1、Designation: D2435/D2435M 11Standard Test Methods forOne-Dimensional Consolidation Properties of Soils UsingIncremental Loading1This standard is issued under the fixed designation D2435/D2435M; the number immediately following the designation indicates theyear of original adoption or, in the case of
2、 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.1. Scope*1.1 These test methods cover procedures for determiningthe magnitude and rate of consolidation of
3、soil when 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-defo
4、rmation readings are required on a minimum of twoload increments. This test method provides only the compres-sion curve of the specimen and the results combine bothprimary consolidation and secondary compression deforma-tions.1.1.2 Test Method BTime-deformation readings are re-quired on all load inc
5、rements. Successive load increments areapplied after 100 % primary consolidation is reached, or atconstant time increments as described in Test Method A. Thistest method provides the compression curve with explicit datato account for secondary compression, the coefficient ofconsolidation for saturat
6、ed materials, and the rate of secondarycompression.NOTE 1The determination of the rate and magnitude of consolidationof soil when it is subjected to controlled-strain loading is covered by TestMethod D4186.1.2 These test methods are most commonly performed onsaturated intact samples of fine grained
7、soils naturally sedi-mented in water, however, the basic test procedure is appli-cable, as well, to specimens of compacted soils and intactsamples of soils formed by other processes such as weatheringor chemical alteration. Evaluation techniques specified in thesetest methods assume the pore space i
8、s fully saturated and aregenerally applicable to soils naturally sedimented in water.Tests performed on other unsaturated materials such as com-pacted and residual (weathered or chemically altered) soilsmay require special evaluation techniques. In particular, therate of consolidation (interpretatio
9、n of the time curves) is onlyapplicable to fully saturated specimens.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 Test Method A, the load increments fo
10、rwhich time-deformation readings are desired. The requiredmaximum stress level depends on the purpose of the test andmust be agreed on with the requesting agency. In the absenceof specific instructions, Section 11 provides the default loadincrement and load duration schedule for a standard test.NOTE
11、 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 loading type(loading or unloading), the load increments with timed readings must beselected with specific
12、 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 These test methods do not address the use of a backpressure to saturate the specimen. Equipment is available toperform consoli
13、dation tests using back pressure saturation. Theaddition of back pressure saturation does not constitute non-conformance to these test methods.1.5 UnitsThe values stated in either SI units or inch-pound units given in brackets are to be regarded separately asstandard. The values stated in each syste
14、m may not be exactequivalents; therefore, each system shall be used independentlyof the other. Combining values from the two systems mayresult in non-conformance with the standard.1.5.1 In the engineering profession it is customary practiceto use, interchangeably, units representing both mass and fo
15、rce,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. This test method has been written using SI
16、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 nonconformance with this test method.1These t
17、est methods are under the jurisdiction ofASTM Committee D18 on Soiland Rock .Current edition approved May 1, 2011. Published July 2011. Originally approvedin 1965. Last previous edition approved in 2004 as D243504. DOI: 10.1520/D2435_D2435M-11.1*A Summary of Changes section appears at the end of thi
18、s standard.Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.1.6 Observed and calculated values shall conform to theguidelines for significant digits and rounding established inPractice D6026, unless superseded by this test method.1.6.1
19、 The method used to 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.1.7 This standard does not
20、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 prior to use.2. Referenced Documents2.1 ASTM Standards:
21、2D422 Test Method for Particle-Size Analysis of SoilsD653 Terminology Relating to Soil, Rock, and ContainedFluidsD854 Test Methods for Specific Gravity of Soil Solids byWater PycnometerD1587 Practice for Thin-Walled Tube Sampling of Soils forGeotechnical PurposesD2216 Test Methods for Laboratory Det
22、ermination of Wa-ter (Moisture) Content of Soil and Rock by MassD2487 Practice for Classification of Soils for EngineeringPurposes (Unified Soil Classification System)D2488 Practice for Description and Identification of Soils(Visual-Manual Procedure)D3550 Practice for Thick Wall, Ring-Lined, Split B
23、arrel,Drive Sampling of SoilsD3740 Practice for Minimum Requirements for AgenciesEngaged in Testing and/or Inspection of Soil and Rock asUsed in Engineering Design and ConstructionD4186 Test Method for One-Dimensional ConsolidationProperties of Saturated Cohesive Soils Using Controlled-Strain Loadin
24、gD4220 Practices for Preserving and Transporting SoilSamplesD4318 Test Methods for Liquid Limit, Plastic Limit, andPlasticity Index of SoilsD4452 Practice for X-Ray Radiography of Soil SamplesD4546 Test Methods for One-Dimensional Swell or Col-lapse of Cohesive SoilsD4753 Guide for Evaluating, Selec
25、ting, and SpecifyingBalances and Standard Masses for Use in Soil, Rock, andConstruction Materials TestingD6026 Practice for Using Significant Digits in GeotechnicalDataD6027 Practice for Calibrating Linear Displacement Trans-ducers for Geotechnical Purposes3. Terminology3.1 For definitions of techni
26、cal terms used in these testmethods, see Terminology D653.3.2 Definitions of Terms Specific to This Standard:3.2.1 axial deformation (L, L, %, or -), nthe change inaxial dimension of the specimen which can be expressed interms of length, height of specimen, strain or void ratio.3.2.2 estimated preco
27、nsolidation stress (F/L2), nthe valueof the preconsolidation stress determined by the techniqueprescribed in these test methods for the purpose of aiding thelaboratory in the performance of the test. This estimationshould not be considered equivalent to an engineering inter-pretation of the test mea
