ASTM-D4633-86

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~~ OeslgnaHon: 0 4633 - 86 
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AMERICAN SOCIETY FOR TESTING AND MATERIALS 
1916 Race St.. Philadelphia. Pa. 19103 
Reprinted Irom the Annual Book 01 ASTM Siandards •. Copyrlghl AST~ 
1/ nol listed In Ihe currenl combined Index. Will appear In the next edilion. 
Standard Test Method for 
STRESS WAVE ENERGY MEASUREMENT FOR DYNAMIC 
PENETROMETER TESTING SYSTEMS1 
This standard is issued under the fixed designation 04633; 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 ep5i1on (.) indicates an editorial change since the last revision or reapproval. 
l.Scope 
1.1 This test method describes the procedure 
for measuring that part of the drive weight (ham­
mer) kinetic energy that enters the penetrometer 
connector rod column during dynamic (hammer 
impact) penetrometer testing of soil. 
1.2 This test method has particular applica­
tion to the comparative evaluation of hammer 
systems, and, to a lesser degree of accuracy, ham­
mer-operator systems, that are used for the pen­
etration testing of soils. 
1.3 This test method applies to penetrometers 
driven from above the ground surface. It is not 
intended for use with down-hole hammers. 
1.4 The values stated in inch-pound units are 
to be regarded as the standard. The values in 
parentheses are provided for information only. 
I.S This standard may involve hazardous ma­
terials, operations, and equipment. This standard 
does not purport to address all of the safety prob­
lems associated with its use. It is the responsibil­
ity of the IIser of this standard to establish appro­
priate safety and health practices and determine 
the applicability ofregu{atory limitations prior to 
use. 
2. Terminology 
2.1 Descriptions of Terms Specific to This 
Standard: 
2.1.1 connector rods-the drill rods that con­
nect the drive weight system above the ground 
surface to the penetrometer below the surface. 
2.1.2 engineer-the engineer, geologist, or 
other responsible professional, or their represent­
ative. 
2.1.3 load cell-any instrument placed 
around, on, or Within a continuous column of 
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penetrometer connector rods for the purpose of 
sensing that part of the drive weight (hammer) 
kinetic energy that is transmitted into the pene­
trometer connector rods. 
NOlll I-Some hammer energy is lost at impact 
during the transfer of kinetic energy in the hammer to 
compression wave energy in the penetrometer connec­
tor rods. This impact-transfer loss can vary significantly 
with the shape of the hammer or the anvil, or both. 
with the mass of the anvil. and with the properties of 
any impact cushion at the anvil. 
2.1.4 penetrometer~any sampler, cone. 
blade, or other instrument placed at the bottom 
of the connector rods where the penetration re­
sistance in (hammer blows/penetration distance) 
is used as an index to one or more soil engineer­
ing properties. 
2.1.5 processing instrument-an instrument 
which receives the signal from the load cell after 
a hammer blow and processes it to produce com­
puted E/ or ER/ values (see 2.2.2 and 2.2.3). 
2.1.6 string-cllt drop-supporting a hammer 
on a string at a stipulated distance above the 
anvil and cutting the string to obtain an un­
impeded hammer drop. 
2.2 Symbols: 
2.2.1 E·-the nominal kinetic energy in a 
drive weight of stipulated mass after a gravita­
tional free fall from a stipulated fall height (the 
Newtonian kinetic energy at impact). 
2.2.2 Er-the energy content of the initial 
(first) compression wave that is produced by a 
hammer impact. 
I This test method is under the jurisdiction of ASTM Com­
mittee 0-18 on Soil and Rock and is the direct responsibility of 
Subcommittee D18.02 on Sampling and Related Field Testing 
for Soil Investigations. 
Current edition approved Oct. 31. 1986. Published December 
1986. 
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2.2.3 ERI = (E;/E*) 100 %-measured stress 
wave energy ratio. 
2.2.4 L-length between the hammer impact 
surface and the bottom of the penetrometer. 
