ASTM D6635-01

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Designation: D 6635 – 01
Standard Test Method for
Performing the Flat Plate Dilatometer
This standard is issued under the fixed designation D 6635; the number immediately following the designation indicates the year of
original adoption or, in the case of revision, the year of last revision. A number in parentheses indicates the year of last reapproval. A
superscript epsilon (e) indicates an editorial change since the last revision or reapproval.
1. Scope 2. Referenced Documents
1.1 This test method describes an in-situ penetration plus 2.1 ASTM Standards:
expansion test. The test is initiated by forcing the steel, flat D 653 Terminology Relating to Soil, Rock and Contained
2 3
plate, dilatometer blade , with its sharp cutting edge, into a Fluids
soil. Each test consists of an increment of penetration, gener- D 1586 Test Method for Penetration Test and Split-Barrel
ally vertical, followed by the expansion of a flat, circular, Sampling of Soils
metallic membrane into the surrounding soil. The test provides D 2435 Test Method for One-Dimensional Consolidation
information about the soil’s in-situ stratigraphy, stress, Properties of Soil
strength,compressibility,andpore-waterpressureforuseinthe D 3441 Test Method for Mechanical Cone PenetrationTests
design of earthworks and foundations. of Soil
1.2 This method includes specific requirements for the D 3740 Minimum Requirements for Agencies Engaged in
preliminary reduction of dilatometer test data. It does not the Testing and/or Inspection of Soil and Rock as Used in
specify how to assess or use soil properties for engineering Engineering Design and Construction
design. D 5778 Test Method for Performing Electronic Friction
1.3 This method applies best to those sands, silts, clays, and Cone and Piezocone Penetration of Soils
organicsoilsthatcanbereadilypenetratedwiththedilatometer
3. Terminology
blade, preferably using static push (see 4.2). Test results for
soils containing primarily gravel-sized particles and larger may 3.1 Definitions of Terms Specific to This Standard:
3.1.1 A-pressure—the gage gas pressure against the inside
not be useful without additional research.
1.4 This method is not applicable to soils that cannot be of the membrane when the center of the membrane has lifted
above its support and moved laterally 0.05-mm (tolerance
penetrated by the dilatometer blade without causing signifi-
+0.02, -0.00 mm) into the soil surrounding the blade.
cant damage to the blade or its membrane.
1.5 The American Society for Testing and Materials takes 3.1.2 B-pressure—the gage gas pressure against the inside
of the membrane when the center of the membrane has lifted
no position respecting the validity of any patent rights asserted
in connection with any item mentioned in this standard. Users above its support and moved laterally 1.10-mm (6 0.03 mm)
into the soil surrounding the blade.
of this standard are expressly advised that determination of the
validity of any such patent rights, and the risk of infringement 3.1.3 C-pressure—The gage gas pressure against the inside
of the membrane when the center of the membrane returns to
of such rights, are entirely their own responsibility.
1.6 This standard does not purport to address all of the the A-pressure position during a controlled, gradual deflation
following the B-pressure.
safety concerns, if any, associated with its use. It is the
responsibility of the user of this standard to establish appro- 3.1.4 DMT—abbreviation for the flat plate dilatometer test
as described herein.
priate safety and health practices and determine the applica-
bility of regulatory limitations prior to use. 3.1.5 DMT sounding—the entire sequence of dilatometer
tests and results along a vertical line of penetration in the soil.
3.1.6 DMT test—the complete procedure of penetration,
ThistestmethodisunderthejurisdictionofASTMCommitteeD18onSoiland
membrane inflation and then deflation for a single test depth
Rock and is the direct responsibility of Subcommittee D18.02 on Sampling and
using the fiat plate dilatometer.
Related Field Testing for Soil Evaluations.
Current edition approved Feb. 10, 2001. Published November 2001.
3.1.7 DA—the gage gas pressure inside the membrane
The dilatometer is covered by a patent held by Dr. Silvano Marchetti, Via
(corrected for Z ) required to overcome the stiffness of the
m
Bracciano 38, 00189, Roma, Italy. Interested parties are invited to submit informa-
tionregardingtheidentificationofacceptablealternativestothispatenteditemtothe
Committee on Standards, ASTM Headquarters, 100 Barr Harbor Drive, West
Conshohocken, PA 19428–2959. Your comments will receive careful consideration Annual Book of ASTM Standards, Vol 04.08.
at the meeting of the responsible technical committee, which you may attend. Annual Book of ASTM Standards, Vol 04.09.
