ASTM_D_3999_-_D_3999M_-_11e1.pdf

Designation:D3999/D3999M111Standard Test Methods forthe Determination of the Modulus and Damping Propertiesof Soils Using the Cyclic Triaxial Apparatus1This standard is issued under the fixed designation D3999/D3999M;the number immediately following the designation indicates theyear of original adoption or,in the case of revision,the year of last revision.A number in parentheses indicates the year of lastreapproval.A superscript epsilon()indicates an editorial change since the last revision or reapproval.1NOTEDesignation was editorially corrected to match units information in October 2013.1.Scope*1.1 These test methods cover the determination of themodulus and damping properties of 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 soil 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 Practice D2487.Test specimens may beintact 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 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 the 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 condition.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 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 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 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 compression,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 increases 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 possible 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 stronger 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 in1These 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 1991.Last previous edition approved in 2003 as D399991(2003).DOI:10.1520/D3999-11E01.*A Summary of Changes section appears at the end of this standardCopyright ASTM International,100 Bar