1、Designation: D6951/D6951M 09Standard Test Method forUse of the Dynamic Cone Penetrometer in ShallowPavement Applications1This standard is issued under the fixed designation D6951/D6951M; the number immediately following the designation indicates theyear of original adoption or, in the case of revisi
2、on, the year of last revision. A number in parentheses indicates the year of lastreapproval. A superscript epsilon () indicates an editorial change since the last revision or reapproval.1. Scope1.1 This test method covers the measurement of the pen-etration rate of the Dynamic Cone Penetrometer with
3、 an 8-kg17.6-lb hammer (8-kg 17.6-lb DCP) through undisturbedsoil or compacted materials, or both. The penetration rate maybe related to in situ strength such as an estimated in situ CBR(California Bearing Ratio). A soil density may be estimated(Note 1) if the soil type and moisture content are know
4、n. TheDCP described in this test method is typically used forpavement applications.1.2 The test method provides for an optional 4.6-kg10.1-lb sliding hammer when the use of the 8-kg 17.6-lbsliding mass produces excessive penetration in soft groundconditions.1.3 The values stated in either SI units o
5、r inch-pound unitsare to be regarded separately as standard. The values stated ineach system may not be exact equivalents; therefore, eachsystem shall be used independently of the other. Combiningvalues from the two systems may result in non-conformancewith the standard.1.4 This standard does not pu
6、rport 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 and health practices and determine the applica-bility of regulatory limitations prior to use.2. Terminology2.1 Definitions of Terms Speci
7、fic to This Standard:2.1.1 8-kg 17.6-lb DCP dynamic cone penetrometer withan 8-kg 17.6-lb hammer (see Fig. 1)a device used to assessthe in situ strength of undisturbed soil or compacted materials,or both.2.1.2 sliding attachment (see Fig. 1)an optional deviceused in reading the distance the DCP tip
8、has penetrated. It maybe fastened to the anvil or lower rod to hold/slide along aseparate measuring rod, or it may be fastened to the separaterod and slide along a graduated drive rod.3. Summary of Test Method3.1 The operator drives the DCP tip into soil by lifting thesliding hammer to the handle th
9、en releasing it. The total1This test method is under the jurisdiction of ASTM Committee E17 on Vehicle- Pavement Systems and is the direct responsibility of Subcommittee E17.41 onPavement Management and Data Needs.Current edition approved Nov. 1, 2009. Published December 2009. DOI:10.1520/D6951_D695
10、1M-09.FIG. 1 Schematic of DCP Device1Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.penetration for a given number of blows is measured andrecorded in mm/blow, which is then used to describe stiffness,estimate an in situ CBR strength
11、 from an appropriate correla-tion chart, or other material charcharacteristics.4. Significance and Use4.1 This test method is used to assess in situ strength ofundisturbed soil and compacted materials (or both). Thepenetration rate of the 8-kg 17.6-lb DCP can be used toestimate in-situ CBR (Californ
12、ia Bearing Ratio), to identifystrata thickness, shear strength of strata, and other materialcharacteristics.4.1.1 Other test methods exist for DCPs with differenthammer weights and cone tip sizes, which have correlationsthat are unique to the instrument.4.2 The 8-kg 17.6-lb DCP is held vertically an
13、d thereforeis typically used in horizontal construction applications, suchas pavements and floor slabs.4.3 This instrument is typically used to assess materialproperties down to a depth of 1000 mm 39 in. below thesurface. The penetration depth can be increased using drive rodextensions. However, if
14、drive rod extensions are used, careshould be taken when using correlations to estimate otherparameters since these correlations are only appropriate forspecific DCP configurations. The mass and inertia of the devicewill change and skin friction along drive rod extensions willoccur.4.4 The 8-kg 17.6-
15、lb DCP can be used to estimate thestrength characteristics of fine- and coarse-grained soils, granu-lar construction materials and weak stabilized or modifiedmaterials. The 8-kg 17.6-lb DCP cannot be used in highlystabilized or cemented materials or for granular materialscontaining a large percentag
16、e of aggregates greater than 50 mm2 in.4.5 The 8-kg 17.6-lb DCP can be used to estimate thestrength of in situ materials underlying a bound or highlystabilized layer by first drilling or coring an access hole.NOTE 1The DCP may be used to assess the density of a fairly uniformmaterial by relating den
