test methods are applicable to both fine-grainedand coarse-grained soils as defined by the unified soil classi-fication system or by Classificat
5、ion D2487. Test specimensmay be intact or reconstituted by compaction in the laboratory.1.4 Two test methods are provided for using a cyclic loaderto determine the secant Youngs modulus (E) and dampingcoefficient (D) for a soil specimen. The first test method (A)permits the determination of E and D
6、using a constant loadapparatus. The second test method (B) permits the determina-tion of E and D using a constant stroke apparatus. The testmethods are as follows:1.4.1 Test Method AThis test method requires the appli-cation of a constant cyclic load to the test specimen. It is usedfor determining t
7、he secant Youngs modulus and dampingcoefficient under a constant load condition.1.4.2 Test Method BThis test method requires the appli-cation of a constant cyclic deformation to the test specimen. Itis used for determining the secant Youngs modulus anddamping coefficient under a constant stroke cond
8、ition.1.5 The development of relationships to aid in interpretingand evaluating test results are left to the engineer or officerequesting the test.1.6 LimitationsThere are certain limitations inherent inusing cyclic triaxial tests to simulate the stress and strainconditions of a soil element in the
9、field during an earthquake,with several summarized in the following sections. With dueconsideration for the factors affecting test results, carefullyconducted cyclic triaxial tests can provide data on the cyclicbehavior of soils with a degree of accuracy adequate formeaningful evaluations of modulus
10、 and damping coefficientbelow a shearing strain level of 0.5 %.1.6.1 Nonuniform stress conditions within the test specimenare imposed by the specimen end platens.1.6.2 A 90 change in the direction of the major principalstress occurs during the two halves of the loading cycle onisotropically confined
11、 specimens.1.6.3 The maximum cyclic axial stress that can be applied toa saturated specimen is controlled by the stress conditions atthe end of confining stress application and the pore-waterpressures generated during undrained compression. For anisotropically confined specimen tested in cyclic comp
12、ression,the maximum cyclic axial stress that can be applied to thespecimen is equal to the effective confining pressure. Sincecohesionless soils cannot resist tension, cyclic axial stressesgreater than this value tend to lift the top platen from the soilspecimen. Also, as the pore-water pressure inc
13、reases duringtests performed on isotropically confined specimens, the effec-tive confining pressure is reduced, contributing to the tendencyof the specimen to neck during the extension portion of theload cycle, invalidating test results beyond that point.1.6.4 While it is advised that the best possi
14、ble intactspecimens be obtained for cyclic testing, it is sometimesnecessary to reconstitute soil specimens. It has been shown thatdifferent methods of reconstituting specimens to the samedensity may result in significantly different cyclic behavior.Also, intact specimens will almost always be stron
15、ger andstiffer than reconstituted specimens of the same density.1.6.5 The interaction between the specimen, membrane, andconfining fluid has an influence on cyclic behavior. Membranecompliance effects cannot be readily accounted for in the testprocedure or in interpretation of test results. Changes
16、inpore-water pressure can cause changes in membrane penetra-tion in specimens of cohesionless soils. These changes cansignificantly influence the test results.1.7 The values stated in either SI units or inch-pound unitspresented in brackets are to be regarded separately asstandard. The values stated
17、 in each system may not be exact1These test methods are under the jurisdiction ofASTM Committee D18 on Soiland Rock and are the direct responsibility of Subcommittee D18.09 on Cyclic andDynamic Properties of Soils.Current edition approved Nov. 1, 2011. Published January 2012. Originallyapproved in 1
18、991. Last previous edition approved in 2003 as D399991(2003).DOI: 10.1520/D3999-11.1*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.equivalents; therefore, each system
19、shall be used independentlyof the other. Combining values from the two systems mayresult in non-conformance with the standard. Reporting of testresults in units other than SI shall not be regarded as noncon-formance with this test method.1.8 All observed and calculated values shall conform to thegui
