ASTM D5778-95(2000)
(Test Method)Standard Test Method for Performing Electronic Friction Cone and Piezocone Penetration Testing of Soils
Standard Test Method for Performing Electronic Friction Cone and Piezocone Penetration Testing of Soils
SIGNIFICANCE AND USE
Tests performed using this test method provide a detailed record of cone resistance which is useful for evaluation of site stratigraphy, homogeneity and depth to firm layers, voids or cavities, and other discontinuities. The use of a friction sleeve and pore pressure element can provide an estimate of soil classification, and correlations with engineering properties of soils. When properly performed at suitable sites, the test provides a rapid means for determining subsurface conditions.
This test method provides data used for estimating engineering properties of soil intended to help with the design and construction of earthworks, the foundations for structures, and the behavior of soils under static and dynamic loads.
This test method tests the soil in situ and soil samples are not obtained. The interpretation of the results from this test method provides estimates of the types of soil penetrated. Engineers may obtain soil samples from parallel borings for correlation purposes but prior information or experience may preclude the need for borings.
SCOPE
1.1 This test method covers the procedure for determining the resistance to penetration of a conical pointed penetrometer as it is advanced into subsurface soils at a slow, steady rate.
1.2 This test method is also used to determine the frictional resistance of a cylindrical sleeve located behind the conical point as it is advanced through subsurface soils at a slow, steady rate.
1.3 This test method applies to friction-cone penetrometers of the electronic type.
1.4 This test method can be used to determine pore pressure development during push of a piezocone penetrometer. Pore pressure dissipation, after a push, can also be monitored for correlation to soil compressibility and permeability.
1.5 Other sensors such as inclinometer, seismic, and temperature sensors may be included in the penetrometer to provide useful information. The use of an inclinometer is highly recommended since it will provide information on potentially damaging situations during the sounding process.
1.6 Cone penetration test data can be used to interpret subsurface stratigraphy, and through use of site specific correlations it can provide data on engineering properties of soils intended for use in design and construction of earthworks and foundations for structures.
1.7 The values stated in SI units are to be regarded as standard. Within Section 13 on Calculations, SI metric units are considered the standard. Other commonly used units such as the inch-pound system are shown in brackets. The various data reported should be displayed in mutually compatible units as agreed to by the client or user. Cone tip projected area is commonly referred to in centimetres for convenience. The values stated in each system are not equivalents; therefore, each system must be used independently of the other.
Note 1--This test method does not include hydraulic or pneumatic penetrometers. However, many of the procedural requirements herein could apply to those penetrometers.
1.8 This standard does not purport to address all of the safety concerns, if any, 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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Designation: D 5778 – 95 (Reapproved 2000)
Standard Test Method for
Performing Electronic Friction Cone and Piezocone
Penetration Testing of Soils
This standard is issued under the fixed designation D5778; 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.
1. Scope 1.8 This standard does not purport to address all of the
safety concerns, if any, associated with its use. It is the
1.1 This test method covers the procedure for determining
responsibility of the user of this standard to establish appro-
the resistance to penetration of a conical pointed penetrometer
priate safety and health practices and determine the applica-
as it is advanced into subsurface soils at a slow, steady rate.
bility of regulatory limitations prior to use.
1.2 This test method is also used to determine the frictional
resistance of a cylindrical sleeve located behind the conical
2. Referenced Documents
point as it is advanced through subsurface soils at a slow,
2.1 ASTM Standards:
steady rate.
D653 Terminology Relating to Soil, Rock, and Contained
1.3 This test method applies to friction-cone penetrometers
Fluids
of the electronic type.
E4 Practice for Force Verification of Testing Machines
1.4 Thistestmethodcanbeusedtodetermineporepressure
development during push of a piezocone penetrometer. Pore
3. Terminology
pressure dissipation, after a push, can also be monitored for
3.1 Definitions:
correlation to soil compressibility and permeability.
