1、Designation: D 2435 04Standard Test Methods forOne-Dimensional Consolidation Properties of Soils UsingIncremental Loading1This standard is issued under the fixed designation D 2435; the number immediately following the designation indicates the year oforiginal adoption or, in the case of revision, t
2、he 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 These test methods covers procedures for determiningthe magnitude and rate of consolidation of soil when
3、it isrestrained laterally and drained axially while subjected toincrementally applied controlled-stress loading. Two alterna-tive procedures are provided as follows:1.1.1 Test Method AThis test method is performed withconstant load increment duration of 24 h, or multiples thereof.Time-deformation re
4、adings are required on a minimum of twoload increments.1.1.2 Test Method BTime-deformation readings are re-quired on all load increments. Successive load increments areapplied after 100 % primary consolidation is reached, or atconstant time increments as described in Test Method A.NOTE 1The determin
5、ation of the rate and magnitude of consolidationof soil when it is subjected to controlled-strain loading is covered by TestMethod D 4186.1.2 This test method is most commonly performed onundisturbed samples of fine grained soils naturally sedimentedin water, however, the basic test procedure is app
6、licable, aswell, to specimens of compacted soils and undisturbed samplesof soils formed by other processes such as weathering orchemical alteration. Evaluation techniques specified in this testmethod are generally applicable to soils naturally sedimentedin water. Tests performed on other soils such
7、as compacted andresidual (weathered or chemically altered) soils may requirespecial evaluation techniques.1.3 It shall be the responsibility of the agency requestingthis test to specify the magnitude and sequence of each loadincrement, including the location of a rebound cycle, ifrequired, and, for
8、Test Method A, the load increments forwhich time-deformation readings are desired.NOTE 2Time-deformation readings are required to determine the timefor completion of primary consolidation and for evaluating the coefficientof consolidation, cv. Since cvvaries with stress level and load increment(load
9、ing or unloading), the load increments with timed readings must beselected with specific reference to the individual project.Alternatively, therequesting agency may specify Test Method B wherein the time-deformation readings are taken on all load increments.1.4 The values stated in SI units are to b
10、e regarded as thestandard. The values stated in inch-pound units are approxi-mate and given for guidance only. Reporting of test results inunits other than SI shall not be regarded as nonconformancewith this test method.1.4.1 In the engineering profession it is customary practiceto use, interchangea
11、bly, units representing both mass and force,unless dynamic calculations (F = Ma) are involved. This im-plicitly combines two separate systems of units, that is, theabsolute system and the gravimetric system. It is scientificallyundesirable to combine two separate systems within a singlestandard. Thi
12、s test method has been written using SI units;however, inch-pound conversions are given in the gravimetricsystem, where the pound (lbf) represents a unit of force(weight). The use of balances or scales recording pounds ofmass (lbm), or the recording of density in lb/ft3should not beregarded as nonco
13、nformance with this test method.1.5 Observed and calculated values shall conform to theguidelines for significant digits and rounding established inPractice D 6026, unless superceded by this test method, unlesssuperceded by this test method.1.5.1 The method used to specify how data are collected,cal
14、culated, 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.1.6 This standard does not purport to address all of thesafety concerns, if any,
15、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.1These test methods are under the jurisdiction ofASTM Committee D18 on Soiland Rock and is the d
16、irect responsibility of subcommittee D18.05on StructuralProperties of Soil .Current edition approved Nov. 1, 2004. Published November 2004. Originallyapproved in 1965. Last previous edition approved in 2003 as D 2435 03.1*A Summary of Changes section appears at the end of this standard.Copyright AST
17、M International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.2. Referenced Documents2.1 ASTM Standards:D 422 Method for Particle-Size Analysis of Soils2D 653 Terminology Relating to Soil, Rock, and ContainedFluids2D 854 Test Method for Specific Gravity of Soil
