1、Designation: D 3080 04Standard Test Method forDirect Shear Test of Soils Under Consolidated DrainedConditions1This standard is issued under the fixed designation D 3080; the number immediately following the designation indicates the year oforiginal adoption or, in the case of revision, the year of l
2、ast 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 covers the determination of the con-solidated drained shear strength of a soil material in directshe
3、ar. The test is performed by deforming a specimen at acontrolled strain rate on or near a single shear plane determinedby the configuration of the apparatus. Generally, three or morespecimens are tested, each under a different normal load, todetermine the effects upon shear resistance and displaceme
4、nt,and strength properties such as Mohr strength envelopes.1.2 Shear stresses and displacements are nonuniformly dis-tributed within the specimen. An appropriate height cannot bedefined for calculation of shear strains. Therefore, stress-strainrelationships or any associated quantity such as modulus
5、,cannot be determined from this test.1.3 The determination of strength envelopes and the devel-opment of criteria to interpret and evaluate test results are leftto the engineer or office requesting the test.1.4 The results of the test may be affected by the presence ofsoil or rock particles, or both
6、, (see Section 7).1.5 Test conditions including normal stress and moistureenvironment are selected which represent the field conditionsbeing investigated. The rate of shearing should be slow enoughto ensure drained conditions.1.6 There may be instances when the gap between the platesshould be increa
7、sed to accommodate sand sizes greater than thespecified gap. Presently there is insufficient information avail-able for specifying gap dimension based on particle sizedistribution.1.7 The values stated in inch-pound units are to be regardedas the standard. Within this test method the SI units are sh
8、ownin brackets. The values stated in each system are not exactequivalents; therefore, each system must be used indepen-dently of each other.1.8 All observed and calculated values shall conform to theguidelines for significant digits and rounding established inPractice D 6026.1.8.1 The method used to
9、 specify how data are collected,calculated, or recorded in this standard is not directly related tothe accuracy to which the data can be applied in 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
10、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 prior to use.2. Referenced Documents2.1 ASTM Standards:2D 422 Method for P
11、article-Size Analysis of SoilsD 653 Terminology Relating to Soil, Rock, and ContainedFluidsD 698 Test Method for Laboratory Compaction Character-istics of Soil Using Standard Effort (12 400 ft-lbf/ft)D 1557 Test Method for Laboratory Compaction Character-istics of Soil Using Modified Effort (56 000
12、ft-lbf/ft)D 1587 Practice for Thin-Walled Geotechnical Tube Sam-pling of SoilsD 2216 Method for Laboratory Determination of Water(Moisture) Content of Soil and RockD 2435 Test Method for One Dimensional ConsolidationProperties of SoilsD 2487 Test Method for Classification of Soils for Engi-neering P
13、urposesD 2488 Practice for Description and Identification of Soils(Visual-Manual Procedure)D 3740 Practice for Minimum Requirements for AgenciesEngaged in the Testing and/or Inspection of Soil and RockD 4220 Practices for Preserving and Transporting SoilSamplesD 4318 Test Method for Liquid Limit, Pl
14、astic Limit, andPlasticity Index of Soils1This test method is under the jurisdiction ofASTM Committee D18 on Soil andRock and is the direct responsibility of Subcommittee D18.05 on StructuralProperties of Soils.Current edition approved Nov. 1, 2004. Published December 20043. Originallyapproved in 19
15、72. Last previous edition approved in 2003 as D 3080 03.2For referenced ASTM standards, visit the ASTM website, www.astm.org, orcontact ASTM Customer Service at serviceastm.org. For Annual Book of ASTMStandards volume information, refer to the standards Document Summary page onthe ASTM website.1*A S
16、ummary 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.D 4753 Specifications for Evaluating, Selecting, and Speci-fying Balances and Scales for Use in Soil Rock andConstruction Ma
17、terials TestingD 6026 Practice for Using Significant Digits in Geotechni-cal Data3. Terminology3.1 DefinitionsFor definitions of terms used in this testmethod, refer to Terminology D 653.3.2 Description of Terms Specific to This Standard:3.2.1 Relative Lateral DisplacementThe horizontal dis-placemen
18、t of the top and bottom shear box halves.3.2.2 FailureThe stress condition at failure for a testspecimen. Failure is often taken to correspond to the maximumshear stress attained, or the shear stress at 15 to 20 percentrelative lateral displacement. Depending on soil behavior andfield application, o
