1、Designation: D4186/D4186M 121Standard Test Method forOne-Dimensional Consolidation Properties of SaturatedCohesive Soils Using Controlled-Strain Loading1This standard is issued under the fixed designation D4186/D4186M; the number immediately following the designation indicates theyear of original ad
2、option or, in the case of 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.1NOTEEditorially corrected Eq X1.3 in June 2014.1. Scope*1.1 This test method is f
3、or the determination of the magni-tude and rate-of-consolidation of saturated cohesive soils usingcontinuous controlled-strain axial compression. The specimenis restrained laterally and drained axially to one surface. Theaxial force and base excess pressure are measured during thedeformation process
4、. Controlled strain compression is typicallyreferred to as constant rate-of-strain (CRS) testing.1.2 This test method provides for the calculation of total andeffective axial stresses, and axial strain from the measurementof axial force, axial deformation, chamber pressure, and baseexcess pressure.
5、The effective stress is computed using steadystate equations.1.3 This test method provides for the calculation of thecoefficient of consolidation and the hydraulic conductivitythroughout the loading process. These values are also based onsteady state equations.1.4 This test method makes use of stead
6、y state equationsresulting from a theory formulated under particular assump-tions. Section 5.5 presents these assumptions.1.5 The behavior of cohesive soils is strain rate dependentand hence the results of a CRS test are sensitive to the imposedrate of strain. This test method imposes limits on the
7、strain rateto provide comparable results to the incremental consolidationtest (Test Method D2435).1.6 The determination of the rate and magnitude of consoli-dation of soil when it is subjected to incremental loading iscovered by Test Method D2435.1.7 This test method applies to intact (Group C and G
8、roupD of Practice D4220), remolded, or laboratory reconstitutedsamples.1.8 This test method is most often used for materials ofrelatively low hydraulic conductivity that generate measurableexcess base pressures. It may be used to measure the compres-sion behavior of essentially free draining soils b
9、ut will notprovide a measure of the hydraulic conductivity or coefficientof consolidation.1.9 All recorded and calculated values shall conform to theguide for significant digits and rounding established in PracticeD6026, unless superseded by this test method. The significantdigits specified througho
10、ut this standard are based on theassumption that data will be collected over an axial stress rangefrom 1% of the maximum stress to the maximum stress value.1.9.1 The procedures used to specify how data are collected/recorded and calculated in this standard are regarded as theindustry standard. In ad
11、dition, they are representative of thesignificant digits that should generally be retained. The proce-dures used do not consider material variation, purpose forobtaining the data, special purpose studies, or any consider-ations for the users objectives; and it is common practice toincrease or reduce
12、 significant digits of reported data to becommensurate with these considerations. It is beyond the scopeof this standard to consider significant digits used in analysismethods for engineering design.1.9.2 Measurements made to more significant digits orbetter sensitivity than specified in this standa
13、rd shall not beregarded a non-conformance with this standard.1.10 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 system may not be exactequivalents; therefore, each system shall be used independently
14、of the other. Combining values from the two systems mayresult in non-conformance with the standard.1.10.1 The gravitational system is used when working withinch-pound units. In this system, the pound (lbf) represents aunit of force (weight), while the unit for mass is slugs. Therationalized slug uni
15、t is not given, unless dynamic (F = ma)calculations are involved.1.10.2 It is common practice in the engineering/constructionprofession to concurrently use pounds to represent both a unitof mass (lbm) and of force (lbf). This implicitly combines two1This test method is under the jurisdiction ofASTM
16、Committee D18 on Soil andRock and is the direct responsibility of Subcommittee D18.05 on Strength andCompressibility of Soils.Current edition approved Nov. 1, 2012. Published December 2012. Originallyapproved in 1982. Last previous edition approved in 2006 as D4186 06. DOI:10.1520/D4186_D4186M-12E01
17、.*A Summary of Changes section appears at the end of this standardCopyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States1separate systems of units; that is, the absolute system and thegravitational system. It is scientifically undesirable to
