1、Designation: D 4186 06Standard Test Method forOne-Dimensional Consolidation Properties of SaturatedCohesive Soils Using Controlled-Strain Loading1This standard is issued under the fixed designation D 4186; the number immediately following the designation indicates the year oforiginal adoption or, in
2、 the case of revision, the 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 This test method is for the determination of the magni-tude and rate-of-consolida
3、tion 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 c
4、onstant 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, and base excess pressure. Theeffective stress is computed using steady state equations.1.3 This test me
5、thod 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-t
6、ions. Section 5.4 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
7、.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 D 2435.1.7 This test method applies to intact (Group C and GroupD of Practice D 4220), remolded, or laboratory reconstitutedsamples or specimens.1.8 This te
8、st 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 consol
9、idation.1.9 All recorded and calculated values shall conform to theguide for significant digits and rounding established in PracticeD 6026.1.9.1 The procedures used to specify how data are collected/recorded and calculated in this standard are regarded as theindustry standard. In addition, they are
10、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 digi
11、ts 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 bere
12、garded a non-conformance with this standard.1.10 This standard is written using SI units. Inch-poundunits are provided for convenience. The values stated ininch-pound units may not be exact equivalents; therefore, theyshall be used independently of the SI system. Combiningvalues from the two systems
13、 may result in non-conformancewith the this standard.1.10.1 The gravitational system of inch-pound units is usedwhen dealing with inch-pound units. In this system, the pound(lbf) represents a unit of force (weight), while the unit for massis slugs. The rationalized slug unit is not given, unless dyn
14、amic(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 twoseparate systems of units; that is, the absolute system and thegravitational
15、system. It is scientifically undesirable to 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 recording1
16、This 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 Sept. 1, 2006. Published December 2006. Originallyapproved in 1982. Last previous edition approved
17、in 1998 as D 4186 89 (1998)e1.1*A Summary 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.pounds of mass (lbm) or recording density in lbm/ft3shall notbe regarded as non-conforman
18、ce with this standard.1.11 This standard may involve hazardous materials, opera-tions, 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 toestablish appropriate safety and health p
19、ractices and deter-mine the applicability of regulatory limitations prior to use.2. Referenced Documents2.1 ASTM Standards:2D 653 Terminology Relating to Soil, Rock, and ContainedFluidsD 854 Test Methods for Specific Gravity of Soil Solids byWater PycnometerD 1587 Practice for Thin-Walled Tube Sampl
20、ing of Soilsfor Geotechnical PurposesD 2216 Test Methods for Laboratory Determination of Wa-ter (Moisture) Content of Soil and Rock by MassD 2435 Test Methods for One-Dimensional ConsolidationProperties of Soils Using Incremental LoadingD 2487 Practice for Classification of Soils for EngineeringPurp
21、oses (Unified Soil Classification System)D 2488 Practice for Description and Identification of Soils(Visual-Manual Procedure)D 3550 Practice for Thick Wall, Ring-Lined, Split Barrel,Drive Sampling of SoilsD 3740 Practice for Minimum Requirements for AgenciesEngaged in the Testing and/or Inspection o
22、f Soil and Rockas Used in Engineering Design and ConstructionD 4220 Practices for Preserving and Transporting SoilSamplesD 4318 Test Methods for Liquid Limit, Plastic Limit, andPlasticity Index of SoilsD 4452 Test Methods for X-Ray Radiography of SoilSamplesD 4753 Guide for Evaluating, Selecting, an
23、d SpecifyingBalances and Standard Masses for Use in Soil, Rock, andConstruction Materials TestingD 6026 Practice for Using Significant Digits in Geotechni-cal DataD 6519 Practice for Sampling of Soil Using the Hydrauli-cally Operated Stationary Piston SamplerD 6913 Test Methods for Particle-Size Dis
24、tribution (Grada-tion) of Soils Using Sieve AnalysisD 7015 Practices for Obtaining Undisturbed Block (Cubicaland Cylindrical) Samples of Soils3. Terminology3.1 Definitions:3.1.1 For definitions of other terms used in this Test Method,see Terminology D 653.3.2 Definitions of Terms:3.2.1 back pressure
25、, (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 consolidometeran apparatus conta
26、ining a specimenunder conditions of no lateral deformation while allowingone-dimensional axial deformation and one directional axialflow.3.2.3 excess pore-water pressure, Du(FL-2)in effectivestress testing, the pressure that exists in the pore fluid relativeto (above or below) the back pressure.3.2.