20、de for significant digits and rounding established in PracticeD6026. The procedures in Practice D6026 that are used tospecify how data are collected, recorded, and calculated areregarded as the industry standard. In addition, they are repre-sentative of the significant digits that should generally b
21、eretained. The procedures do not consider material variation,purpose for obtaining the data, special purpose studies, or anyconsiderations for the objectives of the user. Increasing orreducing the significant digits of reported data to be commen-surate with these considerations is common practice. C
22、onsid-eration of the significant digits to be used in analysis methodsfor engineering design is beyond the scope of this standard.1.8.1 The method used to specify how data are collected,calculated, or recorded in this standard is not directly related tothe accuracy to which the data can be applied i
23、n design or otheruses, or both. How one applies the results obtained using thisstandard is beyond its scope.1.9 This standard does not purport to address all of thesafety concerns, if any, associated with its use. It is theresponsibility of the user of this standard to establish appro-priate safety
24、and health practices and determine the applica-bility of regulatory limitations prior to use.2. Referenced Documents2.1 ASTM Standards:2D422 Test Method for Particle-Size Analysis of SoilsD653 Terminology Relating to Soil, Rock, and ContainedFluidsD854 Test Methods for Specific Gravity of Soil Solid
25、s byWater PycnometerD1587 Practice for Thin-Walled Tube Sampling of Soils forGeotechnical PurposesD2216 Test Methods for Laboratory Determination of Wa-ter (Moisture) Content of Soil and Rock by MassD2435 Test Methods for One-Dimensional ConsolidationProperties of Soils Using Incremental LoadingD248
26、7 Practice for Classification of Soils for EngineeringPurposes (Unified Soil Classification System)D2488 Practice for Description and Identification of Soils(Visual-Manual Procedure)D3740 Practice for Minimum Requirements for AgenciesEngaged in Testing and/or Inspection of Soil and Rock asUsed in En
27、gineering Design and ConstructionD4220 Practices for Preserving and Transporting SoilSamplesD4318 Test Methods for Liquid Limit, Plastic Limit, andPlasticity Index of SoilsD4767 Test Method for Consolidated Undrained TriaxialCompression Test for Cohesive SoilsD6026 Practice for Using Significant Dig
28、its in GeotechnicalData2.2 USBR Standard:USBR 5210 Practice for Preparing Compacted Soil Speci-mens for Laboratory Use33. Terminology3.1 Definitions:3.1.1 The definitions of terms used in these test methodsshall be in accordance with Terminology D653.3.1.2 back pressurea pressure applied to the spec
29、imenpore-water to cause air in the pore space to pass into solutionin the pore-water, that is, to saturate the specimen.3.2 Definitions of Terms Specific to This Standard:3.2.1 cycle durationthe time interval between successiveapplications of a deviator stress.3.2.2 deviator stress FL2the difference
30、 between themajor and minor principal stresses in a triaxial test.3.2.3 effective confining stressthe confining pressure (thedifference between the cell pressure and the pore-water pres-sure) prior to shearing the specimen.3.2.4 effective force, (F)the force transmitted through asoil or rock mass by
31、 intergranular pressures.3.2.5 hysteresis loopa trace of load versus deformationresulting from the application of one complete cycle of eithera cyclic load or deformation. The area within the resulting loopis due to energy dissipated by the specimen and apparatus, seeFig. 1.3.2.6 load durationthe ti
32、me interval the specimen issubjected to a cyclic deviator stress.4. Summary of Test Method4.1 The cyclic triaxial test consists of imposing either acyclic axial deviator stress of fixed magnitude (load control) orcyclic axial deformation (stroke control) on a cylindrical,hydrostatically consolidated
33、 soil specimen in undrained condi-tions. The resulting axial strain and axial stress are measured2Annual Book of ASTM Standards, Vol 04.08.3Available from U.S. Department of the Interior, Bureau of Reclamation.FIG. 1 Schematic of Typical Hysteresis Loop Generated by CyclicTriaxial ApparatusD3999 112
34、and used to calculate either stress-dependent or stroke-dependent secant modulus and damping coefficient.5. Significance and Use5.1 The cyclic triaxial test permits determination of thesecant modulus and damping coefficient for cyclic axial load-ing of a prismatic soil specimen in hydrostatically co
35、nsoli-dated, undrained conditions. The secant modulus and dampingcoefficient from this test may be different from those obtainedfrom a torsional shear type of test on the same material.5.2 The secant modulus and damping coefficient are impor-tant parameters used in dynamic, performance evaluation of