18、 combinethe use of two separate sets of inch-pound units within a singlestandard. As stated, this standard includes the gravitationalsystem of inch-pound units and does not use/present the slugunit for mass. However, the use of balances or scales recordingpounds of mass (lbm) or recording density in
19、 lbm/ft3shall notbe regarded as non-conformance with this standard.1.11 This standard may involve hazardous materials,operations, and equipment. This standard does not purport toaddress all of the safety concerns, if any, associated with itsuse. It is the responsibility of the user of this standard
20、toestablish appropriate safety and health practices and deter-mine the applicability of regulatory limitations prior to use.2. Referenced Documents2.1 ASTM Standards:2D653 Terminology Relating to Soil, Rock, and ContainedFluidsD854 Test Methods for Specific Gravity of Soil Solids byWater PycnometerD
21、1587 Practice for Thin-Walled Tube Sampling of Soils forGeotechnical PurposesD2216 Test Methods for Laboratory Determination of Water(Moisture) Content of Soil and Rock by MassD2435 Test Methods for One-Dimensional ConsolidationProperties of Soils Using Incremental LoadingD2487 Practice for Classifi
22、cation of Soils for EngineeringPurposes (Unified Soil Classification System)D2488 Practice for Description and Identification of Soils(Visual-Manual Procedure)D3213 Practices for Handling, Storing, and Preparing SoftIntact Marine SoilD3550 Practice for Thick Wall, Ring-Lined, Split Barrel,Drive Samp
23、ling of SoilsD3740 Practice for Minimum Requirements for AgenciesEngaged in Testing and/or Inspection of Soil and Rock asUsed in Engineering Design and ConstructionD4220 Practices for Preserving and Transporting SoilSamplesD4318 Test Methods for Liquid Limit, Plastic Limit, andPlasticity Index of So
24、ilsD4452 Practice for X-Ray Radiography of Soil SamplesD4753 Guide for Evaluating, Selecting, and Specifying Bal-ances and Standard Masses for Use in Soil, Rock, andConstruction Materials TestingD5720 Practice for Static Calibration of ElectronicTransducer-Based Pressure Measurement Systems forGeote
25、chnical PurposesD6026 Practice for Using Significant Digits in GeotechnicalDataD6027 Practice for Calibrating Linear Displacement Trans-ducers for Geotechnical Purposes (Withdrawn 2013)3D6519 Practice for Sampling of Soil Using the Hydrauli-cally Operated Stationary Piston SamplerD6913 Test Methods
26、for Particle-Size Distribution (Grada-tion) of Soils Using Sieve AnalysisD7015 Practices for Obtaining Intact Block (Cubical andCylindrical) Samples of Soils3. Terminology3.1 Definitions:3.1.1 For definitions of technical terms used in this TestMethod, see Terminology D653.3.2 Definitions of Terms:3
27、.2.1 back pressure, (ub(FL-2)a fluid pressure in excessof atmospheric pressure that is applied to the drainage bound-ary of a test specimen.3.2.1.1 DiscussionTypically, the back pressure is appliedto cause air in the pore spaces to pass into solution, thussaturating the specimen.3.2.2 consolidometer
28、an apparatus containing a specimenunder conditions of negligible lateral deformation while allow-ing one-dimensional axial deformation and one directionalaxial flow.3.2.3 excess pore-water pressure, u(FL-2)in effectivestress testing, the pressure that exists in the pore fluid relativeto (above or be
29、low) the back pressure.3.2.4 total axial stress, a(FL-2)in effective stress testing,the normal stress applied to the axial boundary of the specimenin excess of the back pressure.3.3 Definitions of Terms Specific to This Standard:3.3.1 average effective axial stress, a(FL-2)the effectivestress calcul
30、ated using either the linear or nonlinear theoryequations to represent the average value at any time understeady state constant strain rate conditions.3.3.2 axial deformation reading, AD (volts) readingstaken during the test of the axial deformation transducer.3.3.3 axial force reading, AF (volts)re
31、adings taken duringthe test of the axial force transducer.3.3.4 base excess pressure, um(FL-2)the fluid pressurein excess (above or below) of the back pressure that ismeasured at the sealed boundary of the specimen underconditions of one way drainage. The base excess pressure willbe positive during
32、loading and negative during unloading.3.3.5 base excess pressure ratio, Ru(D) the ratio of (1) thebase excess pressure to (2) the total axial stress. This value willbe positive during loading and negative during unloading.3.3.6 base excess pressure reading, BEP (volts)readingstaken during the test o
33、f the base excess pressure transducerwhen using a differential pressure transducer which is refer-enced to the chamber pressure.2For referenced ASTM standards, visit the ASTM website, www.astm.org, orcontact ASTM Customer Service at serviceastm.org. For Annual Book of ASTMStandards volume informatio
34、n, refer to the standards Document Summary page onthe ASTM website.3The last approved version of this historical standard is referenced onwww.astm.org.D4186/D4186M 12123.3.7 base pressure, um(FL-2)the fluid pressure measuredat the sealed boundary (usually at the base of the consolidom-eter) of the s
