ASTM D6467-2006a Standard Test Method for Torsional Ring Shear Test to Determine Drained Residual Shear Strength of Cohesive Soils《用扭矩环剪切试验测定粘性土壤排水残余抗剪强度的标准试验方法》.pdf

《ASTM D6467-2006a Standard Test Method for Torsional Ring Shear Test to Determine Drained Residual Shear Strength of Cohesive Soils《用扭矩环剪切试验测定粘性土壤排水残余抗剪强度的标准试验方法》.pdf》由会员分享，可在线阅读，更多相关《ASTM D6467-2006a Standard Test Method for Torsional Ring Shear Test to Determine Drained Residual Shear Strength of Cohesive Soils《用扭矩环剪切试验测定粘性土壤排水残余抗剪强度的标准试验方法》.pdf（6页珍藏版）》请在麦多课文档分享上搜索。

1、Designation: D 6467 06aStandard Test Method forTorsional Ring Shear Test to Determine Drained ResidualShear Strength of Cohesive Soils1This standard is issued under the fixed designation D 6467; the number immediately following the designation indicates the year oforiginal adoption or, in the case o

2、f 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. Scope*1.1 This test method provides a procedure for performing atorsional ring shear test under a drai

3、ned condition to determinethe residual shear strength of cohesive soils. An undisturbedspecimen can be used for testing. However, obtaining a naturalslip surface specimen, determining the direction of fieldshearing, and trimming and properly aligning the usuallynon-horizontal shear surface in the ri

4、ng shear apparatus isdifficult. As a result, this test method focuses on the use of areconstituted specimen to measure the residual strength. Thistest method is performed by deforming a presheared, reconsti-tuted specimen at a controlled displacement rate until theconstant minimum drained shear resi

5、stance is offered on asingle shear plane determined by the configuration of theapparatus. An unlimited amount of continuous shear displace-ment can be achieved to obtain a residual strength condition.Generally, three or more normal stresses are applied to a testspecimen to determine the drained resi

6、dual failure envelope. Aseparate test specimen may be used for each normal stress.1.2 A shear stress-displacement relationship may be ob-tained from this test method. However, a shear stress-strainrelationship or any associated quantity, such as modulus,cannot be determined from this test method bec

7、ause possiblesoil extrusion and volume change prevents defining the heightneeded in the shear strain calculations. As a result, shear straincannot be calculated but shear displacement can be calculated.1.3 The selection of normal stresses and final determinationof the shear strength envelope for des

8、ign analyses and thecriteria to interpret and evaluate the test results are theresponsibility of the engineer or office requesting the test.1.4 The values stated in SI units are to be regarded as thestandard. The values stated in inch-pound units are approxi-mated.1.5 All measured and calculated val

9、ues shall conform to theguidelines for significant digits and rounding established inPractice D 6026.1.6 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 hea

10、lth practices and determine the applica-bility of regulatory limitations prior to use.2. Referenced Documents2.1 ASTM Standards:2D 422 Test Method for Particle-Size Analysis of SoilsD 653 Terminology Relating to Soil, Rock, and ContainedFluidsD 854 Test Methods for Specific Gravity of Soil Solids by

11、Water PycnometerD 2216 Test Methods for Laboratory Determination of Wa-ter (Moisture) Content of Soil and Rock by MassD 2435 Test Methods for One-Dimensional ConsolidationProperties of Soils Using Incremental LoadingD 2487 Practice for Classification of Soils for EngineeringPurposes (Unified Soil Cl

12、assification System)D 3740 Practice for Minimum Requirements for AgenciesEngaged in the Testing and/or Inspection of Soil and Rockas Used in Engineering Design and ConstructionD 4318 Test Methods for Liquid Limit, Plastic Limit, andPlasticity Index of SoilsD 6026 Practice for Using Significant Digit

13、s in Geotechni-cal Data3. Terminology3.1 DefinitionsFor definitions of terms used in this testmethod, refer to Terminology D 653.3.2 Definitions of Terms Specific to This Standard:3.2.1 consolidatedsoil specimen condition after primaryconsolidation under a specific normal stress.3.2.2 preshearedsoil

14、 specimen condition after shearing atleast one revolution of the ring in the direction of shear tocreate a failure surface prior to drained shearing.1This test method is under the jurisdiction ofASTM Committee D18 on Soil andRock and is the direct responsibility of Subcommittee D18.05 on Strength an

15、dCompressibility of Soils.Current edition approved May 1, 2006. Published June 2006. Originallyapproved in 1999. Last previous edition approved in 2006 as D 6467 06.2For referenced ASTM standards, visit the ASTM website, www.astm.org, orcontact ASTM Customer Service at serviceastm.org. For Annual Bo

