ASTM D4186-89(1998)e1
(Test Method)Standard Test Method for One-Dimensional Consolidation Properties of Soils Using Controlled-Strain Loading
Standard Test Method for One-Dimensional Consolidation Properties of Soils Using Controlled-Strain Loading
SCOPE
1.1 This test method covers the determination of the rate and magnitude of consolidation of soil when it is restrained laterally and drained axially and subjected to controlled-strain loading. Note 1-The determination of the rate and magnitude of consolidation of soil when it is subjected to incremental loading is covered by Test Method D2435.
1.2 The values stated in SI units are to be regarded as the standard. The values stated in inch-pound units are approximate.
1.3 This standard may involve hazardous materials, operations, and equipment. This standard does not purport to address all of the safety problems associated with its use. It is the responsibility of the user of this standard to establish appropriate safety and health practices and determine the applicability of regulatory limitations prior to use.
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e1
Designation:D4186–89 (Reapproved 1998)
Standard Test Method for
One-Dimensional Consolidation Properties of Soils Using
Controlled-Strain Loading
This standard is issued under the fixed designation D4186; the number immediately following the designation indicates the year of
original adoption or, in the case of revision, the year of last revision.Anumber in parentheses indicates the year of last reapproval.A
superscript epsilon (e) indicates an editorial change since the last revision or reapproval.
e NOTE—Sections 1.3 and 13, and a Summary of Changes were added editorially in January 1999.
1. Scope * D3550 Practice for Ring-Lined Barrel Sampling of Soils
D4220 Practices for Perserving and Transporting Soil
1.1 This test method covers the determination of the rate
Samples
and magnitude of consolidation of soil when it is restrained
D4318 Test Method for Liquid Limit, Plastic Limit, and
laterally and drained axially and subjected to controlled-strain
Plasticity Index of Soils
loading.
NOTE 1—The determination of the rate and magnitude of consolidation 3. Terminology
of soil when it is subjected to incremental loading is covered by Test
3.1 Definitions—The definitions of terms used in this
Method D2435.
method shall be in accordance with Terminology D653.
1.2 The values stated in SI units are to be regarded as the
3.2 Definitions of Terms Specific to This Standard:
standard. The values stated in inch-pound units are approxi-
3.2.1 back pressure—the pore–water pressure at the drain-
mate.
age boundary.
1.3 This test method is currently undergoing extensive
3.2.2 excess pore-water pressure, u —the pore-water pres-
b
review.
sure developed at the impervious end of the specimen (usually
1.4 This standard may involve hazardous materials, opera-
the base of the specimen) in excess of the back pressure.
tions, and equipment. This standard does not purport to
3.2.3 applied vertical stress, s —the axial stress applied at
v
address all of the safety problems associated with its use. It is
the drainage boundary in excess of the back pressure.
the responsibility of the user of this standard to establish
3.2.4 pore pressure ratio—the excess pore water pressure
appropriate safety and health practices and determine the
divided by the applied vertical stress.
applicability of regulatory limitations prior to use.
4. Significance and Use
2. Referenced Documents
4.1 Information concerning rate and magnitude of consoli-
2.1 ASTM Standards:
dation settlement of soil is essential in the design of earth and
D422 Test Method for Particle-Size Analysis of Soils
earth-supported structures. The results of this method may be
D653 Terminology Relating to Soil, Rock, and Contained
used to analyze or estimate one-dimensional consolidation
Fluids
settlements and rates.
D854 Test Method for Specific Gravity of Soils
4.2 Strain Rate:
D1587 Practice for Thin-Walled Tube Sampling of Soils
4.2.1 It is recognized that consolidation test results are
D2216 TestMethodforLaboratoryDeterminationofWater
strain-rate dependent. Strain rates recommended in this stan-
(Moisture) Content of Soil, Rock, and Soil-Aggregate
dard are within the range usually encountered in Test Method
Mixtures
D2435.
D2435 Test Method for One-Dimensional Consolidation
4.2.2 Field strain rates vary greatly with time, depth below
Properties of Soils
the loaded area, and radial distance from the loaded area.
Because field rates cannot be accurately determined or pre-
dicted, it is not feasible to relate the laboratory-test strain rate
This test method is under the jurisdiction of ASTM Committee D-18 on Soil
to the field strain rate. However, it may be feasible to relate
and Rock and is the direct responsibility of Subcommittee D18.05 on Structural
field pore pressure ratios (u s ) to laboratory pore pressure
Properties of Soils.
b v
Current edition approved June 30, 1989. Published October 1989. Originally
ratios. Further research is needed in this area.
published as D4186–82. Last previous edition D4186–82.
Annual Book of ASTM Standards, Vol 04.08.
*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.
D4186
4.2.3 The constant-rate-of-strain consolidation test does not of measuring the pore-water pressure at the base of the
address the problem of strain-rate effects but does provide a specimentoanaccuracyof0.25%ofthemaximumanticipated
means for studying strain rate effects.
pore pressure.
