1、Designation: D 3999 91 (Reapproved 2003)Standard Test Methods forthe Determination of the Modulus and Damping Propertiesof Soils Using the Cyclic Triaxial Apparatus1This standard is issued under the fixed designation D 3999; the number immediately following the designation indicates the year oforigi
2、nal adoption or, in the case of revision, the year of last revision. A number in parentheses indicates the year of last reapproval. Asuperscript epsilon (e) indicates an editorial change since the last revision or reapproval.1. Scope1.1 These test methods cover the determination of themodulus and da
3、mping properties of soils in either undisturbedor reconstituted states by either load or stroke controlled cyclictriaxial techniques.1.2 The cyclic triaxial properties of soil are evaluatedrelative to a number of factors including: strain level, density,number of cycles, material type, saturation, a
4、nd 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 Classification D 2487. Test specimensmay be undisturbed or reconstituted by compaction in thelaboratory.1.4 Two test methods are provided
5、 for using a cyclic loaderto determine Youngs modulus (E) and damping (D) properties.The first test method (A) permits the determination of E and Dusing a constant load apparatus. The second test method (B)permits the determination of E and D using a constant strokeapparatus. The test methods are as
6、 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 Youngs modulus and damping under aconstant load condition.1.4.2 Test Method BThis test method requires the appli-cation of a constant cyclic deformatio
7、n to the test specimen. Itis used for determining the Youngs modulus and dampingunder 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
8、inherent inusing cyclic triaxial tests to simulate the stress and strainconditions of a soil element in the field during an earthquake.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 oc
9、curs during the two halves of the loading cycle onisotropically confined specimens and at certain levels of cyclicstress application on anisotropically 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
10、 of confining stress application and the pore-waterpressures generated during testing. For an isotropically con-fined specimen tested in cyclic compression, the maximumcyclic axial stress that can be applied to the specimen is equalto the effective confining pressure. Since cohesionless soils arenot
11、 capable of taking tension, cyclic axial stresses greater thanthis value tend to lift the top platen from the soil specimen.Also, as the pore-water pressure increases during tests per-formed on isotropically confined specimens, the effectiveconfining pressure is reduced, contributing to the tendency
12、 ofthe specimen to neck during the extension portion of the loadcycle, invalidating test results beyond that point.1.6.4 While it is advised that the best possible undisturbedspecimens be obtained for cyclic testing, it is sometimesnecessary to reconstitute soil specimens. It has been shown thatdiff
13、erent methods of reconstituting specimens to the samedensity may result in significantly different cyclic behavior.Also, undisturbed specimens will almost always be strongerthan reconstituted specimens of the same density.1.6.5 The interaction between the specimen, membrane, andconfining fluid has a
14、n influence on cyclic behavior. Membranecompliance effects cannot be readily accounted for in the testprocedure or in interpretation of test results. Changes inpore-water pressure can cause changes in membrane penetra-tion in specimens of cohesionless soils. These changes cansignificantly influence
15、the test results.1.6.6 Despite these limitations, with due consideration forthe factors affecting test results, carefully conducted cyclictriaxial tests can provide data on the cyclic behavior of soilswith a degree of accuracy adequate for meaningful evaluationsof modulus and damping below a shearin
16、g strain level of0.5 %.1These test methods are under the jurisdiction of ASTM Committee D18 on Soiland Rock and are the direct responsibility of Subcommittee D18.09 on DynamicProperties of Soils.Current edition approved August 15, 1991. Published October 1991.1Copyright ASTM International, 100 Barr
17、Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.1.7 The values stated in either SI or inch-pound units shallbe regarded separately as standard. The values in each systemmay not be exact equivalents, therefore, each system must beused independently of the other, without com
