ASTM D1586 Standard Test Method for Penetration Test and Split-Barrel Sampling of Soils, Thí nghiệm xuyên tiêu chuẩn

ASTM D1586 – 99  Standard Test Method for Penetration Test and Split-Barrel Sampling of Soils

ASTM D1586 – 99  Phương pháp thí nghiệm xuyên tiêu chuẩn SPT hiện trường

  1. Scope

1.1 This test method describes the procedure, generally known as the Standard Penetration Test (SPT), for driving a

split-barrel sampler to obtain a representative soil sample and a measure of the resistance of the soil to penetration of the sampler.

1.2 This standard does not purport to address all of the safety problems, 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. For a specific precautionary statement, see 5.4.1.

1.3 The values stated in inch-pound units are to be regarded as the standard.

ASTM D 1586 – 99  Standard Test Method for Penetration Test and Split-Barrel Sampling of Soils
ASTM D 1586 – 99  Phương pháp thí nghiệm xuyên tiêu chuẩn SPT hiện trường
 

  1. Referenced Documents

2.1 ASTM Standards:

D 2487 Practice for Classification of Soils for Engineering Purposes (Unified Soil Classification System)2

D 2488 Practice for Description and Identification of Soils (Visual-Manual Procedure)2

D 4220 Practices for Preserving and Transporting Soil Samples2

D 4633 Test Method for Stress Wave Energy Measurement for Dynamic Penetrometer Testing Systems2

D 6066 Practice for Determining the Normalized Penetration Resistance Testing of Sands for Evaluation of Liquefaction Potential3

ASTM D 1586  Standard Test Method for Penetration Test and Split-Barrel Sampling of Soils

ASTM D 1586  Phương pháp thí nghiệm xuyên tiêu chuẩn SPT hiện trường

  1. Terminology

3.1 Definitions of Terms Specific to This Standard:

3.1.1 anvil—that portion of the drive-weight assembly which the hammer strikes and through which the hammer

energy passes into the drill rods.

3.1.2 cathead—the rotating drum or windlass in the ropecathead lift system around which the operator wraps a rope to lift and drop the hammer by successively tightening and loosening the rope turns around the drum.

3.1.3 drill rods—rods used to transmit downward force and torque to the drill bit while drilling a borehole.

3.1.4 drive-weight assembly—a device consisting of the hammer, hammer fall guide, the anvil, and any hammer drop system.

3.1.5 hammer—that portion of the drive-weight assembly consisting of the 140 6 2 lb (63.5 6 1 kg) impact weight

which is successively lifted and dropped to provide the energy that accomplishes the sampling and penetration

3.1.6 hammer drop system—that portion of the drive-weight assembly by which the operator accomplishes the lifting and dropping of the hammer to produce the blow.

3.1.7 hammer fall guide—that part of the drive-weight assembly used to guide the fall of the hammer.

3.1.8 N-value—the blowcount representation of the penetration resistance of the soil. The N-value, reported in blows per foot, equals the sum of the number of blows required to drive the sampler over the depth interval of 6 to 18 in. (150 to 450 mm) (see 7.3).

3.1.9 DN—the number of blows obtained from each of the 6-in. (150-mm) intervals of sampler penetration (see 7.3).

3.1.10 number of rope turns—the total contact angle between the rope and the cathead at the beginning of the

operator’s rope slackening to drop the hammer, divided by 360° (see Fig. 1).

3.1.11 sampling rods—rods that connect the drive-weight assembly to the sampler. Drill rods are often used for this

purpose.

3.1.12 SPT—abbreviation for standard penetration test, a term by which engineers commonly refer to this method.

ASTM D1586  Phương pháp thí nghiệm xuyên tiêu chuẩn SPT hiện trường

  1. Significance and Use

4.1 This test method provides a soil sample for identification purposes and for laboratory tests appropriate for soil

obtained from a sampler that may produce large shear strain disturbance in the sample.

4.2 This test method is used extensively in a great variety of geotechnical exploration projects. Many local correlations and

ASTM D 1586  Standard Test Method for Penetration Test and Split-Barrel Sampling of Soils

  1. Apparatus

5.1 Drilling Equipment—Any drilling equipment that provides at the time of sampling a suitably clean open hole before insertion of the sampler and ensures that the penetration test is performed on undisturbed soil shall be acceptable. The following pieces of equipment have proven to be suitable for advancing a borehole in some subsurface conditions.

5.1.1 Drag, Chopping, and Fishtail Bits, less than 6.5 in. (162 mm) and greater than 2.2 in. (56 mm) in diameter may be used in conjuction with open-hole rotary drilling or casingadvancement drilling methods. To avoid disturbance of the underlying soil, bottom discharge bits are not permitted; only side discharge bits are permitted.

