ASTM_D_4186_-_D_4186M_-_12e1.pdf

Designation:D4186/D4186M121Standard 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 adoption 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 for 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.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.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 steady 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 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 GroupD 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 but 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 throughout 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 addition,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 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 standard 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 independentlyof 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 unit 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 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.*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 States1 separate systems of units;that is,the absolute system and thegravitational system.It is