27、4 total axial stress, sa(FL-2)in effective stress testing,the total stress applied to the free draining surface of thespecimen in excess of the back pressure.3.3 Definitions of Terms Specific to This Standard:3.3.1 axial displacement reading, AD (volts)readingstaken during the test of the axial disp
28、lacement transducer.3.3.2 axial force reading, AF (volts)readings taken duringthe test of the axial force transducer.3.3.3 average effective axial stress, sa(FL-2)the effec-tive stress calculated using either the linear or nonlinear theoryequations to represent the average value during constant stra
29、inrate conditions.3.3.4 base excess pressure, Dum(FL-2)the fluid pressurein excess of the back pressure that is measured at theimpervious boundary of the specimen under conditions of oneway drainage.3.3.5 base pressure, um(FL-2)the fluid pressure measuredat the impervious boundary (usually at the ba
30、se of theconsolidometer) of the specimen under conditions of one waydrainage.3.3.6 base pressure reading, BP (volts)readings takenduring the test of the base pressure transducer.3.3.7 chamber pressure, sc(FL-2)the fluid pressure insidethe consolidometer. In most CRS consolidometers, the cham-ber flu
31、id is in direct contact with the specimen. For thesedevices (and this test method), the chamber pressure will beequal to the back pressure.3.3.8 chamber pressure reading, CP (volts)readings takenduring the test of the chamber pressure transducer.3.3.9 constant rate-of-strain, CRSa method of consolid
32、at-ing a specimen in which the surface is deformed at a uniformrate while measuring the axial deformation, axial reactionforce, and induced base excess pressure.3.3.10 dissipationchange over time of an excess initialcondition to a time independent condition.3.3.11 equilibrated waterpotable water tha
33、t has come toequilibrium with the current room conditions including tem-perature, chemistry, dissolved air, and stress state.3.3.12 linear theory (calculation method)a set of equa-tions derived based on the assumption that the coefficient ofvolume compressibility (mv) is constant.3.3.13 monofilament
34、 nylon screenthin porous syntheticwoven filter fabric made of single untwisted filament nylon.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
35、 Summary page onthe ASTM website.D41860623.3.14 nonlinear theory (calculation method)a set ofequations derived based on the assumption that the compres-sion index (Cc) is constant.3.3.15 pore-water pressure factor, F (D)a dimensionlessnumber equal to the change in total axial stress minus the baseex
36、cess pressure divided by the change in total axial stress.3.3.16 pore-water pressure ratio, Ru(D)the base excesspressure divided by the total axial stress.3.3.17 steady state conditionin CRS testing, a time inde-pendent strain distribution within the specimen that changes inaverage value as loading
37、proceeds.3.3.18 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 to asteady state strain distribution.4. Summary of Te
38、st Method4.1 In this test method the specimen is constrained axiallybetween two parallel, rigid platens and laterally such that thecross sectional area remains constant. Drainage is providedalong one boundary (typically the top) and the fluid pressure ismeasured at the other sealed boundary (typical
39、ly the base).4.2 A back pressure 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,and base pressure. A standard test includes one loading phase,one const
40、ant load phase, and one unloading phase. Theconstant load phase allows the base excess pressure to return tozero prior to unloading. More extensive tests can be performedby including more phases to obtain unload-reload cycle(s).4.4 The rate of deformation is selected to produce a porepressure ratio
41、that is between 3 % and 15 % at the end of theloading phase.4.5 During loading and unloading, the measurements arefirst evaluated in order to be sure transient effects are small.Steady state equations are then used to compute the one-dimensional stress versus strain relationship. During the load-ing
42、 phase, when base excess pressures are significant, themeasurements are used to compute both the coefficient ofconsolidation and hydraulic conductivity throughout the test.5. Significance and Use5.1 Information concerning magnitude of compression andrate-of-consolidation of soil is essential in the
43、design of earthstructures and earth supported structures. The results of this testmethod may be used to analyze or estimate one-dimensionalsettlements, rates of settlement associated with the dissipationof excess pore-water pressure, and rates of fluid transport dueto hydraulic gradients.5.2 Strain
44、Rate Effects:5.2.1 It is recognized that the stress-strain results of con-solidation tests are strain rate dependent. Strain rates arelimited in this test method by specification of the pore-waterpressure ratio. This specification provides comparable resultsto the 100 % consolidation compression beh
45、avior obtainedusing Test Method D 2435.5.2.2 Field strain rates vary greatly with time, depth belowthe loaded area, and radial distance from the loaded area. Fieldstrain rates during consolidation processes are generally muchslower than laboratory strain rates and cannot be accuratelydetermined or p
46、redicted. For these reasons, it is not practical toreplicate the field strain rates with the laboratory test strainrate.5.3 This test method may not be used to measure theproperties of partially saturated soils because the methodrequires the material to be back pressure saturated prior toconsolidati
47、on.5.4 Test Interpretation AssumptionsThe equations used inthis test method are based on the following assumptions:5.4.1 The soil is saturated.5.4.2 The soil is homogeneous.5.4.3 The compressibility of the soil particles and water isnegligible.5.4.4 Flow of pore water occurs only in the vertical dir
48、ec-tion.5.4.5 Darcys law for flow through porous media applies.5.4.6 The ratio of soil hydraulic conductivity to compress-ibility is constant throughout the specimen during the timeinterval between individual readings.5.4.7 The compressibility of the base excess pressure mea-surement system is negli
49、gible compared to that of the soil.5.5 Theoretical Solutions:5.5.1 Solutions for constant rate of strain consolidation areavailable for both linear and nonlinear soil models.5.5.1.1 The linear model assumes that the soil has a constantcoefficient of volume compressibility (mv). These equations arepresented in 13.4.5.5.1.2 The nonlinear model assumes that the soil has aconstant compression index (Cc). These equations are pre-sented in Appendix X1.NOTE 1The base excess pressure measured at the boundary of thespecimen is assumed equal to the maximum excess po
