1、Designation: D 7380 08Standard Test Method forSoil Compaction Determination at Shallow Depths Using5-lb (2.3 kg) Dynamic Cone Penetrometer1This standard is issued under the fixed designation D 7380; the number immediately following the designation indicates the year oforiginal adoption or, in the ca
2、se of revision, the year of last revision. A number in parentheses indicates the year of last reapproval. Asuperscript epsilon (e) indicates an editorial change since the last revision or reapproval.1. Scope1.1 This test method covers the procedure for the determi-nation of the number of drops requi
3、red for a dynamic conepenetrometer with a 5-lb (2.3-kg) drop hammer falling 20 in.(508 mm) to penetrate a certain depth in compacted backfill.1.2 The device is used in the compaction verification offine- and coarse-grained soils, granular materials, and weakstabilized or modified material used in su
4、bgrade, base layers,and backfill compaction in confined cuts and trenches atshallow depth.1.3 The test method is not applicable to highly stabilizedand cemented materials or granular materials containing a largepercentage of aggregates greater than 1.5 in. (37 mm).1.4 The method is dependent upon kn
5、owing the field watercontent and the user having performed calibration tests todetermine cone penetration resistance of various compactionlevels and water contents.1.5 The values stated in inch-pound units are to be regardedas standard. The values given in parentheses are mathematicalconversions to
6、SI units that are provided for information onlyand are not considered standard.NOTE 1It is common practice in the engineering profession toconcurrently use pounds to represent both a unit of mass (lbm) and a force(lbf).This standard has been written using the gravitational system of units(lbf) when
7、dealing with the inch-pound system. In this system, the pound(lbf) represents a unit of force (weight). However, the use of balances orscales recording pounds of mass (lbm) or the reading of density in lbm/ft3shall not be regarded as a nonconformance with this standard.1.6 All observed and calculate
8、d values shall conform to theguidelines for significant digits and rounding established inPractice D 6026.1.7 This standard does not purport to address all of thesafety concerns, if any, associated with its use. It is theresponsibility of the user of this standard to establish appro-priate safety an
9、d health practices and determine the applica-bility of regulatory limitations prior to use.2. Referenced Documents2.1 ASTM Standards:2D 653 Terminology Relating to Soil, Rock, and ContainedFluidsD 698 Test Methods for Laboratory Compaction Character-istics of Soil Using Standard Effort (12 400 ft-lb
10、f/ft3(600kN-m/m3)D 1556 Test Method for Density and Unit Weight of Soil inPlace by Sand-Cone MethodD 1557 Test Methods for Laboratory Compaction Charac-teristics of Soil Using Modified Effort (56,000 ft-lbf/ft3(2,700 kN-m/m3)D 2216 Test Methods for Laboratory Determination of Wa-ter (Moisture) Conte
11、nt of Soil and Rock by MassD 3740 Practice for Minimum Requirements for AgenciesEngaged in Testing and/or Inspection of Soil and Rock asUsed in Engineering Design and ConstructionD 4959 Test Method for Determination of Water (Moisture)Content of Soil By Direct HeatingD 6026 Practice for Using Signif
12、icant Digits in Geotechni-cal DataD 6938 Test Method for In-Place Density and Water Con-tent of Soil and Soil-Aggregate by Nuclear Methods(Shallow Depth)D 6951 Test Method for Use of the Dynamic Cone Pen-etrometer in Shallow Pavement ApplicationsE 691 Practice for Conducting an Interlaboratory Study
13、 toDetermine the Precision of a Test Method3. Terminology3.1 Definitions: Refer to Terminology D 653 for standarddefinition of terms.3.2 Definitions of Terms Specific to This Standard:3.2.1 5-lb dynamic cone penetrometer (5-lb DCP)(Fig. 1)a device that uses a 5-lb (2.3-kg) hammer to penetrate a cone
14、tip inside the soil where the number of drops needed to1This test method is under the jurisdiction ofASTM Committee D18 on Soil andRock and is the direct responsibility of Subcommittee D18.08 on Special andConstruction Control Tests.Current edition approved April 1, 2008. Published April 2008.2For r
15、eferenced ASTM standards, visit the ASTM website, www.astm.org, orcontact ASTM Customer Service at serviceastm.org. For Annual Book of ASTMStandards volume information, refer to the standards Document Summary page onthe ASTM website.1Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700,
16、West Conshohocken, PA 19428-2959, United States.penetrate a certain distance between two marks on the drivingrod is used to determine soil compaction effort.3.2.2 extension rodin dynamic cone penetrometer, anoptional extension of the driving rod to allow the use of the5-lb DCP in deep confined holes
17、.3.2.2.1 DiscussionThe extension rod has a sliding sleevewith two markers similar to the ones on the 5-lb DCP drivingrod for identifying the penetration distance and allowing thereadings to be taken near or at the surface of the hole.3.2.3 electronic readout unitin dynamic cone penetrom-eter, option
