ASTM D6066-96(2004)
(Practice)Standard Practice for Determining the Normalized Penetration Resistance of Sands for Evaluation of Liquefaction Potential
Standard Practice for Determining the Normalized Penetration Resistance of Sands for Evaluation of Liquefaction Potential
SIGNIFICANCE AND USE
Normalization of penetration resistance data is a frequently used method to evaluate the liquefaction susceptibility of sands. A large case history database from many countries has been accumulated to estimate instability of saturated sands during earthquakes (1,2,3,4). This test is used extensively for a great variety of geotechnical exploration programs where earthquake induced instability of soil needs to be evaluated. Many widely published correlations and local correlations are available, which relate penetration resistance to the engineering properties of soils and the behavior of earthworks and foundations. The data from different countries with differing drilling techniques have been interpreted to develop a preferred normalization approach. This approach has been termed the N1 method proposed by H. Bolton Seed and his colleagues (2,3). Evaluation of liquefaction potential is beyond the scope of this practice. Interpretation of normalized penetration resistance values should be performed by qualified personnel familiar with the multitude of factors influencing interpretation of the data. One purpose of this practice is to attempt to develop a more accurate data base of penetration resistance data from future liquefaction case histories. The normalized penetration resistance determined in this practice may be useful for determination of other engineering properties of sands.
This practice is based on field studies of limited depth and chamber testing of limited stress conditions (1,2,5,6). The existing data bases also are limited in soil types examined. Drilling equipment and methods vary widely from country to country. The majority of data is obtained using the fluid rotary method of drilling with small drill rods and donut or safety type hammers. Some studies have shown that other drilling methods, such as hollow stem augers can be used to successfully collect penetration resistance data (7,8). When using alternate drilling methods, however, it is easier ...
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1.1 This practice outlines a procedure to obtain a record of normalized resistance of sands to the penetration of a standard sampler driven by a standard energy for estimating soil liquefaction potential during earthquakes. The normalized penetration resistance determined in this practice may be useful for determination of other engineering properties of sands.
1.2 This practice uses Test Method D1586 with additions and modifications to minimize disturbance of saturated loose cohesionless sands during drilling. This practice combines results of Test Method D1586 and interprets the data for normalization purposes.
1.3 Due to inherent variability of the SPT, guidance is given on test configuration and energy adjustments. Penetration resistance is adjusted for energy delivered in the penetration test. Energy adjustments can be estimated or measured and reported.
1.4 Standard practice for normalizing penetration resistance values is given. Penetration resistance data are normalized to a standard overburden stress level.
1.5 The normalized penetration resistance data may be used to estimate liquefaction resistance of saturated sands from earthquake shaking. Evaluation of liquefaction resistance may be applied to natural ground conditions or foundations for either planned or existing structures.
1.6 Using this practice representative disturbed samples of the soil can be collected for identification purposes.
1.7 This practice is limited to use in cohesionless soils (see Test Method D2487 and classifications of SM, SW, SP, SP-SM, and SW-SM Practice D2488). In most cases, testing is performed in saturated deposits below the water table. In some cases, dry sands may be tested (see 5.4). This practice is not applicable to lithified materials or fine grained soils. Gravel can interfere with the test and result in elevated penetration resistance values. Normalization of penetration resistance values for gravelly soils is...
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Designation:D6066–96 (Reapproved 2004)
Standard Practice for
Determining the Normalized Penetration Resistance of
Sands for Evaluation of Liquefaction Potential
This standard is issued under the fixed designation D6066; 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 (´) indicates an editorial change since the last revision or reapproval.
1. Scope 1.8 Penetration resistance measurements often will involve
safety planning, administration, and documentation. This prac-
1.1 This practice outlines a procedure to obtain a record of
tice does not purport to address all aspects of exploration and
normalized resistance of sands to the penetration of a standard
site safety. This standard does not purport to address all of the
sampler driven by a standard energy for estimating soil
safety concerns, if any, associated with its use. It is the
liquefaction potential during earthquakes. The normalized
responsibility of the user of this standard to establish appro-
penetrationresistancedeterminedinthispracticemaybeuseful
priate safety and health practices and determine the applica-
for determination of other engineering properties of sands.
bility of regulatory limitations prior to use. Performance of the
1.2 This practice uses Test Method D1586 with additions
test usually involves use of a drill rig; therefore, safety
and modifications to minimize disturbance of saturated loose
requirements as outlined in applicable safety standards. For
cohesionless sands during drilling. This practice combines
2 3
example, OSHA regulations, DCDMA safety manual, drill-
results of Test Method D1586 and interprets the data for
ing safety manuals, and other applicable state and local
normalization purposes.
regulations must be observed.