17、sity to penetration rate on the same material. Inthis way undercompacted or “soft spots” can be identified, even thoughthe DCP does not measure density directly.24.5.1 A field DCP measurement results in a field or in situCBR and will not normally correlate with the laboratory orsoaked CBR of the sam
18、e material. The test is thus intended toevaluate the in situ strength of a material under existing fieldconditions.5. Apparatus5.1 The 8-kg 17.6-lb DCP is shown schematically in Fig.1. It consists of the following components: a 16-mm 58-in.diameter steel drive rod with a replaceable point or disposa
19、blecone tip, an 8-kg 17.6-lb hammer which is dropped a fixedheight of 575 mm 22.6 in., a coupler assembly, and a handle.The tip has an included angle of 60 degrees and a diameter atthe base of 20 mm 0.79 in. (See Fig. 2.)5.1.1 The apparatus is typically constructed of stainlesssteel, with the except
20、ion of the replacement point tip, whichmay be constructed from hardened tool steel or a similarmaterial resistant to wear.5.2 The following tolerances are recommended:5.2.1 Hammer weight-measurement of 8.0 kg 17.6 lb;tolerance is 0.01 kg 0.02 lb,5.2.2 Hammer weight-measurement of 4.6 kg 10.1 lb.;tol
21、erance is 0.01 kg 0.02 lb,5.2.3 Drop of hammer-measurement of 575 mm 22.6 in.;tolerance is 1.0 mm 0.04 in.,5.2.4 Tip angle measurement of 60 degrees included angle;tolerance is 1 degree, and5.2.5 Tip base diameter measurement of 20 mm 0.79 in.;tolerance is 0.25 mm 0.01 in.NOTE 2A disposable cone tip
22、 may be used. The deposable cone tip isheld in place with an o-ring, which allows the cone tip to be easilydetached when the drive rod is pulled upward after completion of the test.The disposable cone tip is shown schematically in Fig. 3.5.3 In addition to the DCP, the following equipment isneeded:5
23、.3.1 Tools for assembling the DCP,5.3.2 Lubricating Oil,5.3.3 Thread Locking Compound, and5.3.4 Data Recording form (see Table 1).5.4 Depending on the circumstances, the following equip-ment may also be needed or is recommended:5.4.1 A vertical scale graduated using increments of 1.0 mm0.04 in., or
24、measuring rod longer than the longest drive rod ifthe drive rod(s) are not graduated,5.4.2 An optional sliding attachment for use with a separatescale or measuring rod,5.4.3 A rotary hammer drill or coring apparatus capable ofdrilling a minimum diameter hole of 25 mm 1 in. A largerhole may be requir
25、ed depending on the underlying material orthe need for addition tests or sampling,5.4.4 A wet/dry vacuum or suitable alternative to removeloose material and fluid if an access hole is made beforetesting,2“METHOD ST6: Measurement of the In Situ Strength of Soils by the DynamicCone Penetrometer (DCP),
26、 Special Methods for Testing Roads,” Draft TMH6,Technical Methods for Highways (TMH), Pretoria, SouthAfrica, ISBN 0 7988 22899, 1984, p. 20. FIG. 2 Replaceable Point TipD6951/D6951M 0925.4.5 Field power supply to power items in 5.4.3 and 5.4.4,5.4.6 Disposable cone tips,5.4.7 Dual mass hammer (see F
27、ig. 4), and5.4.8 Extraction jack, recommended if disposable cone tipsare not used (see Fig. 5).NOTE 3A 4.6-kg 10-lb hammer (see Fig. 4) may be used in place ofthe 8-kg 18-lbf hammer provided that the standard drop height ismaintained. The 4.6-kg 10-lbf hammer is used in weaker materialswhere the 8-k
28、g 18-lbf hammer would produce excessive penetration.NOTE 4An automated version of the DCP (ADCP) may be usedprovided all requirements of this standard with respect to the apparatusand procedure are met.NOTE 5An automated data collection system may be used provided itmeasures and records to the neare
29、st 1 mm 0.04 in. and does not interferewith the operation/results of the devise.6. Procedure6.1 Equipment CheckBefore beginning a test, the DCPdevice is inspected for fatigue-damaged parts, in particular thecoupler and handle, and excessive wear of the drive rod andreplaceable point tip. All joints
30、must be securely tightenedincluding the coupler assembly and the replaceable point tip (orthe adapter for the disposable cone tip) to drive rod.6.2 Basic OperationThe operator holds the device by thehandle in a vertical or plumb position and lifts and releases thehammer from the standard drop height
31、. The recorder measuresand records the total penetration for a given number of blowsor the penetration per blow.6.3 Initial Reading:6.3.1 Testing a Surface LayerThe DCP is held verticallyand the tip seated such that the top of the widest part of the tipis flush with the surface of the material to be
32、 tested. An initialreading is obtained from the graduated drive rod or a separatevertical scale/measuring rod. The distance is measured to thenearest 1 mm 0.04 in. Some sliding reference attachmentsallow the scale/measuring rod to be set/marked at zero whenthe tip is at the zero point shown in Fig.