18、al readout device to automatically count the numberof hammer drops and penetration distance inside the soil.4. Summary of Test Method4.1 The 5-lb DCP is placed vertically and the drop hammeris used to penetrate the soil until the lower mark on the drivingrod is leveled with the surface of the soil.4
19、.2 The operator lifts the drop hammer to the upper stopdisk and releases it, allowing it to fall freely under gravity andstrike an anvil, causing the cone to be driven into the soil. Thenumber of drops needed to penetrate the cone a distance 3.25in. (83 mm) from the lower mark on the driving rod to
20、theupper one is counted.4.3 The number of drops is used to determine the pass or failof soil compaction based on the results of calibration testsbetween the number of drops and soil percent compaction insimilar soil of known percent compaction and water content.5. Significance and Use5.1 The test me
21、thod is used to assess the compaction effortof compacted materials. The number of drops required to drivethe cone a distance of 3.25 in. (83 mm) is used as a criterion todetermine the pass or fail in terms of soil percent compaction.5.2 The device does not measure soil compaction directlyand require
22、s determining the correlation between the numberof drops and percent compaction in similar soil of knownpercent compaction and water content.5.3 The number of drops is dependent on the soil watercontent. Calibration of the device should be performed at awater content equal to the water content expec
23、ted in the field.5.4 There are other DCPs with different dimensions, ham-mer weights, cone sizes, and cone geometries. Different testmethods exist for these devices (such as D 6951) and thecorrelations of the 5-lb DCP with soil percent compaction areunique to this device.5.5 The 5-lb DCP is a simple
24、 device, capable of beinghandled and operated by a single operator in field conditions. Itis typically used as Quality Control (QC) of layer-by-layercompaction by construction crew in roadway pavement, back-fill compaction in confined cuts and trenches, and utilitypavement restoration work.NOTE 2The
25、 quality of results produced by this test method isdependent on the competence of the personnel performing it and thesuitability of the equipment and facilities used. Agencies that meet thecriteria of Practice D 3740 are generally considered capable of competentand objective testing/sampling/inspect
26、ion/etc. Users of this standard arecautioned that compliance with Practice D 3740 does not in itself assurereliable results. Reliable results depend on many factors; Practice D 3740provides a means of evaluating some of these factors.6. Apparatus6.1 Aschematic diagram of the 5-lb DCPis shown in Fig.
27、 1.The device consists of an1116 6116 in. (17.5 6 1.6 mm) steelrod with a 5 6 0.2 lb (2.3 6 0.1 kg) drop hammer.The hammerdrops a distance 20 6 0.4 in. (508 6 10 mm) between theupper stop plate and the anvil.6.2 Driving RodThe driving rod has two permanentmarks or groves to monitor cone penetration
28、depth. The lowermark is at a distance 3 in. (83 mm) from the top surface ofthe cone and the distance between the two marks is 3.25 in. (83mm).6.3 Cone TipA replaceable cone tip of hardened steel orsimilar material with angle 25 6 2 degrees is placed at thebottom of the driving rod. Fig. 2 shows the
29、dimensions of thecone tip.6.4 Extension RodAn extension rod may be used tomonitor compaction in deep cuts and narrow trenches wherethe operator has to work from the ground surface. TheFIG. 1 Schematic Diagram of the 5-lb DCP DeviceD7380082extension rod should be of the same diameter and material ast
30、he driving rod. Fig. 3 shows a schematic of the device with theextension rod used in a confined hole.6.5 When the device is used in small holes and trenches, asleeve is used to monitor the penetration distance from thesurface as shown in Fig. 3. The lower mark on the sleeve isleveled with the ground
31、 surface using a straight edge and thesleeve is tightened by a screw to prevent it from moving duringthe test. Fig. 4 shows the dimensions of the sleeve.6.6 The addition of extensions will change the mass of thedevice and the energy delivered to the cone. When extensionrods and sleeves are used, cal
32、ibration tests should be performedwith these extensions attached to the device.6.7 An automated electronic data readout unit may be usedto register the number of drops and the penetrating distance.The system should give a signal and stop counting the numberof drops once the penetration equals the di
33、stance from thelower mark to the top one.6.8 The optional automated data readout unit should notinterfere with the operation and results of the device. Theoutput data of the system should satisfy the requirements ofdata reporting in Section 9.7. Calibration7.1 Device preparationThe device shall be i