4.3 This method is not applicable to soils of high perme-
5.4 Back Pressure-Maintaining Device, capable of applying
ability, such as sands and other coarse-grained soils, or to
and controlling the back pressure to within6 2.0%. This
partially saturated soils.
device may consist of a reservoir, it may have reservoirs
4.4 This method makes the following assumptions:
connected to the top and bottom of the specimen and partially
4.4.1 Theratioofsoilpermeabilitytosoilcompressibilityis
filled with de-aired water; the upper part of the reservoir shall
constant,
be connected to a compressed gas supply, the gas pressure
4.4.2 Flow of soil pore water occurs only in the vertical
being controlled by a pressure regulator and measured by a
direction,
pressure gage. (See Note 3.) However, a hydraulic system
4.4.3 Darcy’s law for flow through porous media applies,
pressurized by a deadweight acting on a piston or any other
4.4.4 The soil is saturated,
pressure-maintaining device capable of applying and control-
ling the back pressure to the tolerance prescribed in this
4.4.5 The soil is homogeneous,
paragraph may be used. A low volume-change valve shall be
4.4.6 The compressibility of the soil grains and water is
provided in the back-pressure measuring device as near as
negligible,
possible to the base of the specimen. This valve, when open,
4.4.7 The log stress versus strain relationship is linear
shall permit the application of back pressure to the base of the
during a short-time interval of loading, and
specimen; when closed, shall prevent the drainage of water
4.4.8 The distribution of excess pore-water pressures across
from the specimen base and pore-water pressure-measuring
the specimen is parabolic.
devicetothereservoirofthebackpressure-maintainingdevice.
5. Apparatus
NOTE 3—Allgas-waterinterfacesshouldbesmallinarearelativetothe
5.1 Axial Loading Device—The axial compression device
area of the specimen and should be in reservoirs connected to the
consolidometer by a length of small diameter tubing.
may be a screw jack driven by an electric motor through a
geared transmission, a platform weighing scale equipped with
5.5 Deformation Indicator—The deformation indicator
a screw-jack activated yoke, a hydraulic or pneumatic loading
shall be a dial indicator or displacement transducer having a
device, or any other compression device with sufficient capac-
sensitivity of 0.002 mm (0.0001 in.) and a range of at least
ityandcontroltoaxiallycompressthespecimenattheconstant
50% of the specimen height, or other measuring device
rate of strain prescribed in 9.6. If the axial loading device is
meeting these requirements for sensitivity and range.
outside the consolidometer, see 5.8.
5.6 Timer, indicating the elapsed testing time to the nearest
5.2 Axial Load-Measuring Device—The axial load-
1 s for establishing the rates of strain application prescribed in
measuring device may be a load ring, strain-gage load cell,
9.6.
hydraulicloadcell,oranyotherload-measuringdevicecapable
5.7 Balances, devices for determining the mass of the soil
of the accuracy prescribed in this paragraph and may be a part
specimens as well as portions of the apparatus. All measure-
of the axial loading device. The axial load-measuring device
ments of mass should be accurate to 0.1%.
shall be capable of measuring the axial load to an accuracy of
0.25% of the maximum load applied to the specimen.
5.8 Consolidometer, to hold the specimen in a ring that is
fixed to a rigid base, with porous stones on each face of the
NOTE 2—For a constant rate of deformation to be transmitted from the
specimen.Any potentially submerged parts of the consolidom-
axial loading device through the load-measuring device, it is important
eter shall be made of a material that is noncorrosive in relation
that the load-measuring device be relatively stiff. Some hydraulic load
cells or proving rings may not provide sufficient stiffness. to the soil or other parts of the consolidometer. The bottom of
the ring shall form a leakproof seal with the rigid base capable
5.3 Pore-Water Pressure-Measuring Device—The pore-
of withstanding internal pressures of 1400 kPa (200 psi). The
waterpressure-measuringdeviceshallbeadifferentialpressure
consolidometer shall be constructed such that placement of the
transducer. Separate pressure transducers for measuring pore-
specimenintotheringandconsolidometerwillnotentrapairat
water pressure at the base of the specimen and back pressures
the base of the specimen. The axial loading device and back
may be used if both have the required accuracy and both are
pressure-maintaining device may be an integral part of the
monitored during the test. The device shall be constructed and
consolidometer.Ifthedesignoftheconsolidometerissuchthat
located such that the pore-water pressure at the base of the
back pressures affect axial load readings (due to pressure
specimen can be measured with negligible drainage of pore
pushing the piston from the consolidometer), the change in
water from the base of the specimen on one side of the
readings with changes in back pressure shall be determined by
transducer. The other side of the transducer measures the back
calibration.Theconsolidometershallconformtothefollowing
pressure applied to the specimen. Negligible drainage of pore
requirements:
water from the base of the specimen can be attained if the
5.8.1 Minimum Specimen Diameter shall be 50 mm (2.0
coefficient of volume change of the pore pressure-measuring
deviceandde-aired,water-filledcavitiesconnectingthedevice in.) and shall be at least 6 mm (0.25 in.) less than the diameter
−5 3 −8
of the sample tube if using undisturbed samples, except as
to the base of the specimen is less than 10 in. /psi (10
m /Pa). The pore pressure-measuring device shall be capable indicated in 7.2.