33、2.6.3.2 Testing Below a Bound LayerWhen testing materi-als underlying a bound layer, a rotary hammer drill or coringapparatus meeting the requirements given in 5.4.3 above isused to provide an access hole to the layer to be tested. Wetcoring requires that coring fluid be removed immediately andthe D
34、CP test be performed as soon as possible, but not longerthan 10 minutes following completion of the coring operation.The coring fluid must not be allowed to soak into or penetratethe material to be tested. A wet/dry vacuum or suitablealternative is used after completion of drilling or coring toremov
35、e loose materials and fluid from the access hole beforetesting. To minimize the extent of the disturbance from therotary hammer, drilling should not be taken completely throughthe bound layer, but stopped short by about 10 to 20 mm 0.4to 0.8 in. The DCP is then used to penetrate the bottomportion of
36、 the bound layer. This can be a repetitive processbetween drilling and doing DCP tests to determine the thick-ness of the layer.6.3.3 Testing Pavement With Thin SealsFor pavementswith thin seals, the tip is advanced through the seal until thezero point (see Fig. 4) of the tip is flush with the top o
37、f the layerto be tested.6.3.4 Once the layer to be tested has been reached, areference reading is taken with the zero point at the top of thatlayer and the thickness of the layer(s) cored through recorded.This reference reading is the point from which the subsequentpenetration is measured.6.4 Testin
38、g Sequence:6.4.1 Dropping the HammerThe DCP device is held in avertical or plumb position. The operator raises the hammeruntil it makes only light contact with the handle. The hammershall not impact the handle when being raised. The hammer isthen allowed to free-fall and impact the anvil coupler ass
39、embly.The number of blows and corresponding penetrations arerecorded as described in 6.5.6.4.2 Depth of PenetrationThe depth of penetration willvary with application. For typical highway applications, apenetration less than 900 mm 35 in. will generally beadequate.6.4.3 RefusalThe presence of large a
40、ggregates or rockstrata will either stop further penetration or deflect the driverod. If after 5 blows, the device has not advanced more than 2mm 0.08 in. or the handle has deflected more than 75 mm 3in. from the vertical position, the test shall be stopped, and thedevice moved to another test locat
41、ion. The new test locationshould be a minimum of 300 mm 12 in. from the priorlocation to minimize test error caused by disturbance of thematerial.6.4.4 ExtractionFollowing completion of the test, thedevice should be extracted using the extraction jack whenusing a replaceable point tip. When using a
42、disposable cone,the device is extracted by driving the hammer upward againstthe handle.6.5 Data Recording:6.5.1 A form like the one shown in Table 1 is suggested fordata recording. The recorder enters the header informationbefore the test. The actual test data are recorded in column 1(Number of Blow
43、s) and column 2 (Cumulative Penetration inmm); if the moisture content is available, it is entered incolumn 8. When testing a subsurface layer though a drilled orcored access hole, the first reading corresponds to the refer-enced reading at the top of the layer to be tested as per 6.3.2.The number o
44、f blows between readings may be varied depend-ing on the resistance of the material. Normally readings will betaken after a fixed number of blows, that is, 1 blow for softFIG. 3 Disposable Cone TipD6951/D6951M 093material, 5 blows for “normal” materials and 10 blows for veryresistive materials. The
45、penetration to the nearest 1 mm 0.04in. corresponding to a specific number of blows is recorded. Areading is taken immediately when the material properties orpenetration rate change significantly.7. Calculations and Interpretation of Results7.1 The estimated in situ CBR is computed using the DCPinde
46、x (column 6, Table 1) and Table 2 for each set of readings.The penetration per blow may then be plotted against scalereading or total depth. The penetration per blow is then used toestimate in situ CBR or shear strength using the appropriatecorrelation. For example, the correlation of penetration pe
47、rblow (DCP) in Table 2 is derived from the following equationrecommended by the US Army Corps of Engineers:3CBR 5 292 / DCP1.12for DCP in mm/blow (1)CBR 5 292 / DCP 3 25.4!1.12for DCP in in./blow (2)The above equation is used for all soils except for CL soilsbelow CBR 10 and CH soils. For these soil
48、s, the followingequations are recommended by the US Army Corps of Engi-neers:4CBR 5 1/0.017019 3 DCP!2for DCP in mm/blow (3)CBR 5 1/0.432283 3 DCP!2for DCP in in./blow (4)for CL soils with CBR 324 0.5AFor DCP Index in units of in./blow, divide by 25.4.D6951/D6951M 095BIBLIOGRAPHY(1) Ayers, M. E., “R
49、apid Shear Strength of In Situ Granualr MaterialsUtilizing the Dynamic Cone Penetrometer,” Ph.D. Theses, Univer-sity of Illinois, Urbana, IL, 1990.(2) De Beer, M., Kleyn, E. G., and Savage P. F., “Towards aClassification System for the Strength-Balance of Thin SurfacedFlexible Pavements,” Proceedings of the 1988 Annual Transpor-tation Convention (ATC 88), Session S.443, Vol 3D, Paper 3D-4,Pretoria, July 1988.(3) De Beer, M., “Dynamic Cone Penetrometer (DCP)Aided Evolutionof the
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