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.
D 6635
membrane and move it inward to a center-expansion of 0.05 the thrust to accomplish this penetration and then using gas
mm (a negative gage or suction pressure, but recorded as pressure to expand a circular steel membrane located on one
positive) with only ambient atmospheric pressure acting exter- side of the blade. The operator measures and records the
nally. pressure required to produce expansion of the membrane into
3.1.8 DB—the gage gas pressure inside the membrane the soil at two preset deflections.The operator then deflates the
(corrected for Z ) required to overcome the stiffness of the membrane, possibly recording an optional third measurement,
m
membrane and move it outward to a center-expansion of 1.10 advances the blade the desired penetration increment and
mm against only the ambient atmospheric pressure. repeats the test. Each test sequence typically requires about 2
3.1.9 E —the dilatometer modulus, based on linear elastic minutes.Adilatometer sounding consists of the results from all
D
theory, and the primary index used in the correlation for the the tests at one location presented in a fashion indicating
constrained and Young’s moduli (see Section 9). variation with depth.
3.1.10 G —bulk specific gravity = moist soil unit weight 4.2 The operator may advance the blade using either a
m
divided by the unit weight of water.
quasi-staticpushforceordynamicimpactfromahammer,with
3.1.11 I —the dimensionless dilatometer material index, quasi-static push preferred. A record of the penetration resis-
D
used to identify soil type and delineate stratigraphy (see
tance (thrust force or blows per penetration increment) is
Section 9).
desirable both for control of the penetration and later analyses.
3.1.12 K —the dimensionless dilatometer horizontal stress
D
NOTE 1—In soils sensitive to impact and vibrations, such as medium to
index, the primary index used in the correlation for in-situ
loosesandsorsensitiveclays,dynamicinsertionmethodscansignificantly
horizontal stress, overconsolidation ratio, and undrained shear
change the test results compared to those obtained using a quasi-static
strengthincohesivesoils.K issimilartotheat-restcoefficient
push.Ingeneral,structurallysensitivesoilswillappearmorecompressible
D
of earth pressure except that it includes blade penetration when tested using dynamic insertion methods. In such cases check for
dynamic effects and, if important, calibrate and adjust test interpretations
effects.
accordingly.
3.1.13 membrane—a thin, flexible, 60-mm diameter circu-
lar piece of sheet metal (usually stainless steel), fixed around
4.3 The penetration increment typically used in a dilatom-
its edges, that mounts on one side of the dilatometer blade and
etertest(DMT)soundingvariesfrom0.15to0.30m(0.5to1.0
which, as a result of an applied internal gas pressure, expands
ft). Most soundings are performed vertically and this Test
into the soil in an approximate spherical shape along an axis
Method requires that the membrane face the horizontal direc-
perpendicular to the plane of the blade.
tion. Testing below impenetrable layers will require preboring
3.1.14 P—the total push, or thrust force required to advance
and supporting (if required) a borehole with a diameter of at
only the dilatometer blade to its test depth, measured at its test
least 100 mm (4 in.).
depthandexclusiveofsoilorotherfrictionalongthepushrods.
4.4 The operator performs a membrane calibration before
3.1.15 p —the A-pressure reading, corrected for Z , the DA
0 m
and after each DMT sounding.
membrane stiffness at 0.05-mm expansion, and the 0.05-mm
4.5 The field data is then interpreted to obtain profiles of
expansion itself, to estimate the total soil stress acting normal
those engineering soil properties of interest over the depth
to the membrane immediately before its expansion into the soil
range of the DMT sounding.
(0.00-mm expansion, see Section 9).
3.1.16 p —the B-pressure reading corrected for Z and the
1 m
5. Significance and Use
DB membrane stiffness at 1.10-mm expansion to give the total
5.1 Soundings performed using this test method provide a
soil stress acting normal to the membrane at 1.10-mm mem-
detailed record of dilatometer results which are useful for
brane expansion (see Section 9).
evaluation of site stratigraphy, homogeneity, depth to firm
3.1.17 p —The C-pressure reading corrected for Z and the
2 m
layers, voids or cavities, and other discontinuities. The pen-
DA membrane stiffness at 0.05-mm expansion and used to
etration resistance and subsequent membrane expansion are
estimate pore-water pressure (see 9.3).
used for soil classification and correlation with engineering
3.1.18 s8 —vertical effective stress at the center of the
v
properties of soils. When properly performed at suitable sites,
membrane before the insertion of the DMT blade.