1.3 Due to inherent variability of the SPT, guidance is given
1.9 The values stated in inch-pound units are to be regarded
on test configuration and energy adjustments. Penetration
as standard. Within the text, the SI units, are shown in
resistance is adjusted for energy delivered in the penetration
parentheses. The values stated in each system are not equiva-
test. Energy adjustments can be estimated or measured and
lents,therefore,eachsystemmustbeusedindependentlyofthe
reported.
other.
1.4 Standard practice for normalizing penetration resistance
1.9.1 In pressure correction calculations, common units are
values is given. Penetration resistance data are normalized to a
2 2
ton/ft , kg/cm , atm, and bars. Since these units are approxi-
standard overburden stress level.
matelyequal(withinafactorof1.1),manyengineerspreferthe
1.5 The normalized penetration resistance data may be used
use of these units in stress correction calculations. For those
to estimate liquefaction resistance of saturated sands from
using kPa or kN/m , 100 kPa is approximately equal to one
earthquake shaking. Evaluation of liquefaction resistance may
ton/ft . The stress exponent, n, (see 3.3.1) is approximately
be applied to natural ground conditions or foundations for
equal for these units.
either planned or existing structures.
1.10 This practice may not be applicable in some countries,
1.6 Using this practice representative disturbed samples of
states, or localities, where rules or standards may differ for
the soil can be collected for identification purposes.
applying penetration resistance to liquefaction estimates. Other
1.7 This practice is limited to use in cohesionless soils (see
practices exist for estimating soil instability from penetration
TestMethodD2487andclassificationsofSM,SW,SP,SP-SM,
resistance data. Procedures may change with advances in
and SW-SM Practice D2488). In most cases, testing is per-
geotechnical engineering. It is dependent on the user in
formed in saturated deposits below the water table. In some
consultation with experienced engineers to select appropriate
cases, dry sands may be tested (see 5.4). This practice is not
methods and correction to data. In earthquake engineering
applicabletolithifiedmaterialsorfinegrainedsoils.Gravelcan
studies, many phenomena can affect soil instability. The
interfere with the test and result in elevated penetration
practice reflects only one current exploration technique and
resistance values. Normalization of penetration resistance val-
method for normalizing penetration resistance data to a com-
ues for gravelly soils is beyond the scope of this practice.
mon level for comparisons to case history information.
1.11 This practice offers a set of instructions for performing
one or more specific operations. This document cannot replace
This practice is under the jurisdiction of ASTM Committee D18 on Soil and
Rock and is the direct responsibility of Subcommittee D18.02 on Sampling and
Related Field Testing for Soil Evaluations.
Current edition approved Nov. 1, 2004. Published January 2005. Originally Available from OSHA, 1825 K. Street, NW, Washington, DC 20006.
e1 3
approved in 1996. Last previous edition approved in 1996 as D6066–96 . DOI: Available from the Drilling Equipment Manufacturers Association, 3008
10.1520/D6066-96R04. Millwood Avenue, Columbia, SC 29205.
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.
D6066–96 (2004)
education or experience and should be used in conjunction 3.2.2 automatic hammer, n—a hammer drop system that
withprofessionaljudgment.Notallaspectsofthispracticemay uses mechanical means to lift and control drop height of the
be applicable in all circumstances. This ASTM standard is not hammer.
intended to represent or replace the standard of care by which
3.2.3 cathead, n—a spinning sheave or rotating drum
the adequacy of a given professional service must be judged,
around which the operator wraps the rope used to lift and drop
nor should this document be applied without consideration of
the hammer by successively tightening and loosening the rope
a project’s many unique aspects. The word “Standard” in the
turns around the drum.
title of this document means only that the document has been
3.2.4 cleanout depth, n—depth that the bottom of the
approved through the ASTM consensus process.
cleanout tool (end of drill bit or cutter teeth) reaches before
termination of cleanout procedures.