5.1.2 Roller-Cone Bits, less than 6.5 in. (162 mm) and greater than 2.2 in. (56 mm) in diameter may be used in

conjunction with open-hole rotary drilling or casingadvancement drilling methods if the drilling fluid discharge is

deflected 5.1.3 Hollow-Stem Continuous Flight Augers, with or without a center bit assembly, may be used to drill the boring. The inside diameter of the hollow-stem augers shall be less than 6.5 in. (162 mm) and greater than 2.2 in. (56 mm).

5.1.4 Solid, Continuous Flight, Bucket and Hand Augers, less than 6.5 in. (162 mm) and greater than 2.2 in. (56 mm) in diameter may be used if the soil on the side of the boring does not cave onto the sampler or sampling rods during sampling.

5.2 Sampling Rods—Flush-joint steel drill rods shall be used to connect the split-barrel sampler to the drive-weight

assembly. The sampling rod shall have a stiffness (moment of inertia) equal to or greater than that of parallel wall “A” rod (a steel rod which has an outside diameter of 15⁄8 in. (41.2 mm) and an inside diameter of 11⁄8 in. (28.5 mm).

5.3 Split-Barrel Sampler—The sampler shall be constructed with the dimensions indicated in Fig. 2. The driving shoe shall be of hardened steel and shall be replaced or repaired when it becomes dented or distorted. The use of liners to produce a constant inside diameter of 13⁄8 in. (35 mm) is permitted, but shall be noted on the penetration record if used. The use of a sample retainer basket is permitted, and should also be noted on the penetration record if used.

5.4 Drive-Weight Assembly:

5.4.1 Hammer and Anvil—The hammer shall weigh 140 6 2 lb (63.5 6 1 kg) and shall be a solid rigid metallic mass. The hammer shall strike the anvil and make steel on steel contact when it is dropped. A hammer fall guide permitting a free fall shall be used. Hammers used with the cathead and rope method shall have an unimpeded overlift capacity of at least 4 in. (100 mm). For safety reasons, the use of a hammer assembly with an

internal anvil is encouraged.

5.4.2 Hammer Drop System—Rope-cathead, trip, semiautomatic, or automatic hammer drop systems may be used,

providing the lifting apparatus will not cause penetration of the sampler while re-engaging and lifting the hammer.

5.5 Accessory Equipment—Accessories such as labels, sample containers, data sheets, and groundwater level measuring devices shall be provided in accordance with the requirements of the project and other ASTM standards.

ASTM D1586  Phương pháp thí nghiệm xuyên tiêu chuẩn SPT hiện trường

  1. Drilling Procedure

6.1 The boring shall be advanced incrementally to permit intermittent or continuous sampling. Test intervals and locations are normally stipulated by the project engineer or geologist. Typically, the intervals selected are 5 ft (1.5 mm) or less in homogeneous strata with test and sampling locations at every change of strata.

6.2 Any drilling procedure that provides a suitably clean and stable hole before insertion of the sampler and assures that the penetration test is performed on essentially undisturbed soil shall be acceptable. Each of the following procedures have proven to be acceptable for some subsurface conditions. The subsurface conditions anticipated should be considered when selecting the drilling method to be used.

6.2.1 Open-hole rotary drilling method.

6.2.2 Continuous flight hollow-stem auger method.

6.2.3 Wash boring method.

6.2.4 Continuous flight solid auger method.

6.3 Several drilling methods produce unacceptable borings. The process of jetting through an open tube sampler and then sampling when the desired depth is reached shall not be permitted. The continuous flight solid auger method shall not be used for advancing the boring below a water table or below the upper confining bed of a confined non-cohesive stratum that is under artesian pressure. Casing may not be advanced below the sampling elevation prior to sampling. Advancing a boring with bottom discharge bits is not permissible. It is not permissible to advance the boring for subsequent insertion of the sampler solely by means of previous sampling with the SPT sampler.

6.4 The drilling fluid level within the boring or hollow-stem augers shall be maintained at or above the in situ groundwater level at all times during drilling, removal of drill rods, and sampling.

ASTM D 1586  Phương pháp thí nghiệm xuyên tiêu chuẩn SPT hiện trường

  1. Sampling and Testing Procedure

7.1 After the boring has been advanced to the desired sampling elevation and excessive cuttings have been removed,

prepare for the test with the following sequence of operations.

7.1.1 Attach the split-barrel sampler to the sampling rods and lower into the borehole. Do not allow the sampler to drop onto the soil to be sampled.

7.1.2 Position the hammer above and attach the anvil to the top of the sampling rods. This may be done before the sampling rods and sampler are lowered into the borehole.