18、bining values inany way.1.8 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 and health practices and determine the applica-bility of regulatory limitations prio
19、r to use.2. Referenced Documents2.1 ASTM Standards:D 422 Test Method for Particle-Size Analysis of Soils2D 653 Terminology Relating to Soil, Rock, and ContainedFluids2D 854 Test Method for Specific Gravity of Soils2D 1587 Practice for Thin-Walled Tube Sampling of Soils2D 2216 Test Method for Laborat
20、ory Determination of Water(Moisture) Content of Soil and Rock2D 2435 Test Method for One-Dimensional ConsolidationProperties of Soils2D 2487 Classification of Soils for Engineering Purposes(Unified Soil Classification System)2D 2488 Practice for Description and Identification of Soils(Visual-Manual
21、Procedure)2D 3740 Practice for Minimum Requirements for AgenciesEngaged in the Testing and/or Inspection of Soil and Rockas Used in Engineering Design and Construction2D 4220 Practice for Preserving and Transporting SoilSamples2D 4318 Test Method for Liquid Limit, Plastic Limit, andPlasticity Index
22、of Soils2D 4767 Test Method for Consolidated-Undrained TriaxialCompression Test on Cohesive Soils22.2 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 accorda
23、nce with Terminology D 653.3.2 Definitions of Terms Specific to This Standard:3.2.1 back pressurea pressure applied to the specimenpore-water to cause air in the pore space to pass into solutionin the pore-water, that is, to saturate the specimen.3.2.2 cycle durationthe time interval between success
24、iveapplications of a deviator stress.3.2.3 deviator stress FL2the difference between themajor and minor principal stresses in a triaxial test.3.2.4 effective confining stressthe confining pressure (thedifference between the cell pressure and the pore-water pres-sure) prior to shearing the specimen.3
25、.2.5 effective force, (F)the force transmitted through asoil or rock mass by intergranular pressures.3.2.6 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 d
26、issipated by the specimen and apparatus, seeFig. 1.3.2.7 load durationthe time interval the specimen issubjected to a cyclic deviator stress.3.2.8 principal stressthe stress normal to one of threemutually perpendicular planes on which the shear stresses at apoint in a body are zero.3.2.9 Youngs modu
27、lus (modulus of elasticity) FL2theratio of stress to strain for a material under given loadingconditions; numerically equal to the slope of the tangent or thesecant of a stress-strain curve (same as Terminology D 653).4. Summary of Test Method4.1 The cyclic triaxial test consists of imposing either
28、acyclic axial deviator stress of fixed magnitude (load control) orcyclic axial deformation (stroke control) on a cylindrical soilspecimen enclosed in a triaxial pressure cell. The resultingaxial strain and axial stress are measured and used to calculateeither stress-dependent or stroke-dependent mod
29、ulus anddamping.5. Significance and Use5.1 The cyclic triaxial modulus and damping test providesparameters that may be considered for use in dynamic, linearand non-linear analytical methods. These test methods are usedfor the performance evaluation of both natural and engineeredstructures under dyna
30、mic of cyclic loads such as caused byearthquakes, ocean wave, or blast.5.2 One of the primary purposes of these test methods is toobtain data that are used to calculate Youngs modulus.NOTE 1The quality of the result produced by this standard isdependent on the competence of the personnel performing
31、it, and thesuitability of the equipment and facilities used. Agencies that meet thecriteria of Practice D 3740 are generally considered capable of competentand objective testing/sampling/inspection/etc. Users of this standard arecautioned that compliance with Practice D 3740 does not in itself assur
32、e2Annual 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 ApparatusD 3999 91 (2003)2reliable results. Reliable results depend on many factors; Practice D 3740provides a mea
33、ns of evaluating some of those factors.6. Apparatus6.1 GeneralIn many ways, triaxial equipment suitable forcyclic triaxial modulus and damping tests is similar to equip-ment used for the consolidated-undrained triaxial compressiontest (see Test Method D 4767). However, there are specialfeatures desc
34、ribed in the following sections that are required toperform acceptable cyclic triaxial tests. A schematic represen-tation of the various components comprising a typical triaxialmodulus and damping test setup is shown in Fig. 2.6.2 Triaxial Pressure CellThe primary considerations inselecting the cell