34、nspected fordamaged parts before testing; the cone tip angle should not bedamaged and be within the acceptable tolerance before testing.FIG. 2 Dimensions of the Cone TipFIG. 3 Schematic of the 5-lb DCP with Extension Rod in ConfinedExcavationD73800837.2 Soil sample preparation:7.2.1 The soil percent
35、 compaction and optimum watercontent are determined for soil samples obtained from the fieldaccording to Test Method D 698 or D 1557 for laboratorycompaction characteristics of soil as per the project compactionspecifications.7.2.2 A soil sample is obtained from the field to filla2ft(610 mm) wide by
36、 2 ft long test pit with a depth of 12 in. (305mm). The test pit can be constructed in the site or in the lab.7.2.3 The soil is placed in the pit within 62 % of itsoptimum water content or as specified in the project compac-tion specifications. The soil water content in the pit is deter-mined using
37、Test Method D 2216 or D 6938.7.2.4 The soil is compacted in two lifts, 6 in. (150 mm) eachusing equal compaction effort in each lift. Initially, the soil iscompacted using a low compaction effort. The soil density ismeasured using Test Method D 6938 or D 1556.7.3 Setup of the coneThe operator holds
38、the devicevertically by the handle over the soil surface then lifts the drophammer and releases it to cause the cone to penetrate until thelower mark on the driving rod is leveled with the surface of thesoil layer.7.4 Cone testingThe operator lifts the drop hammer to theupper stop disk and releases
39、it, allowing it to fall freely undergravity. The hammer shall not unduly impact the upper diskwhen raised. The operator repeats the process and the numberof drops needed to advance the cone a distance 3.25 in. (83mm) is recorded.NOTE 3In stiff soils, where the number of drops between the marksexceed
40、s 20 drops at low compaction, the setup of the DCP test can beperformed by dropping the hammer until only the top surface of cone(instead of the lower mark) is leveled with the surface of the soil. Thetesting is then performed by counting the number of drops for the distanceof 3.25 in. (83 mm) betwe
41、en the top surface of the cone and the lowermark as shown in Fig. 1. Record the starting point of testing in the report.7.5 If the last drop needed to advance the cone 3.25 in. (83mm) overshoots the mark, then the last drop is not counted inthe total number of drops.7.6 The soil is removed from the
42、test pit, replaced, andcompacted using higher compaction efforts at the same watercontent. Steps 7.3 to 7.7 are repeated at higher compactionefforts until the compaction exceeds the specified percentcompaction required in the field.7.7 The number of hammer drops at each soil density isplotted agains
43、t the corresponding soil percent compaction asshown in Fig. 5. A minimum of four points should be used toestablish the calibration curve. At least one point should bewithin 2 % of the maximum percent compaction required in thefield.NOTE 4Calibration of the device should be performed on samplesFIG. 4
44、 Detail of the Sleeve Used with Extension RodFIG. 5 Calibration of No. of Drops with Soil Percent CompactionD7380084representing the field water content. Calibration should be repeated if thecalibration water content varies more than 62 % of the project standards.8. Procedure8.1 Test site preparatio
45、nRecord site information, backfilltype of each compacted lift, lift height, its optimum watercontent, and target percent compaction based on the standardor modified compaction tests in the lab.8.2 Verify and record field water content using Test MethodD 2216 or D 4959.8.3 Field testing at gradeThe o
46、perator performs steps 7.3to 7.7 as in the calibration procedure to determine the numberof hammer drops in the field.8.4 The total number of drops is compared with the targetnumber of drops at the same water content to establish thepass/fail compaction criteria. The pass criterion is establishedwhen
47、 the number of drops exceeds the target number of dropsobtained from calibration.8.5 It is recommended to use the device at least three timesat each test section and take the average drop count. Thereadings should be taken at a minimum distance of 6 in. (150mm) from each other. If a soft zone or the
48、 presence of a rockcauses one of the readings to be significantly different than theother readings in the layer, this reading should not be includedin the averaging and it should be repeated in another location.NOTE 5It is recommended to take more than three readings whentesting materials with high
49、variability such as soils containing gravel andgravel type soil.8.6 Testing a layer in a narrow trench below gradeAnextension rod is added to the driving rod when the device isused to monitor compaction in deep trenches. The sleeveshown in Fig. 4 is used if the operator cant see the markers onthe rod inside the narrow trench. The lower mark of the sleeveis aligned with the ground surface to match the alignment ofthe lower mark of the cone rod with the backfill layer as shownin Fig. 3.8.7 The operator performs the test as in Sections 7.3 to 7.7and records the n