19、ther suitable criteria may be defined.4. Summary of Test Method4.1 This test method consists of placing the test specimen inthe direct shear device, applying a predetermined normalstress, providing for wetting or draining of the test specimen, orboth, consolidating the specimen under the normal stre
20、ss,unlocking the frames that hold the test specimen, and displac-ing one frame horizontally with respect to the other at aconstant rate of shearing deformation and measuring theshearing force and horizontal displacements as the specimen issheared (Fig. 1).5. Significance and Use5.1 The direct shear
21、test is suited to the relatively rapiddetermination of consolidated drained strength properties be-cause the drainage paths through the test specimen are short,thereby allowing excess pore pressure to be dissipated morerapidly than with other drained stress tests. The test can bemade on all soil mat
22、erials and undisturbed, remolded orcompacted materials. There is however, a limitation on maxi-mum particle size (see 7.2).5.2 The test results are applicable to assessing strength in afield situation where complete consolidation has occurredunder the existing normal stresses. Failure is reached slo
23、wlyunder drained conditions so that excess pore pressures aredissipated. The results from several tests may be used toexpress the relationship between consolidation stress anddrained shear strength.5.3 During the direct shear test, there is rotation of principalstresses, which may or may not model f
24、ield conditions.Moreover, failure may not occur on the weak plane sincefailure is forced to occur on or near a horizontal plane at themiddle of the specimen. The fixed location of the plane in thetest can be an advantage in determining the shear resistancealong recognizable weak planes within the so
25、il material and fortesting interfaces between dissimilar materials.5.4 Shear stresses and displacements are nonuniformly dis-tributed within the specimen, and an appropriate height is notdefined for calculating shear strains or any associated engineer-ing quantity. The slow rate of displacement prov
26、ides fordissipation of excess pore pressures, but it also permits plasticflow of soft cohesive soils. Care should be taken to ensure thatthe testing conditions represent those conditions being inves-tigated.5.5 The range in normal stresses, rate of shearing, andgeneral test conditions should be sele
27、cted to approximate thespecific soil conditions being investigated.NOTE 1Notwithstanding the statement on precision and bias con-tained in this standard: The precision of this test method is dependent onthe competence of the personnel performing the test and the suitability ofthe equipment and facil
28、ities used. Agencies which meet the criteria ofPractice D 3740 are generally considered capable of competent andobjective testing. Users of this test method are cautioned that compliancewith Practice D 3740 does not in itself assure reliable testing. Reliabletesting depends on several factors; Pract
29、ice D 3740 provides a means ofevaluating some of these factors.6. Apparatus6.1 Shear DeviceA device to hold the specimen securelybetween two porous inserts in such a way that torque is notapplied to the specimen. The shear device shall provide ameans of applying a normal stress to the faces of the s
30、pecimen,for measuring change in thickness of the specimen, forpermitting drainage of water through the porous inserts at thetop and bottom boundaries of the specimen, and for submerg-ing the specimen in water. The device shall be capable ofapplying a shear force to the specimen in water. The devices
31、hall be capable of applying a shear force to the specimenalong a predetermined shear plane (single shear) parallel to thefaces of the specimen. The frames that hold the specimen shallbe sufficiently rigid to prevent their distortion during shearing.The various parts of the shear device shall be made
32、 of materialnot subject to corrosion by moisture or substances within thesoil, for example, stainless steel, bronze, or aluminum, etc.Dissimilar metals, which may cause galvanic action, are notpermitted.6.2 Shear Box, a shear box, either circular or square, madeof stainless steel, bronze, or aluminu
33、m, with provisions fordrainage through the top and bottom. The box is dividedvertically by a horizontal plane into two halves of equalthickness which are fitted together with alignment screws. Theshear box is also fitted with gap screws, which control thespace (gap) between the top and bottom halves
34、 of the shearbox.6.3 Porous Inserts, Porous inserts function to allow drain-age from the soil specimen along the top and bottom bound-aries. They also function to transfer horizontal shear stressfrom the insert to the top and bottom boundaries of thespecimen. Porous inserts shall consist of silicon