16、ok of ASTMStandards volume information, refer to the standards Document Summary page onthe ASTM website.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.3.2.3 residual

17、shear forcethe shear force being applied tothe specimen when the shear resistance neither increases nordecreases with continued shear displacement.3.2.4 residual shear strengththe constant minimum resis-tance of soil to shear along a fully developed failure surfaceand equals the residual shear force

18、 divided by the cross-sectional area of the specimen.4. Summary of Test Method4.1 This test method consists of placing the specimen in theannular specimen container, applying a predetermined normalstress through the top loading platen, providing for wetting anddraining of the specimen (optional); co

19、nsolidating the speci-men under the normal stress; decreasing the normal stress toyield an overconsolidated specimen; preshearing the specimenby rotating the specimen container against the top loadingplaten for one revolution; applying a constant rate of sheardeformation; and measuring the shearing

20、force and displace-ment until a constant minimum resistance is reached.5. Significance and Use5.1 The apparatus keeps the cross-sectional area of the shearsurface constant during shear and shears the specimen continu-ously in one rotational direction for any magnitude of displace-ment. This allows c

21、lay particles to become oriented parallel tothe direction of shear and a residual strength condition todevelop.5.2 The apparatus allows a reconstituted specimen to beoverconsolidated and presheared prior to drained shearing.This simulates the field conditions that lead to a preexistingshear surface

22、along which the drained residual strength can bemobilized.5.3 The ring shear test is suited to the relatively rapiddetermination of drained residual shear strength because of theshort drainage path through the thin specimen, and the capa-bility of testing one specimen under different normal stresses

23、 toquickly obtain a shear strength envelope.5.4 The test results are primarily applicable to assess theshear strength in slopes that contain a preexisting shear surface,such as old landslides, and sheared bedding planes, joints, orfaults.NOTE 1Notwithstanding the statements on precision and bias con

24、-tained in this test method: The precision of this test method is dependenton the competence of the personnel performing it and the suitability of theequipment and facilities used. Agencies that meet the criteria of PracticeD 3740 are generally considered capable of competent testing. Users ofthis t

25、est method are cautioned that compliance with Practice D 3740 doesnot ensure reliable testing. Reliable testing depends on several factors;Practice D 3740 provides a means of evaluating some of those factors.6. Apparatus6.1 Shear Device, to hold the specimen securely betweentwo porous inserts. The s

26、hear device shall provide a means forapplying a normal stress to the faces of the specimen, formeasuring changes in thickness of the specimen, for permittingdrainage of water through the porous inserts at the top andbottom boundaries of the specimen, and for submerging thespecimen in water. The devi

27、ce shall be capable of applying atorque to the specimen along a shear plane parallel to the facesof the specimen. A number of different ring shear devices arecommercially available, in practice, or are being developed soa general description of a ring shear device is presented withoutschematic diagr

28、ams. The location of the shear plane dependson the configuration of the apparatus. As a result, the shearplane may be located near a soil/porous insert interface or atthe mid-height of the specimen if an upper ring can beseparated from a bottom ring as is done in a direct shear box.The device shall

29、have low friction along the inner and outerwalls of the specimen container developed during shearing.Friction may be reduced by having the shear plane occur at thetop of the specimen container, modifying the specimen con-tainer walls with low-friction material, or exposing the shearplane by separati

30、ng the top and bottom portions of thespecimen container. The frames that hold the specimen shall besufficiently rigid to prevent their distortion during shearing.The various parts of the shear device shall be made of amaterial such as stainless steel, bronze, or coated aluminumthat is not subject to

31、 corrosion by moisture or substances withinthe soil. Dissimilar metals, which may cause galvanic action,are not permitted.6.2 Specimen Container, a device containing an annularcavity for the soil specimen with an inside diameter not lessthan 50 mm (2 in.) and an inside to outside diameter ratio notl

32、ess than 0.6. The container has provisions for drainage throughthe top and bottom. The initial specimen depth, before con-solidation and preshearing, is not less than 5 mm (0.2 in.). Themaximum particle size is limited to 10 % of the initialspecimen height as stated in the test specimen description.