18、s2D 1587 Practice For Thin-Walled Tube Geotechnical Sam-pling of Soils2D 2216 Test Method for Laboratory Determination of Water(Moisture) Content of Soil and Rock2D 2487 Classification of Soils for Engineering Purposes2D 2488 Practice for Description and Identification of Soils(Visual-Manual Procedu
19、re)2D 3550 Practice for Ring-Lined Barrel Sampling of Soils2D 3740 Practice for Minimum Requirements for AgenciesEngaged in the Testing or Inspection, or both, of Soil andRock as Used in Engineering Design and Construction2D 4186 Test Method for One-Dimensional ConsolidationProperties of Soils Using
20、 Controlled-Strain Loading2D4220 Practice for Preserving and Transporting SoilSamples2D 4318 Test Method for Liquid Limit, Plastic Limit, andPlasticity Index of Soils2D 4452 Methods for X-Ray Radiography of Soil Samples2D 4546 Test Methods for One-Dimensional Swell or Settle-ment Potential of Cohesi
21、ve Soils2D 6026 Practice for Using Significant Digits in Geotechni-cal Data3. Terminology3.1 DefinitionsThe definitions of terms used in this testmethod shall be in accordance with Terminology D 653.4. Summary of Test Method4.1 In this test method a soil specimen is restrained laterallyand loaded ax
22、ially with total stress increments. Each stressincrement is maintained until excess pore water pressures arecompletely dissipated. During the consolidation process, mea-surements are made of change in the specimen height and thesedata are used to determine the relationship between theeffective stres
23、s and void ratio or strain, and the rate at whichconsolidation can occur by evaluating the coefficient of con-solidation.5. Significance and Use5.1 The data from the consolidation test are used to estimatethe magnitude and rate of both differential and total settlementof a structure or earthfill. Es
24、timates of this type are of keyimportance in the design of engineered structures and theevaluation of their performance.5.2 The test results can be greatly affected by sampledisturbance. Careful selection and preparation of test speci-mens is required to minimize disturbance.NOTE 3Notwithstanding th
25、e 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 suitability of theequipment and facilities used. Agencies that meet the criteria of PracticeD 3740 generally are considered capable
26、of competent and objectivetesting. Users of this test method are cautioned that compliance withPractice D 3740 does not assure reliable testing. Reliable testing dependson many factors, and Practice D 3740 provides a means of evaluationsome of these factors.5.3 Consolidation test results are depende
27、nt upon the mag-nitude of the load increments. Traditionally, the load is doubledfor each increment resulting in a load-increment ratio of 1. Forundisturbed samples, this load procedure has provided datafrom which estimates of the preconsolidation pressure alsoreferred to as the maximum past pressur
28、e, using establishedevaluation techniques, compare directly with field measure-ment. Other load schedules may be used to model particularfield conditions or meet special requirements. For example, itmay be desirable to inundate and load the specimen inaccordance with the wetting or loading pattern e
29、xpected in thefield in order to best simulate the response. Smaller thanstandard load increment ratios may be desirable for soils thatare highly sensitive or whose response is highly dependent onstrain rate. The test method specified to estimate the precon-solidation pressure provides a simple techn
30、ique to verify thatone set of time readings are taken after the preconsolidationpressure. Several other evaluation techniques exist and mayyield different estimates of the preconsolidation pressure.Therefore, the requesting agency may specify an alternatetechnique to estimate the preconsolidation pr
31、essure.5.4 Consolidation test results are dependent upon the dura-tion of each load increment. Traditionally, the load duration isthe same for each increment and equal to 24 h. For some soils,the rate of consolidation is such that complete consolidation(dissipation of excess pore pressure) will requ
32、ire more than 24h. The apparatus in general use does not have provisions forformal verification of pore pressure dissipation. It is necessaryto use an interpretation technique which indirectly determinesthat consolidation is complete. This test method specifies twotechniques, however the requesting
33、agency may specify analternative technique and still be in conformance with this testmethod.5.5 The apparatus in general use for this test method doesnot have provisions for verification of saturation. Most undis-turbed samples taken from below the water table will besaturated. However, the time rat
34、e of deformation is verysensitive to degree of saturation and caution must be exercisedregarding estimates for duration of settlements when partiallysaturated conditions prevail. The extent to which partialsaturation influences the test results may be a part of the testevaluation and may include app