3.1.1 Definitions are in accordance with Terminology
1.5 Other sensors such as inclinometer, seismic, and tem-
D653.
perature sensors may be included in the penetrometer to
3.2 Definitions of Terms Specific to This Standard:
provide useful information. The use of an inclinometer is
3.2.1 apparent load transfer—apparentresistancemeasured
highly recommended since it will provide information on
on either the cone or friction sleeve of an electronic cone
potentially damaging situations during the sounding process.
penetrometer while that element is in a no-load condition but
1.6 Cone penetration test data can be used to interpret
the other element is loaded. Apparent load transfer is the sum
subsurface stratigraphy, and through use of site specific corre-
of cross talk, subtraction error, and mechanical load transfer.
lations it can provide data on engineering properties of soils
3.2.2 baseline—a set of zero load readings, expressed in
intended for use in design and construction of earthworks and
terms of apparent resistance, that are used as reference values
foundations for structures.
during performance of testing and calibration.
1.7 The values stated in SI units are to be regarded as
3.2.3 cone—the conical point of a cone penetrometer on
standard.WithinSection13onCalculations,SImetricunitsare
which the end bearing component of penetration resistance is
considered the standard. Other commonly used units such as
developed. The cone has a 60° apex angle, a projected
theinch-poundsystemareshowninbrackets.Thevariousdata
(horizontal plane) surface area or cone base area of 10 or 15
reported should be displayed in mutually compatible units as
cm , and a cylindrical extension behind the cone base.
agreed to by the client or user. Cone tip projected area is
3.2.4 cone penetration test—aseriesofpenetrationreadings
commonly referred to in centimetres for convenience. The
performed at one location over the entire depth when using a
values stated in each system are not equivalents; therefore,
cone penetrometer. Also referred to as cone sounding.
each system must be used independently of the other.
3.2.5 cone penetrometer—apenetrometerinwhichthelead-
NOTE 1—This test method does not include hydraulic or pneumatic
ing end of the penetrometer tip is a conical point designed for
penetrometers. However, many of the procedural requirements herein
penetrating soil and for measuring the end-bearing component
could apply to those penetrometers.
of penetration resistance.
3.2.6 cone resistance, q —the end-bearing component of
c
penetration resistance.The resistance to penetration developed
ThistestmethodisunderthejurisdictionofASTMCommitteeD18onSoiland
Rock and is the direct responsibility of Subcommittee D18.02 on Sampling and
Related Field Testing for Soil Evaluations. Annual Book of ASTM Standards, Vol 04.08.
Current edition approved Sept. 10, 1995. Published January 1996. Annual Book of ASTM Standards, Vol 03.01.
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.
D 5778
on the cone is equal to the vertical force applied to the cone 3.2.22 penetrometer—an apparatus consisting of a series of
divided by the cone base area. cylindricalpushrodswithaterminalbody(endsection),called
the penetrometer tip, and measuring devices for determination
3.2.7 corrected total cone resistance, q—tip resistance
t
of the components of penetration resistance.
corrected for water pressure acting behind the tip (see 13.2.1).
3.2.23 penetrometer tip—the terminal body (end section) of
Correction for water pressure requires measuring water pres-
the penetrometer which contains the active elements that sense
sures with a piezocone element behind the tip at location u .
thecomponentsofpenetrationresistance.Thepenetrometertip
The correction results in estimated total tip resistance.
may include additional electronic instrumentation for signal
3.2.8 crosstalk—anapparentloadtransferbetweenthecone
conditioning and amplification.
and the friction sleeve caused by interference between the
3.2.24 piezocone—same as electronic piezocone penetrom-
separate signal channels.
eter (see 3.2.10).