D4186
5.8.2 Minimum Specimen Thickness shall be 20 mm (0.75 of the ring.The surface must be smooth.Aspecimen ring with
in.) but shall be not less than 10 times the maximum grain thecuttingedgeattachedprovidesthemostaccuratefitinmost
diameter as determined in accordance with Method D422. soils.
5.8.3 Minimum-Specimen-Diameter-to-Thickness Ratio- 7.2 Organic soils, such as peat, and those soils that are
shall be 2.5. easily damaged, may be transferred directly from the sampling
5.8.4 Thickness of the Ring shall be such that, under as- tube to the ring where the ring and tube sizes have been
sumed hydrostatic stress conditions in the specimen, the selected for this purpose, provided that the cutting edge of the
changeindiameteroftheringwillnotexceed0.03%underthe ring has the same diameter as the sample.
greatest load applied. 7.3 Determine the mass and height of the specimen. Record
5.8.5 Ring shall be made of a material that is noncorrosive the specimen mass, height, and diameter.
in relation to the soil and pore fluid being tested. The inner
NOTE 4—Precautions should be taken to minimize disturbance of the
surface shall be highly polished or shall be coated with a
soil or changes in moisture and density during specimen preparation;
low-friction material.
vibration, distortion, and compression must be avoided.
5.9 Porous Disk:
7.4 Use the material trimmed adjacent to the specimen (see
5.9.1 The porous stones shall be of silicon carbide, alumi-
7.1) to determine the natural moisture content (based on dry
numoxide,metal,orothersuitablematerialthatisnotattacked
mass) in accordance with Method D2216 and the specific
by the soil or soil moisture and shall be of medium grade. For
gravity in accordance with Test Method D854. Determine
soft fine-grain soils, a fine-grade porous stone shall be used.
initial wet weight of the specimen and its volume from the
Thestoneshallbefineenoughthatthesoilwillnotextrudeinto
mass, diameter, and height of the specimen ring. A more
the pores, but have sufficient permeability so as not to impede
accurate determination of the specimen dry weight and mois-
the flow of water from the specimen. (Exact criteria have not
ture is found by drying the specimen at the end of the test (see
been established.)
9.11).Thevaluedeterminedfromthetrimmingsisapproximate
5.9.2 The diameter of the top stone shall be 0.2 to 0.5 mm
but permits determining the void ratio before the test is
(0.01 to 0.02 in.) less than that of the ring.
complete. The specific gravity can be estimated where an
5.9.3 The stone shall be thick enough to prevent breaking.
accurate void ratio is not needed.
The top stone shall be loaded through a corrosion-resistant
7.5 The liquid and plastic limits as determined by Test
plate of sufficient rigidity to prevent breakage of the stone.
Method D4318, are useful in identifying the soil and in
5.10 Moist Room—In climates where moisture loss during
correlating the results of tests on different soils. These tests
preparation exceeds 0.1%, the specimen shall be prepared in a
may also be performed on the trimmings.
moist room.
5.11 Trimmer or Cylindrical Cutter, for trimming the speci-
8. Preparation of Apparatus
men down to the inside diameter of the consolidometer ring
8.1 De-airthewaterinthebackpressure-maintainingdevice
with a minimum of disturbance.
and pore-water pressure-measuring system (see 5.3 and 5.4).
5.12 Specimen-Measuring Device, capable of measuring
8.2 Saturate the porous stones with de-aired water.
specimen height and diameter to the nearest 0.02 mm (0.001
8.3 Place the bottom porous stone in the consolidometer so
in.).
as not to entrap any air in the pore water pressure-measuring
5.13 DryingOven,thatcanbemaintainedat230 69°F(110
system.
6 5°C).
NOTE 5—Guidelinesforsystemsaturationmaybefoundinoneormore
5.14 Miscellaneous Equipment—Specimen trimming and
of the references listed at the end of this method.
carving tools, including spatulas, knives, and wire saws,
moisture content cans, and data sheets as required.
9. Procedure
9.1 Assemble the specimen, ring, porous stones, and load-
6. Sampling
ing plate in the consolidometer. Avoid entrapping any air
6.1 Sampling and field investigation shall be conducted in
between the bottom porous stone and the specimen.
accordance with Practice D1587. Specimens cut from block
9.2 Place the consolidometer in the axial l
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