35、lication of theoretical modelsother than conventional consolidation theory.Alternatively, thetest may be performed using an apparatus equipped to saturatethe specimen.5.6 This test method uses conventional consolidation theorybased on Terzaghis consolidation equation to compute thecoefficient of con
36、solidation, cv. The analysis is based upon thefollowing assumptions:5.6.1 The soil is saturated and has homogeneous properties;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
37、, refer to the standards Document Summary page onthe ASTM website.D 2435 0425.6.2 The flow of pore water is in the vertical direction;5.6.3 The compressibility of soil particles and pore water isnegligible compared to the compressibility of the soil skeleton;5.6.4 The stress-strain relationship is l
38、inear over the loadincrement;5.6.5 The ratio of soil permeability to soil compressibility isconstant over the load increment; and5.6.6 Darcys law for flow through porous media applies.6. Apparatus6.1 Load DeviceA suitable device for applying verticalloads or total stresses to the specimen. The devic
39、e shall becapable of maintaining specified loads for long periods of timewith a precision of 6 0.5 % of the applied load and shall permitquick application of a given load increment without significantimpact.NOTE 4Load application generally should be completed in a timecorresponding to 0.01 t100or le
40、ss. For soils where primary consolidationis completed in 3 min, load application should be less than 2 s.6.2 ConsolidometerA device to hold the specimen in aring that is either fixed to the base or floating (supported byfriction on periphery of specimen) with porous disks on eachface of the specimen
41、. The inside diameter of the ring shall bedetermined to a tolerance of 0.075 mm (0.003 in.). Theconsolidometer shall also provide a means of submerging thespecimen, for transmitting the concentric vertical load to theporous disks, and for measuring the change in height ofspecimen.6.2.1 Minimum Speci
42、men DiameterThe minimum speci-men diameter shall be 50 mm (2.00 in.).6.2.2 Minimum Specimen HeightThe minimum initialspecimen height shall be 12 mm (0.5 in.), but shall be not lessthan ten times the maximum particle diameter.NOTE 5If large particles are found in the specimen after testing,include in
43、 the report this visual observation or the results of a particle sizeanalysis in accordance with Method D 422 (except the minimum samplesize requirement shall be waived).6.2.3 Minimum Specimen Diameter-to-Height RatioTheminimum specimen diameter-to-height ratio shall be 2.5.NOTE 6The use of greater
44、diameter-to-height ratios is recommended.To minimize the effects of friction between the sides of the specimen andring, a diameter-to-height ratio greater than four is preferable.6.2.4 Specimen Ring RigidityThe rigidity of the ring shallbe such that, under hydrostatic stress conditions in the speci-
45、men, the change in diameter of the ring will not exceed 0.03 %of the diameter under the greatest load applied.6.2.5 Specimen Ring MaterialThe ring shall be made of amaterial that is noncorrosive in relation to the soil tested. Theinner surface shall be highly polished or shall be coated with alow-fr
46、iction material. Silicone grease or molybdenum disulfideis recommended; polytetrafluoroethylene is recommended fornonsandy soils.6.3 Porous DisksThe porous disks shall be of siliconcarbide, aluminum oxide, or similar noncorrosive material.Thegrade of the disks shall be fine enough to prevent intrusi
47、on ofsoil into the pores. If necessary, a filter paper (see Note 7) maybe used to prevent intrusion of the soil into the disks; however,the permeability of the disks, and filter paper, if used, must beat least one order of magnitude higher than that of thespecimen.NOTE 7Whatman No. 54 filter paper h
48、as been found to meetrequirements for permeability and durability.6.3.1 DiameterThe diameter of the top disk shall be 0.2 to0.5 mm (0.01 to 0.02 in.) less than the inside diameter of thering. If a floating ring is used, the bottom disk shall have thesame diameter as the top disk.NOTE 8The use of tap
49、ered disks is recommended, with the largerdiameter in contact with the soil.6.3.2 ThicknessThickness of the disks shall be sufficientto prevent breaking. The top disk shall be loaded through acorrosion-resistant plate of sufficient rigidity to prevent break-age of the disk.6.3.3 MaintenanceThe disks shall be clean and free fromcracks, chips, and nonuniformities. New porous disks shouldbe boiled for at least 10 minutes and left in the water to cool toambient temperature before use. Immediately after each use,clean the porous disks with a nonabrasive brush and b