35、pecimen under conditions of one way drainage.3.3.8 base pressure reading, BP (volts)readings takenduring the test of the base pressure transducer.3.3.9 chamber pressure, c(FL-2)the fluid pressure insidethe consolidometer. In most CRS consolidometers, the cham-ber fluid is in direct contact with the
36、specimen. For thesedevices (and this test method), the chamber pressure will beequal to the back pressure.3.3.10 chamber pressure reading, CP (volts)readingstaken during the test of the chamber pressure transducer.3.3.11 constant rate-of-strain, CRSa method of consoli-dating a specimen in which the
37、surface is deformed at auniform rate while measuring the axial deformation, axialreaction force, and induced base excess pressure.3.3.12 dissipationchange over time of an excess initialcondition to a time independent condition.3.3.13 equilibrated watertest water that has come toequilibrium with the
38、current room conditions includingtemperature, chemistry, dissolved air, and stress state.3.3.14 linear theory (calculation method)a set of equa-tions derived based on the assumption that the coefficient ofvolume compressibility (mv) is constant (the soil follows alinear strain versus effective stres
39、s relationship).3.3.15 monofilament nylon screenthin porous syntheticwoven fabric made of single untwisted filament nylon.3.3.16 nonlinear theory (calculation method) a set ofequations derived based on the assumption that the compres-sion index (Cc) is constant (the soil follows a linear strainversu
40、s log effective stress relationship).3.3.17 steady state conditionin CRS testing , a timeindependent strain distribution within the specimen thatchanges in average value as loading proceeds.3.3.18 steady state factor, F (D)a dimensionless numberequal to the change in total axial stress minus the bas
41、e excesspressure divided by the change in total axial stress.3.3.19 transient conditionin CRS testing, a time depen-dent variation in the strain distribution within the specimen thatis created at the start of a CRS loading or unloading phase orwhen the strain rate changes and then decays with time t
42、o asteady state strain distribution.3.3.20 unit conversion factora constant used in an equa-tion to unify the system of units (eg, SI to inch pound) or prefixof variables (eg. cm to m) within the same system of units.4. Summary of Test Method4.1 In this test method the specimen is constrained axiall
43、ybetween two parallel, rigid boundaries and laterally such thatthe cross sectional area remains essentially constant. Drainageis provided along one boundary (typically the top) and the fluidpressure is measured at the other sealed boundary (typically thebase) of the consolidometer.4.2 A back pressur
44、e is applied to saturate both the specimenand the base pressure measurement system.4.3 The specimen is deformed axially at a constant ratewhile measuring the time, axial deformation, reaction force,chamber pressure, and base pressure. A standard test includesone loading phase, one constant load phas
45、e, and one unloadingphase. The constant load phase allows the base excess pressureto return to near zero prior to unloading. More extensive testscan be performed by including more phases to obtain unload-reload cycle(s).4.4 The rate of deformation is selected to produce a baseexcess pressure ratio t
46、hat is between about3%and15%attheend of the loading phase.NOTE 1The base excess pressure ratio typically decreases duringloading. The lower limit provides sufficient pressure to compute the rateparameters and the upper limit reduces the differences between the linearand non linear model calculations
47、. It also helps constrain differences in thecompression behavior when testing rate sensitive materials.4.5 During loading and unloading, the measurements arefirst evaluated in order to be sure transient effects are small asdefined by the steady state factor. Steady state equations arethen used to co
48、mpute the one-dimensional effective axial stressversus strain relationship. During the loading phase, when baseexcess pressures are significant and transient effects are small,the measurements are used to compute both the coefficient ofconsolidation and hydraulic conductivity throughout the test.4.6
49、 It is possible to interpret measurements made during thetest when transient effects are significant but these equationsare complicated and beyond the scope of this standard testmethod. Interpretation of transient conditions does not consti-tute non-conformance of this test method.5. Significance and Use5.1 Information concerning magnitude of compression andrate-of-consolidation of soil is essential in the design of earthstructures and earth supported structures. The results of this testmethod may be used to analyze or estimate one-dimension
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