3.2.9 electronic cone penetrometer—a friction cone pen-
3.2.25 piezocone pore pressure, u—fluid pressure measured
etrometer that uses force transducers, such as strain gage load
using the piezocone penetration test.
cells, built into a non-telescoping penetrometer tip for measur-
3.2.26 piezocone pore pressure measurement locations, u ,
ing,withinthepenetrometertip,thecomponentsofpenetration
u ,u —fluidpressuremeasuredbythepiezoconepenetrometer
resistance. 2
at specific locations on the penetrometer as follows: u —pore
3.2.10 electronic piezocone penetrometer—an electronic
pressure filter location on the face or tip of the cone, u —pore
cone penetrometer equipped with a low volume fluid chamber,
pressure filter location immediately behind the cone tip (stan-
porous element, and pressure transducer for determination of
dard location) and, u —pore pressure filter location behind the
pore pressure at the porous element soil interface.
friction sleeve.
3.2.11 end bearing resistance—same as cone resistance or
3.2.27 pore pressure ratio—the ratio of excess pore pres-
tip resistance, q .
c
sure, Du, to cone resistance, q , expressed as a percentage (see
c
3.2.12 equilibrium pore water pressure, u —at rest water
13.5.3).
pressure at depth of interest. Same as hydrostatic pressure (see
3.2.28 pore pressure ratio parameter, B —the ratio of
q
Terminology D653).
excessporepressureatmeasurementlocation Du ,tocorrected
3.2.13 excess pore water pressure, Du—the difference be-
total cone resistance q, minus the total vertical stress, s (see
t v
tweenporepressuremeasuredasthepenetrationoccurs, u,and
13.5.4.1).
estimated equilibrium pore water pressure (u − u). Excess
3.2.29 push rods—the thick-walled tubes or rods used to
pore pressure can either be positive or negative.
advance the penetrometer tip.
3.2.14 friction cone penetrometer—a cone penetrometer 3.2.30 sleeve friction, sleeve, and friction resistance—same
with the capability of measuring the friction component of
as friction sleeve resistance.
penetration resistance. 3.2.31 subtraction error—an apparent load transfer from
the cone to the friction sleeve of a subtraction type electronic
3.2.15 friction ratio, R—the ratio of friction sleeve resis-
f
cone penetrometer caused by minor voltage differences in
tance, f , to cone resistance, q , measured at where the middle
s c
response to load between the two strain element cells.
of the friction sleeve and cone point are at the same depth,
3.3 Abbreviations:
expressed as a percentage.
3.3.1 CPT—abbreviation for the cone penetration test.
3.2.16 friction reducer—a narrow local protuberance on the
3.3.2 CPTu—abbreviation for the piezocone penetration
outside of the push rod surface, placed at a certain distance
test.
above the penetrometer tip, that is provided to reduce the total
side friction on the push rods and allow for greater penetration
4. Summary of Test Method
depths for a given push capacity.
4.1 A penetrometer tip with a conical point having a 60°
3.2.17 friction sleeve—anisolatedcylindricalsleevesection
apex angle and a cone base area of 10 or 15 cm is advanced
on a penetrometer tip upon which the friction component of
throughthesoilataconstantrateof20mm/s.Theforceonthe
penetration resistance develops. The friction sleeve has a
conical point (cone) required to penetrate the soil is measured
surface area of either 150 for 10 cm cone tip.
by electrical methods, at a minimum of every 50 mm of
3.2.18 friction sleeve resistance, f —thefrictioncomponent
s
penetration.Stressiscalculatedbydividingthemeasuredforce
of penetration resistance developed on a friction sleeve, equal
(total cone force) by the cone base area to obtain cone
to the shear force applied to the friction sleeve divided by its
resistance, q .
c
surface area.
4.2 A friction sleeve is present on the penetrometer imme-
3.2.19 FSO—abbreviation for full-scale output. The output
diatelybehindtheconetip,andtheforceexertedonthefriction
of an electronic force transducer when loaded to 100% rated
sleeve is measured by electrical methods at a minimum of
capacity.
every 50 mm of penetration. Stress is calculated by dividing
3.2.20 local side friction—same as friction sleeve resis-
the measured force by the surface area of the friction sleeve to
tance.
determine friction sleeve resistance, f .
