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so ghat the advance of the sampler un-
<br />der the impact of the hammer can be
<br />easily observed for each 6-in. (0.15-m)
<br />increment.
<br />
<br /> 7.2 Drive the sampler with blows
<br />from the 140-lb (63.5-kg) hammer and
<br />count the number of blows applied in
<br />each 6-in. (0.15-m) increment until
<br />one of the following occurs:
<br />
<br /> 7.2.1 A total of 50 blows have been
<br />applied during any one of the three
<br />6-in. (O.15-m) increments described in
<br />7.1.4.
<br />
<br /> 7.2.2 A total of 100 blows have been
<br />applied.
<br />
<br /> 7.2.3 There is no observed advance
<br />of the sampler during the application of
<br />10 successive blows of the hammer.
<br />
<br /> 7.2.4 The sampler is advanced the
<br />complete 18 in. (0.45 m) without the
<br />limiting blow counts occurring as de-
<br />scribed in 7.2.1, 7.2.2, or 7.2.3.
<br />
<br /> 7.3 Record the number of blows re-
<br />quired to effect each 6 in. (O.15m) of
<br />penetration or fraction thereof. The
<br />first 6 in. is considered to be a seating
<br />drive. The sum of the number of blows
<br />required for the second and third 6 in.
<br />of penetration is termed the 'standard
<br />penetration resistance", or the
<br />'N-value". If the sampler is driven
<br />less than 18 in. (0.45 m), as permitted
<br />in 7.2.1, 7.2.2, or 7.2.3, the number of
<br />blows per each complete 6-in. (O. 15-m)
<br />increment and per each partial incre-
<br />ment shall be recorded on the boring
<br />log. For partial increments, the depth
<br />of penetration shaft be reported to the
<br />nearest 1 in. (25 mm), in addition to
<br />the number of blows. If the sampler
<br />advances below the bottom of the bor-
<br />Ing under the static weight of the drill
<br />rods or the weight of the drill rods plus
<br />the static weight of the hammer, this
<br />information should be noted on the
<br />boring log.
<br />
<br /> 7.4 The raising and dropping of the
<br />140-lb (63.5-kg) hammer shall be ac-
<br />complished using either of the follow-
<br />hug two methods:
<br />
<br /> 7.4.1 By using a trip, automatic, or
<br />semi-automatic hammer drop system
<br />which lifts the 140-lb (63.5-kg) ham-
<br />mer and allows it to drop 30 ± 1.0 in.
<br />(0.76 m ± 25 mm) unimpeded.
<br />
<br /> 7.4.2 By using a cathead to pull a
<br />rope attached to the hammer. When
<br />the cathead and rope method is used
<br />the system and operation shall con-
<br />form to the following:
<br />
<br /> 7.4.2.1 The cathead shall be essen-
<br />tially free of r~dst, oil, or grease and
<br />have a dt~meter in the range of 6 to 10
<br />in. (150 to 280 mm).
<br />
<br /> ASTM Designation: D 1586
<br />
<br /> 7.4.2.2 The cathead should be
<br />operated at a minimum speed of rota-
<br />tion of 100 BPM, or the approximate
<br />speed of rotation shall be reported on
<br />the boring log.
<br />
<br /> 7.4.2.3 No more than 2~ rope turns
<br />on the cathead may be used during the
<br />performance of the penetration test, as
<br />shown in Fig. 1.
<br />
<br /> NOTE 4--The operator should generally use
<br />either 1 ~ of 2~ rope turns, depending upon
<br />whether or not the rope comes off the top
<br />turns) or the bottom (mZ turns) of the cathead. It
<br />~s generally known and accepted that 2~ or more
<br />rope turns considerably impedes the fall of the
<br />hammer and should not be used to perform the
<br />test. The cathead rope should be mahntained hu a
<br />relatively dry, clean, and unfrayed condition.
<br />
<br /> 7.4.2.4 For each hammer blow, a
<br />30-in. (0.76-m) lift and drop shall be
<br />employed by the operator. The opera-
<br />tion of pulling and throwing the rope
<br />shall be performed rhythmically with-
<br />out holding the rope at the top of th'e~
<br />stroke.