2. Referenced Documents
3.2.5 cleanout interval, n—interval between successive
2.1 ASTM Standards:
penetration resistance tests from which material must be
D653 Terminology Relating to Soil, Rock, and Contained removed using conventional drilling methods. During the
Fluids
clean-out process, the previous penetration test interval (1.5 ft,
D1586 Test Method for Penetration Test (SPT) and Split- 45 cm) is drilled through and additional distance is cleaned to
Barrel Sampling of Soils assure minimal disturbance of the next test interval. The term
D2216 Test Methods for Laboratory Determination of Wa- clean out interval in this practice refers to the additional
ter (Moisture) Content of Soil and Rock by Mass distance past the previous test.
D2487 Practice for Classification of Soils for Engineering
3.2.6 crown block—apulley,setofpulleys,orsheavesatthe
Purposes (Unified Soil Classification System)
top of the drill derrick or mast on or over which the hoist or
D2488 Practice for Description and Identification of Soils
other lines, or both, run.
(Visual-Manual Procedure)
3.2.7 cylinder hammer, n—drive weight assembly consist-
D3740 Practice for Minimum Requirements for Agencies
ing of a guide pipe, anvil, jar coupling, and an open cylindrical
Engaged in Testing and/or Inspection of Soil and Rock as
hammer. Also called a donut or casing hammer.
Used in Engineering Design and Construction
3.2.8 downhole hammer, n—a hammer lowered down the
D4633 Test Method for Energy Measurement for Dynamic
drill hole and attached a short distance above the sampler.
Penetrometers
3.2.9 donut hammer, n—see cylinder hammer.
D5434 Guide for Field Logging of Subsurface Explorations
3.2.10 drill rods, n—rods used to transmit downward and
of Soil and Rock
rotary force to the sampler or drill bit.
D5778 TestMethodforElectronicFrictionConeandPiezo-
3.2.11 drill rod energy ratio, ER(see Test Method D4633),
i
cone Penetration Testing of Soils
n—measured stress wave energy ratio. The ratio is that of
energymeasuredindrillrodscontainedinthefirstcompression
3. Terminology
wave to nominal energy of the drive weight system.
3.1 Definitions: Definitions of terms included in Terminol-
3.2.12 drive interval, n—interval from 0.0 to 1.5 ft (45 cm)
ogy D653 specific to this practice are:
below the cleanout depth that consists of the 0.5 ft (15 cm)
3.1.1 effective stress—the average normal force per unit
seating and the 1.0 ft (30 cm) test interval.
area transmitted from grain to grain of a soil mass (see 13.4.1).
3.2.13 drive length, n—total length of the drive interval
3.1.2 equilibrium pore water pressure, u —at rest water
o
penetrated during testing, that is, the measured distance the
pressure at depth of interest. Same as hydrostaic pressure (see
sampler is actually advanced.
13.4.1.1).
3.2.14 drive weight assembly, n—an assembly that consists
3.1.3 liquefaction—the process of transforming any soil
of the hammer, anvil, hammer fall guide system, drill rod
from a solid state to a liquid state, usually as a result of
attachment system, and any hammer drop system hoisting
increased pore pressure and reduced shearing resistance.
attachments.
3.1.4 standard penetration resistance, N—the number of
3.2.15 hammer, n—that portion of the drive weight assem-
blows of a 140 lbm (63.5 kg) hammer falling 30 in. (76 cm)
bly consisting of the 140-lbm impact mass that is lifted
required to produce1fof penetration of a specified (standard)
successively and dropped to provide the energy that accom-
2-in. outside diameter, 1 ⁄8-in. inside diameter sampler into
plishes the penetration and sampling.
soil, after an initial 0.5 f seating.
3.2.16 hammer drop system, n—that portion of the drive
3.2 Definitions of Terms Specific to This Standard:
weight assembly by which the operator accomplishes the
3.2.1 anvil, n—that portion of the drive assembly that the
lifting and dropping of the hammer to produce the blow.
hammer strikes and through which the hammer energy is
3.2.17 number of rope turns, n—the number of times a rope
transmitted into the drill rods.
is wrapped completely around the cathead. Penetration resis-
tance testing is performed using two nominal rope turns on the
cathead. Depending on operator position, direction of cathead
For referenced ASTM standards, visit the ASTM website, www.astm.org, or
rotation,andtheangleatwhichtheropeleavesthecathead,the
contact ASTM Customer Service at service@astm.org. For Annual Book of ASTM
3 1
actual number of turns typically varies from 1 ⁄4 to 2 ⁄4 turns
Standards volume information, refer to the standard’s Document Summary page on
the ASTM website. (Fig. 1).