s
3.2.21 penetration resistance measuring system— a mea- 4.3 Many penetrometers are capable of registering pore
suring system that provides the means for transmitting infor- water pressure induced during advancement of the penetrom-
mationfromthepenetrometertipanddisplayingthedataatthe eter tip using an electronic pressure transducer. These pen-
surface where it can be seen or recorded. etrometersarecalled“piezocones.”Thepiezoconeisadvanced
D 5778
at a rate of 20 mm/s, and readings are taken at a minimum of
every 50 mm of penetration. The dissipation of either positive
or negative excess pore water pressure can be monitored by
stopping penetration, unloading the push rod, and recording
pore pressure as a function of time. When pore pressure
becomes constant it is measuring the equilibrium value or
piezometric level at that depth.
5. Significance and Use
5.1 Tests performed using this test method provide a de-
tailed record of cone resistance which is useful for evaluation
of site stratigraphy, homogeneity and depth to firm layers,
voidsorcavities,andotherdiscontinuities.Theuseofafriction
sleeve and pore pressure element can provide an estimate of
soil classification, and correlations with engineering properties
of soils. When properly performed at suitable sites, the test
provides a rapid means for determining subsurface conditions.
5.2 This test method provides data used for estimating
engineering properties of soil intended to help with the design
and construction of earthworks, the foundations for structures,
FIG. 1 Typical Electric Friction—Cone Penetrometer Tip
and the behavior of soils under static and dynamic loads. Configurations (1)
5.3 This test method tests the soil in situ and soil samples
are not obtained.The interpretation of the results from this test
cells. The load cells are joined together in such a manner that
method provides estimates of the types of soil penetrated.
the cell nearest the cone (the “C” cell on Fig. 1(b)) measures
Engineers may obtain soil samples from parallel borings for
the compressive force on the cone while the second cell (the
correlation purposes but prior information or experience may
“C+S” cell on Fig. 1( b)) measures the sum of the compres-
preclude the need for borings.
sive forces on both the cone and friction sleeve. The compres-
6. Interferences
sive force from just the friction sleeve is computed then by
subtraction. This cone design finds the most common use in
6.1 Refusal, deflection, or damage to the penetrometer may
industry. It is preferred because of its rugged design. This
occur in coarse grained soil deposits with maximum particle
designformsthebasisforminimumperformancerequirements
sizes that approach or exceed the diameter of the cone.
for electronic penetrometers.
6.2 Partially lithified and lithified deposits may cause re-
7.1.1.1 In the independent tension-type cone penetrometer
fusal, deflection, or damage to the penetrometer.
tip, the cone produces a compression force on the cone load
6.3 Standard push rods can be damaged or broken under
cell (the “C” cell on Fig. 1(a)) while the friction sleeve
extreme loadings. The amount of force that push rods are able
producesatensileforceontheindependentfrictionsleeveload
to sustain is a function of the unrestrained length of the rods
cell (the “S” cell on Fig. 1(a)). Designs are also available
andtheweaklinksinthepushrod-penetrometertipstringsuch
where the independent sleeve element is placed in compres-
as push rod joints and push rod-penetrometer tip connections.
sion.This penetrometer tip design results in a higher degree of
The force at which rods may break is a function of the
accuracyinfrictionsleevemeasurement,but,dependingonthe
equipment configuration and ground conditions during pen-
design,itismoresusceptibletodamageunderextremeloading
etration. Excessive rod deflection is the most common cause
conditions.
for rod breakage.
7.1.1.2 Typical general purpose cone penetrometers are
7. Apparatus manufacturedtofullscaleoutputsequivalenttonetloadsof10
to 20 tons. Often, weak soils are the most critical in an
7.1 Friction Cone Penetrometer—The penetrometer tip
investigation program and in some cases very accurate friction
should meet requirements as given below and in 10.1. In a
sleevedatamayberequired.Togainbetterresolution,theFSO
typicalfrictionconepenetrometertip(asshownonFig.1(1)),
can be lowered or independent type penetrometers can be
the forces produced by friction sleeve resistance and cone
selected. A low FSO subtraction co
...
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