33、 Soilextrusion and changes in specimen volume during shearpreclude use of the device for undrained testing unless thedevice can provide a constant volume or undrained condition.6.3 Torque Arm/Loading Platen Assembly, may have differ-ent bearing stops for the proving rings, load cells, or force ortor

34、que transducers to provide different options for the torquemeasurement.6.4 Porous Inserts, two bronze or stainless steel porousinserts mounted on the top loading platen and the bottom of thespecimen container cavity to allow drainage from the soilspecimen along the top and bottom boundaries. The ins

35、erts aidin transfer of shear stress to the top and bottom boundaries ofthe specimen. The inserts must be sufficiently serrated todevelop a strong interlock with the soil specimen. The perme-ability of the inserts shall be substantially greater than that ofthe soil, but shall be textured fine enough

36、to prevent excessiveintrusion of the soil into the pores of the insert. The outer andinner diameters of the inserts shall be 0.1 mm (0.004 in.) less,and greater than those of the specimen annular cavity, respec-tively. The serration should have a depth of between 10 and15 % of the initial specimen h

37、eight.NOTE 2Exact criteria for porous insert texture and permeability havenot been established. For normal soil testing, medium-grade inserts witha permeability of about 5.0 3 104to 1.0 3 103cm/s (0.5 to 1.0 3 103ft/year) are appropriate for testing silts and clays. It is important that thepermeabil

38、ity of the porous insert is not reduced by the collection of soilparticles in the pores of the insert; hence frequent checking and cleaning(by flushing and boiling, or by ultrasonic cleaning) are required to ensurethe necessary permeability.6.5 Loading Devices:D 6467 06a26.5.1 Device for Applying an

39、d Measuring the NormalForceNormal force is usually applied by a lever-loadingyoke that is activated by dead weights (masses). The deviceshall be capable of rapidly applying and maintaining thenormal force to within 61 % of the specified force.6.5.2 Device for Shearing the SpecimenThis device shallbe

40、 capable of shearing the specimen at a uniform rate ofdisplacement, with less than 65 % deviation. The rate to beapplied depends upon the consolidation characteristics of thesoil (see 9.5.1). The rate is usually maintained with an electricmotor and gear box arrangement.6.6 Shear Force Measurement De

41、vice, two proving rings,load cells, or a torque transducer accurate to measure a force of0.2 N (0.05 lbf).6.7 Water Bath, container for the shear device and waterneeded to inundate the specimen.6.8 Controlled High-Humidity RoomIf required, for pre-paring the specimen, such that the water content gai

42、n or lossduring specimen rehydration is minimized.6.9 Deformation Indicators, dial gage, or other suitabledevice, capable of measuring the change in thickness of thespecimen, with a sensitivity of at least 0.0025 mm (0.0001 in.).Etched scale on circumference of the ring base to measure thedegrees tr

43、aveled, and thus the shear displacement, or othermethods capable of obtaining a sensitivity of at least 2.6.10 Equipment for Determination of Water Content,inaccordance in Test Method D 2216.6.11 Miscellaneous Equipment, including timing devicewith a second hand, site-specific, distilled or deminera

44、lizedwater, mortar, pestle, spatulas, razor blades, straightedge, andso forth.7. Test Specimen7.1 The sample used for specimen preparation is to besufficiently large so that a ring shear specimen and specimensfor index property tests can be prepared.7.2 If an undisturbed specimen is desired, the she

45、ar surfacesample should be trimmed to produce an annular specimen.This can be accomplished using an annular trimming ring tofacilitate trimming and insertion of the specimen into theannular specimen container. A field shear surface may consistof small seams of clayey material surrounded by material

46、witha coarser gradation. If so, only the clayey shear zone materialshould be tested and not the coarser surrounding material tosimulate field shearing conditions. The undisturbed specimenshould be trimmed in a controlled temperature and humidityenvironment to minimize moisture loss or gain.7.3 Recon

47、stituted silt and clay specimens may be preparedby crushing an air-dried representative sample and passing itthrough the appropriate sieve, for example, opening size lessthan or equal to 10 % of the initial specimen height.7.4 Reconstituted specimens of heavily overconsolidatedclays, mudstones, clay

48、stones, and shales may be prepared byball-milling an air-dried representative sample and passing itthrough the U.S. Standard sieve #200. The ball-milling facili-tates disaggregation of the clay particles and reduces the sheardisplacement required to achieve a residual strength condition.If ball-mill

49、ing is not used, greater shear displacement will berequired to disaggregate the clay particles and achieve aresidual strength condition in the apparatus. The additionalshear displacement can be large and create testing problemssuch as significant soil extrusion and wall friction.7.5 Another technique for obtaining a reconstituted speci-men is pushing a representative sample, at the as-receivedwater content, through the appropriate sieve. Soil with morethan 25 % organic content is to be reconstituted without drying.7.6 The reconstituted specimens should be prepared in aco