36、both natural and engineered structures under dynamic or cyclicloads such as caused by earthquakes, ocean wave, or blasts.These parameters can be used in dynamic response analysesincluding, finite elements, finite difference, and linear ornon-linear analytical methods.NOTE 1The quality of the result
37、produced by this standard isdependent on the competence of the personnel performing it, and thesuitability of the equipment and facilities used. Agencies that meet thecriteria of Practice D3740 are generally considered capable of competentand objective testing/sampling/inspection/etc. Users of this
38、standard arecautioned that compliance with Practice D3740 does not in itself assurereliable results. Reliable results depend on many factors; Practice D3740provides a means of evaluating some of those factors.6. Apparatus6.1 GeneralIn many ways, triaxial equipment suitable forcyclic triaxial tests i
39、s similar to equipment used for theconsolidated-undrained triaxial compression test (see TestMethod D4767). However, there are special features describedin the following sections that are required to perform accept-able cyclic triaxial tests. A schematic representation of thevarious components compr
40、ising a cyclic triaxial test setup isshown in Fig. 2.6.2 Cyclic Loading Equipment:6.2.1 Cyclic loading equipment used for load controlledcyclic triaxial tests must be capable of applying a uniformsinusoidal load at a frequency within the range of 0.1 to 2 Hz.6.2.2 The equipment must be able to apply
41、 the cyclic loadabout an initial static load on the loading piston.6.2.3 The loading device must be able to maintain uniformcyclic loadings to at least 0.5 % of the double amplitude stress,as defined in Fig. 3. The loading pattern used in this standardshall be harmonic, as shown in Fig. 4(a). Unacce
42、ptable loadingpatterns, such as unsymmetrical compression-extension loadpeaks, nonuniformity of pulse duration, “ringing,” or loadfall-off at large strains are illustrated in Fig. 4(b) to Fig. 4(f).The loading pattern shall be compared to the tolerances shownin Fig. 4 to evaluate if it is acceptable
43、 for use in this standard.6.2.4 Cyclic loading equipment used for deformation-controlled cyclic triaxial tests must be capable of applying auniform sinusoidal deformation at a frequency range of 0.1 to2 Hz. The equipment must also be able to apply the cyclicdeformation about either an initial datum
44、point or follow thespecimen as it deforms. The type of apparatus typicallyemployed can range from a simple cam to a closed loopelectro-hydraulic system.6.3 Triaxial Pressure CellThe primary considerations inselecting the cell are tolerances for the piston, top platen, andlow friction piston seal, as
45、 summarized in Fig. 5.6.3.1 Two linear ball bushings or similar bearings should beused to guide the loading piston to minimize friction and tomaintain alignment.6.3.2 The loading piston diameter should be large enough tominimize lateral bending. A minimum loading piston diameterof16 the specimen dia
46、meter has been used successfully inmany laboratories.FIG. 2 Schematic Representation of Load or Stroke-Controlled Cyclic Triaxial Test SetupD3999 1136.3.3 The loading piston seal is a critical element in triaxialcell design for cyclic soils testing if an external load cellconnected to the loading ro
47、d is employed. The seal must exertnegligible friction on the loading piston. The maximum accept-able piston friction tolerable without applying load correctionsis commonly considered to be 62 % of the maximum singleamplitude cyclic load applied in the test, refer to Fig. 3.The useof a seal described
48、 in 6.4.8 and by Ladd and Dutko,4and Chan5will meet these requirements.6.3.4 Top and bottom platen alignment is critical to avoidincreasing a nonuniform state of stress in the specimen.Internal tie-rod triaxial cells have worked well at a number oflaboratories. These cells allow the placement of the
49、 cell wallafter the specimen is in place between the loading platens.Acceptable limits on platen eccentricity and parallelism areshown in Fig. 6.6.3.5 Since axial loading in cyclic triaxial tests is in exten-sion as well as in compression, the loading piston shall berigidly connected to the top platen by a method such as one ofthose shown in Fig. 7.6.3.6 There shall be provision for specimen drainage at boththe top and bottom platens for saturation and consolidation ofthe specimen before cyclic loading.6.4 System Compliance:6.4.1 SystemThe compliance of the lo
copyright@ 2008-2019 麦多课文库（www.mydoc123.com）网站版权所有
备案/许可证编号：苏ICP备17064731号-1