D6066–96 (2004)
3.2.23 vertical effective stress, n, s8 —the average effective
v
force per unit area transmitted from grain to grain of a soil
mass normal to the horizontal plane (see 13.4.1 for calcula-
tion).
3.3 Abbreviations:Symbols and Abbreviations:
3.3.1 n—stress exponent in the equation:
n
C 5 ~s8 /s8 ! (1)
N vref v
where:
s8 = reference stress level,
vref
s8 = vertical effective stress at test depth,
v
s8 = 1 tsf ('1kg /cm , ' 1 bar, ' 1 atm), and
vref f
n
C = 1/(s8 ) .
n v
3.3.2 N value—the sum of the hammer blows required to
drive the sampler over the test interval from 0.5 to 1.5 ft (15 to
45 cm) below the cleanout depth.
3.3.3 N —penetration resistance adjusted to a 60 % drill
rod energy ratio (see 13.3.2).
3.3.4 (N ) —penetration resistance adjusted for energy and
1 60
stress level.
3.3.5 SPT—abbreviation for standard penetration test of
penetration resistance testing.
FIG. 1 Number of Rope Turns on Cathead
3.2.18 rope, cathead method, n—a method of raising and 4. Summary of Practice
dropping the hammer, which uses a rope strung through a
4.1 Drilling is performed with minimal disturbance to ad-
center crown sheave or pulley on the drill mast and turns on a
vance a boring to the test interval. For loose sand, specific
cathead to lift the hammer.
measures and quality checks may be required to assure
3.2.19 safety hammer, n—drive weight assembly consisting
minimal disturbance. If disturbance is evident, an alternate
of a center guide rod, internal anvil, and hammer that encloses
drilling method may be required.
the hammer-anvil contact (Fig. 2).
4.2 Afteraninitialseatingdriveof0.5ft(15cm),astandard
3.2.20 seating interval, n—interval from 0.0 to 0.5-ft (0 to
penetration resistance sampler is driven 1.0 ft (30 cm) into soil
15 cm) below the cleanout depth.
below the bottom of a drill hole using a 140-lbm hammer,
3.2.21 test interval, n—interval from 0.5 to 1.5 ft (15 to 45
dropped 30 in. (75 cm). Penetration resistance, N, is expressed
cm) below the cleanout depth.
as the number of hammer blows required to drive the sampler
3.2.22 trip hammers, n—hammers hoisted by rope-cathead
the 1.0-ft (30-cm) distance.
method and mechanically released for a drop without rope
attached. 4.3 In Method A, the penetration resistance is adjusted to a
drill rod energy ratio of 60 %, N , by using hammer systems
with an estimated energy delivery. Safety hammers with
rope-cathead operation are assumed to deliver approximately
60 % drill rod energy (Er ' 60 %).Automatic hammer energy
i
must be documented in previous measurements for a particular
make and model, either by the manufacturer or from previous
measurements by other entities.
4.4 In Method B, penetration resistance data is adjusted to
60 % drill rod energy ratio through directly measured drill rod
stress wave energy using Test Method D4633 or other docu-
mentedprocedures.Theadjustmentcanbemadetothe Nvalue
for a particular hammer system or the hammer system may be
adjusted to deliver 60 % drill rod energy (see 6.4.2).
4.5 The N value is normalized to an effective overburden
pressure of 1-tsf ('1 kg/cm , bar, atm) using overburden
pressure correction factors from chamber tests. Typical adjust-
ment factors are given to the user (see 13.4). The user may
adjust the factors depending on the nature of the foundation
FIG. 2 Internal Anvil Safety Hammers—Typical Designs soils, such as, previous stress history, particle size.
D6066–96 (2004)
5. Significance and Use ratio, ER,TestMethodD4633andofthepenetrationresistance
i
test, Test Method D1586. The current practice consists of
5.1 Normalization of penetration re
...
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