2.2.5 L'-length between the load cell and 
the bottom of the penetrometer. 
2.2.6 AL = L - L'. 
3, Significance and Use 
3.1 Various types of driven penetrometers are 
used to evaluate in situ the engineering behavior 
of soils. The penetration resistance of soil to a 
particular driven penetrometer depends not only 
upon the mass of the hammer and the soil char­
acteristics, but upon the continuity and geometry 
of system components and upon system opera­
tion factors that contribute resistance to free-fall 
of the drive weight. Some penetration testing 
systems are only standardized with respect to the 
configuration of the penetrometer and the mass 
of the drive weight. The stress wave integration 
procedure is a method of evaluating variations 
from differences in system geometry and opera­
tion. 
3.2 The incremental penetration of a pene­
trometer from a hammer blow is directly related 
to the magnitude of the irregularly shaped force 
pulse within the first compressive wave from that 
blow. A processing instrument integrates the 
forces within the time limits of the first compres­
sive pulse or wave (idealized example in Fig. I) 
thus computing the stress wave energy of the 
primary force pulse. The integrated stress wave 
energy, therefore, provides an approximate mea­
sure of the effective driving force. 
3.3 The integrated stress wave method has 
particular application to evaluation of hammer 
systems that are used for penetration testing of 
soils. There is an approximate, linear relationship 
between the incremental advance of a driven soil 
penetrometer and the stress wave energy that 
enters the penetrometer connector rods. There­
fore, there is also an approximate inverse rela­
tionship between the penetration resistance (in 
hammer blows per unit length of soil penetration) 
and the stress wave energy, E; (or ERI ). 
3.4 Stress wave measurements may be used to 
evaluate both operator-dependent cathead and 
rope-hammer drop systems and the relatively 
operator-independent mechanized systems. 
When operator-dependent hammer systems are 
tested, the possible inability of the operator to 
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04633 
reproduce environmental influences must be 
considered. 
3.5 This test method has been found useful 
for such purposes as: 
3.5.1 Comparing the dynamic penetration re­
sistances produced by different equipment or 
operators performing the same type of test at a 
project. 
3.5.2 Comparing project penetration resist­
ance with similar design reference data. 
3.5.3 An organization performing internal 
evaluations of their hammer-operator-rig com-
binations. . 
3.5.4 The training of dynamic penetration sys­
tem operators. 
3.5.5 Demonstrating the relative importance· 
of equipment or operator variables. 
3.5.6 Aiding the design of penetrometer drive 
systems. 
3.5.7 Documenting data for regulatory agen­
cies. 
3.5.8 Developing a conversion between differ­
ent types of dynamic penetration tests. 
4. Apparatus 
4.1 Load Cell. Processing Instnlment. and 
Digital Timer-The engineer may use any suit­
able apparatus that measures E; or ERI within 
the required accuracy of ±2 %. Such apparatus 
usually consists of a load cell, processing instru­
ment, and digital timer. 
4.2 Oscilloscope-An oscilIoscope can be a 
useful adjunct, and a digital oscilloscopC hooked 
to a computer can act as a combination instru­
ment and timer. 
5. Procedure 
5.1 Connect the load cell to the penetrometer 
connectorrods no closer than 2.0 It (0.6 m) to 
the base of the anvil. Use load cell adaptors that 
minimize abrupt changes in cross-sectional area 
with respect to the penetrometer connector rods. 
The cross-section of the rods above and below 
the load cell must be the same for a distance of 
at least r.O ft (0.3 m) in both directions. 
5.2 Follow the processing instrument manu­
facturer's calibration procedures to ensure the 
load cell and processing instrument are operating 
properly. Match the processing instrument set­
ting to the type rod used above and below the 
load cell. 
5.2. J If the instrument cannot be preset to the 
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type of rod used, then convert the results from 
that set on or built into the instrument, to that 
actually used by adjusting instrument EI or ER/ 
values by the relative rod cross-sectional areas in· 
accordance with Eqs 1 and 2 (see 5.2.2). All 
connector rods to include the short section be· 
tween the load cell and the anvil must have the 
same section diameter and area. 