28、surements.3.2.3 load (F), nin the context of soil testing, the act ofapplying force or deformation to the boundary of a testspecimen. In the incremental consolidation test this is generallyperformed using weights on a hanger.3.2.4 load increment, none individual step of the testduring which the spec
29、imen is under a constant total axial stress.3.2.5 load increment duration (T), nthe length of time thatone value of total axial stress is maintained on the specimen.3.2.6 load increment ratio, LIR (-), nthe change (increaseor decrease) in total axial stress to be applied to the specimenin a single s
30、tep divided by the current total axial stress.3.2.6.1 DiscussionLoad Increment Ratio is historicallyused in consolidation testing to reflect the fact that the test wasperformed by adding weights to apply the total axial stress tothe specimen.3.2.7 total axial stress (F/L2), nthe force acting on thes
31、pecimen divided by the specimen area. Once consolidation iscomplete, the effective axial stress is assumed to equal the totalaxial stress.3.2.8 total axial stress increment (F/L2), nthe change(increase or decrease) in total axial stress applied in one singlestep. The change may be an increase or a d
32、ecrease in stress.4. Summary of Test Methods4.1 In these test methods a soil specimen is restrainedlaterally and loaded axially with total stress increments. Eachstress increment is maintained until excess pore water pres-sures are essentially dissipated. Pore pressure is assumed to bedissipated bas
33、ed on interpretation of the time deformationunder constant total stress. This interpretation is founded on theassumption that the soil is 100% saturated. Measurements aremade of change in the specimen height and these data are usedto determine the relationship between the effective axial stressand v
34、oid ratio or strain. When time deformation readings aretaken throughout an increment, the rate of consolidation isevaluated with the coefficient of consolidation.5. Significance and Use5.1 The data from the consolidation test are used to estimatethe magnitude and rate of both differential and total
35、settlementof a structure or earthfill. Estimates 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 redu
36、ce the potential of disturbance effects.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.D2435/D2435M 112NOTE
37、3Notwithstanding 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 suitability of theequipment and facilities used. Agencies that meet the criteria of PracticeD3740 generally are c
38、onsidered capable of competent and objectivetesting. Users of this test method are cautioned that compliance withPractice D3740 does not assure reliable testing. Reliable testing dependson many factors, and Practice D3740 provides a means of evaluation someof these factors.5.3 Consolidation test res
39、ults are dependent on the magni-tude of the load increments. Traditionally, the axial stress isdoubled for each increment resulting in a load increment ratioof 1. For intact samples, this loading procedure has provideddata from which estimates of the preconsolidation stress, usingestablished interpr
40、etation techniques, compare favorably withfield observations. Other loading schedules may be used tomodel particular field conditions or meet special requirements.For example, it may be desirable to inundate and load thespecimen in accordance with the wetting or loading patternexpected in the field
41、in order to best evaluate the response.Load increment ratios of less than 1 may be desirable for soilsthat are highly sensitive or whose response is highly dependenton strain rate.5.4 The interpretation method specified by these test meth-ods to estimate the preconsolidation stress provides a simple
42、technique to verify that one set of time readings are taken afterthe preconsolidation stress and that the specimen is loaded to asufficiently high stress level. Several other evaluation tech-niques exist and may yield different estimates of the precon-solidation stress.Alternative techniques to esti
43、mate the precon-solidation stress may be used when agreed to by the requestingagency and still be in conformance with these test methods.5.5 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
44、 24 h. For some soils,the rate of consolidation is such that complete consolidation(dissipation of excess pore pressure) will require more than 24h. The apparatus in general use does not have provisions forformal verification of pore pressure dissipation. It is necessaryto use an interpretation tech
45、nique which indirectly determinesthat consolidation is essentially complete. These test methodsspecify procedures for two techniques (Method A and MethodB), however alternative techniques may be used when agreedto by the requesting agency and still be in conformance withthese test methods.5.6 The ap
46、paratus in general use for these test methods donot have provisions for verification of saturation. Most intactsamples taken from below the water table will be saturated.However, the time rate of deformation is very sensitive todegree of saturation and caution must be exercised regardingestimates fo
47、r duration of settlements when partially saturatedconditions prevail. Inundation of the test specimen does notsignificantly change the degree of saturation of the testspecimen but rather provides boundary water to eliminatenegative pore pressure associated with sampling and preventsevaporation durin
48、g the test. The extent to which partialsaturation influences the test results may be a part of the testevaluation and may include application of theoretical modelsother than conventional consolidation theory. Alternatively, thetest may be performed using an apparatus equipped to saturatethe specimen
49、.5.7 These test methods use conventional consolidationtheory based on Terzaghis consolidation equation to computethe coefficient of consolidation, cv. The analysis is based uponthe following assumptions:5.7.1 The soil is saturated and has homogeneous properties;5.7.2 The flow of pore water is in the vertical direction;5.7.3 The compressibility of soil particles and pore water isnegligible compared to the compressibility of the soil skeleton;5.7.4 The stress-strain relationship is linear over the loadincrement;5.7.5 The ratio of soil permeability to soil compressibil