35、 are tolerances for the piston, top platen, andlow friction piston seal, Fig. 3.6.2.1 Two linear ball bushings or similar bearings should beused to guide the load rod to minimize friction and to maintainalignment.6.2.2 The load rod diameter should be large enough tominimize lateral bending. A minimu
36、m load rod diameter of16the specimen diameter has been used successfully in manylaboratories.6.2.3 The load rod seal is a critical element in triaxial celldesign for cyclic soils testing if an external load cell connectedto the loading rod is employed. The seal must exert negligiblefriction on the l
37、oad rod. The maximum acceptable pistonfriction tolerable without applying load corrections is com-monly considered to be 62 % of the maximum single ampli-tude cyclic load applied in the test, refer to Fig. 4. The use ofFIG. 2 Schematic Representation of Load or Stroke-Controlled Cyclic Triaxial Test
38、 SetupFIG. 3 Typical Cyclic Triaxial Pressure CellD 3999 91 (2003)3a seal described in 9.1 and described by Ladd and Dutko4, andChan5will meet these requirements.6.2.4 Top and bottom platen alignment is critical to avoidincreasing a nonuniform state of stress in the specimen.Internal tie-rod triaxia
39、l cells have worked well at a number oflaboratories. These cells allow the placement of the cell wallafter the specimen is in place between the loading platens.Acceptable limits on platen eccentricity and parallelism areshown in Fig. 5.6.2.5 Since axial loading in cyclic triaxial tests is in exten-s
40、ion as well as in compression, the load rod shall be rigidlyconnected to the top platen by a method such as one of thoseshown in Fig. 6.6.2.6 There shall be provision for specimen drainage at boththe top and bottom platens.6.3 Cyclic Loading Equipment:6.3.1 Cyclic loading equipment used for load con
41、trolledcyclic triaxial tests must be capable of applying a uniformsinusoidal load at a frequency within the range of 0.1 to 2 Hz.The loading device must be able to maintain uniform cyclicloadings to at least 0.5 % double amplitude stress, refer to Fig.4. Unsymmetrical compression-extension load peak
42、s, nonuni-formity of pulse duration, “ringing”, or load fall-off at largestrains must not exceed tolerances illustrated in Fig. 7. Theequipment must also be able to apply the cyclic load about aninitial static load on the loading rod.6.3.2 Cyclic loading equipment used for deformation-controlled cyc
43、lic 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 point or follow thespecimen as it deforms. The type of apparatus typicallyemployed can range
44、 from a simple cam to a closed loopelectro-hydraulic system.6.4 Recording Equipment:6.4.1 Load, displacement, and pore water pressure transduc-ers are required to monitor specimen behavior during cyclicloading; provisions for monitoring the chamber pressure duringcyclic loading are optional.6.4.2 Lo
45、ad MeasurementGenerally, the load cell capacityshould be no greater than five times the total maximum loadapplied to the test specimen to ensure that the necessarymeasurement accuracy is achieved. The minimum performancecharacteristics of the load cell are presented in Table 1.6.4.3 Axial Deformatio
46、n MeasurementDisplacementmeasuring devices such as linear variable differential trans-former (LVDT), Potentiometer-type deformation transducers,and eddy current sensors may be used if they meet the requiredperformance criteria (see Table 1). Accurate deformationmeasurements require that the transduc
47、er be properly mountedto avoid excessive mechanical system compression betweenthe load frame, the triaxial cell, the load cell, and the loadingpiston.6.4.4 Pressure- and Vacuum-Control DevicesThe cham-ber pressure and back pressure control devices shall be capableof applying and controlling pressure
48、s to within 62 psi (14 kPa)4Ladd, R. S., and Dutko, P., “Small Strain Measurements Using TriaxialApparatus,” Advances In The Art of Testing Soils Under Cyclic Conditions,V.Khosla, ed., American Society of Civil Engineers, 1985.5Chan, C. K., “Low Friction Seal System” Journal of the GeotechnicalEngin
49、eering Division, American Society of Civil Engineers, Vol. 101, GT-9, 1975,pp. 991995.NOTE 1Frequency =1PERIOD =1T .FIG. 4 Definitions Related to Cyclic LoadingFIG. 5 Limits on Acceptable Platen and Load Rod Alignment: (a)eccentricity, (b) parallelism, (c) eccentricity between Top Platenand SampleD 3999 91 (2003)4for effective consolidation pressures. The vacuum controldevice shall be capable of applying and controlling partialvacuums to within 62 psi (14 kPa). The devices may consist ofself-compensating mercury pots, pneumatic pressure regula-tors,