5.2.2 Stress Wave Integration Method-The 
stress wave integration method uses the following 
formulae as the basis for making stress wave 
energy comparisons: 
E; = CK:;Kc IAI {F(tW dl (I) 
or 
. _ KIK2KC rOI 
2 
E, - A(Ep)," J, (F(t)l dl (2) 
where: 
F(t) 
E, 
A 
E 
c 
dynamic compressive force in the con­
nector rods as a flInction oftime, 
= energy in the first compression pulse for 
the ideal case of III (and therefore L) = 
infinity, 
time, 
time duration of the first compression 
pulse starting at I = 0, . 
cross-sectional area of the connector 
rods above and below the load cell, 
Young's modulus of the connector rods, 
theoretical velocity of the compression 
wave in the connector rods, .= (Elp)11J 
(see 5.5, 5.6, and Note 5). 
mass density of the connector rods, 
a correction factor to account for the 
compression wave energy not sensed by 
the load cell due to the length, L, of the 
connector rod between the hammer im­
pact surface and the load cell. Table 1 
gives theoretical values of Kl that apply 
with sufficient accuracy over the follow­
ing range of connector rod sizes: parallel 
wall A and A W drill rods to upset wall 
Nand NW drill rods. 
= a theoretical correction factor needed 
when the rod length, L, is less than 45 ft 
(14 m), to correct for the fact that some 
first wave compression energy is cut off 
prematurely when L is less than 45 ft, 
and 
factor to correct the theoretical velocity, 
C, to the actual velocity (see 5.6). 
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04633 
NOTE 2-lf the engineer wishes to adjust E/ or ER/ 
values reported for the infinite L case to the actual Ej 
entering the rods for a case when L :s 4S ft «( 4 m), then 
adjust by dividing the infinite E, value by K2. 
5.3 Do not perform measurements of E/ or 
ERi until several preparatory sequences of blows 
obtained under the same conditions of operator, 
equipment. soil conditions, and the like, have 
been performed by the operator. Record the mea. 
surements by any suitable means. 
NOTE 3-Preparatory sequences of blows have the 
objective of bringing the equipment and operator to 
their normal functioning condition. They can accom­
plish such things as repolishing the cathead. drying wet 
or damp rope, providing fresh lubrication for mechan­
ical parts. identifying any mechanical or human prob­
lems. and providing refamiliarization practice for all 
the personnel concerned with these measurements. 
5.4 Perform a minimum of 30 measurements 
to determine the Ei or ER/ performance of a 
drive weight system. 
NOTE 4-lt is preferable to make as many measure­
ments as practical so as to reduce the statistical sam­
pling error. It is also preferable to make the measure­
ments when using the penetrometer system in as near 
a routine manner as practical. 
5.5 It is necessary to measure c in Eq 1 to 
assure the proper cutoff time for 4(. Ifa process­
ing instrument without an oscilloscope is used. 
then the engineer needs to make as many mea­
surements of the Eq I or 2 integration time 
during each sequence of ham mer blows as needed 
to assure that the instrument makes the proper 
time cutoff (see Note 5). Compare these mea­
surements with the theoretical time to cutoff, as 
follows: 
2L'/c 
where: 
c = the theoretical velocity of a compression 
wave in the rods (approximately 16800 ftf 
s or (5100 m/s) for steel). 
NOTE 5-To conform to the theory in 5;2.2, the 
processing instrument should perform the integration 
until the first time the load cell senses a zero load. This 
should happen when the- compression wave reflects at 
the penetrometer and returns to the load cell as a 
tension wave, at which time the net force at the load 
cell crosses zero force. For some circumstances, partic­
ularly near penetration refusal, the reflected wave arriv­
ing at the load cell may be a compression wave. Under 
these circumstances the force at the load cell may not 
cross zero until significant time after 2L' / c. The instru­
ment will then continue the integration and can give a 
stress wave energy value much greater than that actually 
in the first compression wave. 
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