35、carbide,aluminum oxide, or metal which is not subject to corrosion bysoil substances or soil moisture. The proper grade of insertdepends on the soil being tested. The permeability of the insertFIG. 1 Test Specimens in (a) Single and (b) Double ShearD 3080 042should be substantially greater than that
36、 of the soil, but shouldbe textured fine enough to prevent excessive intrusion of thesoil into the pores of the insert. The diameter or width of thetop porous insert or plate shall be 0.01 to 0.02 in. (0.2 to 0.5mm) less than that of the inside of the ring. If the insertfunctions to transfer the hor
37、izontal stress to the soil, it must besufficiently coarse to develop interlock. Sandblasting or toolingthe insert may help, but the surface of the insert should not beso irregular as to cause substantial stress concentrations in thesoil.NOTE 2Exact criteria for insert texture and permeability have n
38、otbeen established. For normal soil testing, medium grade inserts with apermeability of about 0.5 to 1.0 3 103ft/yr (5.0 3 104to 1.0 3 103cm/s) are appropriate for testing silts and clays, and coarse grade insertswith a permeability of about 0.5 to 1.0 3 105ft/yr (0.05 to 0.10 cm/s) areappropriate f
39、or sands. It is important that the permeability of the porousinsert is not reduced by the collection of soil particles in the pores of theinsert; hence frequent checking and cleaning (by flushing and boiling, orby ultrasonic cleaning) are required to ensure the necessary permeability.6.4 Loading Dev
40、ices:6.4.1 Device for Applying and Measuring the NormalForceThe normal force is applied by a lever loading yokewhich is activated by dead weights (masses) or by a pneumaticloading device. The device shall be capable of maintaining thenormal force to within 61 percent of the specified forcequickly wi
41、thout exceeding it.6.4.2 Device for Shearing the SpecimenThe device shallbe capable of shearing the specimen at a uniform rate ofdisplacement, with less than 65 percent deviation, and shouldpermit adjustment of the rate of displacement from 0.0001 to0.04 in./min (.0025 to 1.0 mm/min). The rate to be
42、 applieddepends upon the consolidation characteristics of the soils (see). The rate is usually maintained with an electric motor andgear box arrangement and the shear force is determined by aload indicating device such as a proving ring or load cell.6.4.3 The weight of the top shear box shall be les
43、s than 1percent of the applied normal force during shear: this will mostlikely require that the top shear box be supported by a counterforce, the equipment modified or the specimen sheared under agreater applied normal force.NOTE 3Shearing the test specimen at a rate greater than specified mayproduc
44、e partially drained shear results that will differ from the drainedstrength of the material.6.5 Shear Force Measurement DeviceA proving ring orload cell accurate to 0.5 lbf (2.5 N), or 1 percent of the shearforce at failure, whichever is greater.6.6 Shear Box BowlA metallic box which supports theshe
45、ar box and provides either a reaction against which one halfof the shear box is restrained, or a solid base with provisionsfor aligning one half of the shear box, which is free to movecoincident with applied shear force in a horizontal plane.6.7 Controlled High Humidity Room, if required, for pre-pa
46、ring specimens, such that water content gain or loss duringspecimen preparation is minimized.6.8 Trimmer or Cutting Ring, for trimming oversizedsamples to the inside dimensions of the shear box with aminimum of disturbance. An exterior jig may be needed tomaintain the shear box alignment.6.9 Balance
47、sa balance or scale conforming to the require-ments of Specification D 4753 readable (with no estimate) to0.1% or better.6.10 Deformation IndicatorsEither dial gages or displace-ment transformers capable of measuring the change in thick-ness of the specimen, with a sensitivity of at least 0.0001 in.
48、(0.0025 mm) and to measure horizontal displacement withsensitivity of at least 0.001 in. (0.025 mm).6.11 Apparatus for Determination of Water Content, asspecified in Test Method D 2216.6.12 Equipment for Remolding or Compacting Specimens,if applicable.6.13 Miscellaneous Equipment, including timing d
49、evicewith a second hand, distilled or demineralized water, spatulas,knives, straightedge, wire saws, etc., used in preparing thespecimen.7. Test Specimen7.1 The sample used for specimen preparation should besufficiently large so that a minimum of three similar specimenscan be prepared. Prepare the specimens in a controlled tem-perature and humidity environment to minimize moisture lossor gain.7.1.1 Extreme care shall be taken in preparing undisturbedspecimens of sensitive soils to prevent disturbance to thenatural soil structure. Determine the initial mass of the wetsp