7.1.3 Rest the dead weight of the sampler, rods, anvil, and drive weight on the bottom of the boring and apply a seating blow. If excessive cuttings are encountered at the bottom of the boring, remove the sampler and sampling rods from the boring and remove the cuttings.

7.1.4 Mark the drill rods in three successive 6-in. (0.15-m) increments so that the advance of the sampler under the impact of the hammer can be easily observed for each 6-in. (0.15-m) increment.

7.2 Drive the sampler with blows from the 140-lb (63.5-kg) hammer and count the number of blows applied in each 6-in. (0.15-m) increment until one of the following occurs:

7.2.1 A total of 50 blows have been applied during any one of the three 6-in. (0.15-m) increments described in 7.1.4.

7.2.2 A total of 100 blows have been applied

7.3 Record the number of blows required to effect each 6 in. (0.15 m) of penetration or fraction thereof. The first 6 in. is considered to be a seating drive. The sum of the number of blows required for the second and third 6 in. of penetration is termed the “standard penetration resistance,” or the “N-value.” If the sampler is driven less than 18 in. (0.45 m), as permitted in 7.2.1, 7.2.2, or 7.2.3, the number of blows per each complete 6-in. (0.15-m) increment and per each partial increment shall be recorded on the boring log. For partial increments, the depth of penetration shall be reported to the nearest 1 in. (25 mm),

7.4 The raising and dropping of the 140-lb (63.5-kg) hammer shall be accomplished using either of the following two methods:

7.4.1 By using a trip, automatic, or semi-automatic hammer drop system which lifts the 140-lb (63.5-kg) hammer and allows it to drop 30 6 1.0 in. (0.76 m 6 25 mm) unimpeded.

7.4.2 By using a cathead to pull a rope attached to the Hammer

7.5 Bring the sampler to the surface and open. Record the percent recovery or the length of sample recovered

ASTM D 1586  Phương pháp thí nghiệm xuyên tiêu chuẩn SPT hiện trường

  1. Report

8.1 Drilling information shall be recorded in the field and shall include the following:

8.1.1 Name and location of job,

8.1.2 Names of crew,

8.1.3 Type and make of drilling machine,

8.1.4 Weather conditions,

8.1.5 Date and time of start and finish of boring,

8.1.6 Boring number and location (station and coordinates, if available and applicable),

8.1.7 Surface elevation, if available,

8.1.8 Method of advancing and cleaning the boring,

8.1.9 Method of keeping boring open,

8.1.10 Depth of water surface and drilling depth at the time of a noted loss of drilling fluid, and time and date when reading or notation was made,

8.1.11 Location of strata changes,

8.1.12 Size of casing, depth of cased portion of boring,

8.1.13 Equipment and method of driving sampler,

8.1.14 Type sampler and length and inside diameter of barrel (note use of liners)

8.1.15 Size, type, and section length of the sampling rods, and

8.1.16 Remarks.

8.2 Data obtained for each sample shall be recorded in the field and shall include the following:

8.2.1 Sample depth and, if utilized, the sample number,

8.2.2 Description of soil,

8.2.3 Strata changes within sample,

8.2.4 Sampler penetration and recovery lengths, and

8.2.5 Number of blows per 6-in. (0.15-m) or partial increment.

ASTM D 1586  Standard Test Method for Penetration Test and Split-Barrel Sampling of Soils

  1. Precision and Bias

9.1 Precision—A valid estimate of test precision has not been determined because it is too costly to conduct the

necessary inter-laboratory (field) tests. Subcommittee D18.02 welcomes proposals to allow development of a valid precision statement.

9.2 Bias—Because there is no reference material for this test method, there can be no bias statement.

9.3 Variations in N-values of 100 % or more have been observed when using different standard penetration test apparatus and drillers for adjacent borings in the same soil formation. Current opinion, based on field experience, indicates that when using the same apparatus and driller, N-values in the same soil can be reproduced with a coefficient of variation of about 10 %.

9.4 The use of faulty equipment, such as an extremely massive or damaged anvil, a rusty cathead, a low speed

cathead, an old, oily rope, or massive or poorly lubricated rope sheaves can significantly contribute to differences in N-values obtained between operator-drill rig systems.

9.5 The variability in N-values produced by different drill rigs and operators may be reduced by measuring that part of the hammer energy delivered into the drill rods from the sampler and adjusting N on the basis of comparative energies. A method for energy measurement and N-value adjustment is given in Test Method D 4633

ASTM D1586  Standard Test Method for Penetration Test and Split-Barrel Sampling of Soils

  1. Keywords

blow count; in-situ test; penetration resistance; splitbarrel sampling; standard penetration test

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ASTM D1586-Thi nghiem xuyen tieu chuan SPT

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