the test provides a rapid means of characterizing subsurface
3.1.19 s —total vertical stress at the center of the mem-
v
conditions.
brane before the insertion of the DMT blade, generally
5.2 The DMT test provides measurements of penetration
calculated from unit weights estimated using the DMT results.
resistance, lateral stress, deformation modulus and pore-water
3.1.20 u —the pore-water pressure acting at the center of
pressure (in sands). However, the in-situ soil properties are
the membrane before the insertion of the DMT blade (often
affected by the penetration of the blade. Therefore, published
assumed as hydrostatic below the water table surface).
correlations are used to estimate soil properties for the design
3.1.21 Z —the gage pressure deviation from zero when
m
and construction of earthworks and foundations for structures,
vented to atmospheric pressure (an offset used to correct
and to predict the behavior of soils subjected to static or
pressure readings to the true gage pressure).
dynamic loads.
4. Summary of Test Method
5.3 This test method tests the soil in-situ and soil samples
4.1 A dilatometer test (DMT) consists of forcing the are not obtained. However, the interpretation of the results
dilatometer blade into the soil, with the membrane facing the from this test method does provide an estimate of the types of
horizontal direction, to a desired test penetration, measuring soil penetrated. Soil samples from parallel borings may be
D 6635
obtained for correlation purposes, but prior information or standard penetration test (SPT, see Test Method D 1586 and
experience may preclude the need for borings. Note 1), or inserted using other suitable equipment. Drill rig
support may be required to born through impenetrable soil or
6. Apparatus
rock layers above the desired test depth.
6.1 TheannotatedFig.1illustratesthemajorcomponentsof
6.3 Push rods are required to transfer the thrust from the
the DMT equipment, exclusive of that required to insert the
surface insertion equipment and to carry the pneumatic-
blade. The dimensions, tolerances, deflections, etc. have been
electrical cable from the surface control unit to the dilatometer
set by the inventor, and holder of the dilatometer patent, S.
blade. The rods are typically those used with the CPT (Test
Marchetti.
Method D 3441/D 5778) or SPT (Test Method D 1586) equip-
6.1.1 Blade, (1), 96 mm wide (95 to 97 mm) and 15 mm
ment. Suitable adapters are required to attach the blade to the
thick (13.8 to 15 mm).
bottom of the rod string and allow the cable to exit near the top
6.1.2 Membrane, (2), 60 mm diameter.
of the rods. When testing from the bottom of a borehole, the
6.1.3 Control Unit, with a pressure readout system (3) that
cablemayexitfromtherodstringsomesuitabledistanceabove
can vary in type, range, and sensitivity as required. Gages with
the blade and then be taped to the outside of the rods at
an accuracy better than ⁄4 percent of span are recommended.
appropriate intervals.The exposed cable should not be pinched
The unit shown has both low-range and high-range Bourdon
or allowed to penetrate the soil.
gages that are read manually. Older units have a single
6.4 Agas pressure tank with a suitable regulator and tubing
Bourdon gage, typically medium-range. The gages should be
to connect it to the control unit is required. The operator may
annually calibrated against a traceable standard, more often if
use any nonflammable, noncorrosive, nontoxic gas as a pres-
heavily used.The control unit also includes connections (5) for
sure source. Dry nitrogen is recommended.
a pressure source, a pneumatic-electrical cable, and an electri-
cal ground cable, and has valves to control gas flow and vent
6.5 Asuitable load cell, just above the blade or at the top of
the system (6).
the rods, is required to measure the thrust P applied during the
6.1.4 Calibration Syringe, (4) for determining the DA and
blade penetration. Hydraulic ram pressure may also be used to
DB membrane calibrations using the low-range Bourdon gage.
measure thrust with proper correlation. Parasitic soil-rod fric-
Some control units have a separate low-range pressure gage
tion is generally insignificant in sands, but may be measured
which attaches to the control unit for determining the DA and
during upward withdrawal.
DB membrane calibrations
6.1.5 Pneumatic-Electrical Cable, (7) to transmit gas pres-
7. Procedure
sure and electrical continuity from the control unit to the blade.
7.1 Preparation for Testing and Calibration:
6.1.6 Ground Cable, (8) to provide electrical continuity
7.1.1 Select for testing only blades that conform to the
between the push rod system and the calibration unit.
manufacturer’s internal tolerance adjustments and that are in
6.2 Insertion equipment is required to advance the blade to
good visual external condition. The blade should have no
the test depth. The blade may be pushed using the quasi-sta
...