<br />
<br /> 7.5 Bring the sampler to the surface
<br />and open. Record the percent recovery
<br />or length of sample recovered. De-
<br />scribe the soft samples recovered as to
<br />composition, color, stratification, and
<br />condition, then place one or more rep-
<br />resentative portions of the sample into
<br />sealable moisture-proof containers
<br />(jars) without ramming or distorting
<br />any apparent stratification. Seal each
<br />container to prevent evaporation of
<br />soil moisture. Affix labels to the con-
<br />tainers bearing job designation, bor-
<br />ing number, sample depth, and the
<br />blow count per 6-in. (0.15-m~ incre-
<br />ment. Protect the samples against ex-
<br />treme temperature changes: If there is
<br />a soil change within the sampler,
<br />make a Jar for each stratum and note
<br />its location in the sampler barrel.
<br />
<br />8. R~port
<br />
<br /> 8.1 Drilling information shall be
<br />recorded in the field and shall include
<br />the following:
<br />
<br /> 8.1.1 Name and location of job,
<br />
<br /> 8.1.2 Names of crew,
<br />
<br /> 8.1.3 Type and make of drilling
<br />machine,
<br />
<br /> 8.1.4 Weather conditions,
<br />
<br /> 8.1.5 Date and time of start and
<br />finish of boring,
<br />
<br /> 8.1.6 Boring number and location
<br />(station and coordinates, if available
<br />and applicable),
<br />
<br /> 8.1.7 Surface elevation, ff available,
<br />
<br /> 8.1.8 Method of advancing and
<br />cleaning the boring,
<br />
<br /> 8.1.9 Method of keeping boring
<br />open,
<br />
<br /> 8.1.10 Depth of water surface and
<br />drilling depth at the time of a noted
<br />loss of drilling fluid, and time and date
<br />when reading or notation was made,
<br />
<br /> 8.1.11 Location of strata changes,
<br />
<br /> 8.1.12 Size of casing, depth of cased
<br />portion of boring,
<br />
<br /> 8.1.13 Equipment and method of
<br />driving sampler,
<br />
<br /> 8.1.14 Type of sampler and length
<br />and inside diameter of barrel (note use
<br />of liners),
<br />
<br /> 8.1.15 Size, type, and section length
<br />of the sampling rods, and
<br />
<br /> 8..1 .]~6 Remarks.
<br />
<br /> 8.2 Data obtained for each sample
<br />shall~be .recorded in. the field and shall
<br />include the following:
<br />
<br /> 8.2.1 Sample depth and, if utilized,
<br />the sample number,
<br />
<br /> 8.2.2 Description of soft,
<br />
<br /> 8.2.3 Strata changes within sample,
<br />
<br /> 8.2.4 Sampler penetration and re-
<br />covery lengths, and
<br />
<br /> 8.2.5 Number of blows per 6-in.
<br />(0.15-m) or partial increment.
<br />
<br />9. Precision and Bias
<br />
<br /> 9.1 Variations in N-values of 100%
<br />or more have been observed when us-
<br />Lug different standard penetration test
<br />apparatus and drillers for adjacent
<br />borings in the same soil formation.
<br />Cu~ent opinion, based on field experi-
<br />ence; indicates that when using the
<br />same apparatus and driller, N-values
<br />in the same soil can be reproduced
<br />with a coefficient of variation of about
<br />10%.
<br />
<br /> 9.2 The use of faulty equipment,
<br />such as an extremely massive or dam-
<br />aged anvil, a rusty cathead, a low
<br />speed cathead, an old, oily rope, or
<br />massive or poorly lubricated rope
<br />sheaves can significantly contribute to
<br />differences in N-values obtained be-
<br />tween operator-drill rig systems.
<br />
<br /> 9.3 The variability in N-values pro-
<br />duced by different drill rigs and opera-
<br />tors may be reduced by measuring
<br />that part of the hammer energy deliv-
<br />ered into the drill rods from the sam-
<br />pler and adjusting N on the basis of
<br />comparative energies. A method for
<br />energy measurement and N-value ad-
<br />Justment is currently under develop-
<br />ment.
<br />
<br />
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