1、Designation: D 6951 03Standard Test Method forUse of the Dynamic Cone Penetrometer in ShallowPavement Applications1This standard is issued under the fixed designation D 6951; the number immediately following the designation indicates the year oforiginal adoption or, in the case of revision, the year
2、 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 measurement of the pen-etration rate of the Dynamic Cone Penetrometer with an 8-kgham
3、mer (8-kg DCP) through undisturbed soil and/or com-pacted materials. The penetration rate may be related to in situstrength such as an estimated in situ CBR (California BearingRatio).Asoil density may be estimated (Note 1) if the soil typeand moisture content are known. The DCPdescribed in this test
4、method is typically used for pavement applications.1.2 The test method provides for an optional 4.6-kg slidinghammer when the use of the 8-kg sliding mass producesexcessive penetration in soft ground conditions.1.3 This standard does not purport to address all of thesafety concerns, if any, associat
5、ed 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 Specific to This Standard:2.1.1 8-kg DCP dynamic cone penetromete
6、r with an 8 kghammer (see Fig. 1)a device used to assess the in situstrength of undisturbed soil and/or compacted materials.2.1.2 sliding attachment (see Fig. 1)an optional deviceused in reading the distance the DCP tip has penetrated. It maybe fastened to the anvil or lower rod to hold/slide along
7、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 then releasing it. The totalpenetration for a given number of blows is measured an
8、drecorded in mm/blow, which is then used to describe stiffness,estimate an in situ CBR strength from an appropriate correla-tion chart, or other material charcharacteristics.1This test method is under the jurisdiction of ASTM Committee E17 onVehicle-Pavement Systems and is the direct responsibility
9、of Subcommittee E17.41on Pavement Management.Current edition approved May 10, 2003. Published June 2003.FIG. 1 Schematic of DCP Device1Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.4. Significance and Use4.1 This test method is used
10、 to assess in situ strength ofundisturbed soil and/or compacted materials. The penetrationrate of the 8-kg DCP can be used to estimate in-situ CBR(California Bearing Ratio), to identify strata thickness, shearstrength of strata, and other material characteristics.4.1.1 Other test methods exist for D
11、CPs with differenthammer weights and cone tip sizes, which have correlationsthat are unique to the instrument.4.2 The 8-kg DCP is held vertically and therefore istypically used in horizontal construction applications, such aspavements and floor slabs.4.3 This instrument is typically used to assess m
12、aterialproperties down to a depth of 1000-mm (39-in.) below thesurface. The penetration depth can be increased using drive rodextensions. However, if drive rod extensions are used, careshould be taken when using correlations to estimate otherparameters since these correlations are only appropriate f
13、orspecific DCP configurations. The mass and inertia of the devicewill change and skin friction along drive rod extensions willoccur.4.4 The 8-kg DCP can be used to estimate the strengthcharacteristics of fine- and coarse-grained soils, granular con-struction materials and weak stabilized or modified
14、 materials.The 8-kg DCP cannot be used in highly stabilized or cementedmaterials or for granular materials containing a large percent-age of aggregates greater than 50-mm (2-in.).4.5 The 8-kg DCP can be used to estimate the strength of insitu materials underlying a bound or highly stabilized layer b
15、yfirst drilling or coring an access hole.NOTE 1The DCPmay be used to assess the density of a fairly uniformmaterial by relating density 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
16、 field DCP measurement results in a field or in situCBR and will not normally correlate with the laboratory orsoaked CBR of the same material. The test is thus intended toevaluate the in situ strength of a material under existing fieldconditions.5. Apparatus5.1 The 8-kg DCP is shown schematically in
17、 Fig. 1.Itconsists of the following components: a 15.8-mm (58-in.)diameter steel drive rod with a replaceable point or disposablecone 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
18、diameter atthe base of 20-mm (0.79-in.). (See Fig. 2.)5.1.1 The apparatus is typically constructed of stainlesssteel, with the exception 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:
19、5.2.1 Hammer weight-measurement of 8.0-kg (17.6-lb);tolerance is 0.010-kg (0.022-lb),5.2.2 Hammer weight-measurement of 4.6-kg (10.1-lb.);tolerance is 0.010-kg (0.022-lb),5.2.3 Drop of hammer-measurement of 575-mm (22.6-in.);tolerance is 1.0-mm (0.039-in.),5.2.4 Tip angle measurement of 60 degrees i
20、ncluded angle;tolerance is 1 degree, and5.2.5 Tip base diameter measurement of 20-mm (0.790-in.);tolerance is 0.25-mm (0.010-in.)NOTE 2A disposable cone tip 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
21、 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:5.3.1 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
22、on the circumstances, the following equip-ment may also be needed or is recommended:5.4.1 Avertical scale graduated using increments of 1.0-mm(0.04-in.), or measuring rod longer than the longest drive rod ifthe drive rod(s) are not graduated,2“METHOD ST6: Measurement of the In Situ Strength of Soils
23、 by the DynamicCone Penetrometer (DCP), 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 TipFIG. 3 Disposable Cone TipD69510325.4.2 An optional sliding attachment for use with a separat
24、escale 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 required depending on the underlying material orthe need for addition tests or sampling,5.4.4 A wet/dry vacuum or suitable alternative to removeloo
25、se material and fluid if an access hole is made beforetesting,5.4.5 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 Fig. 4), and5.4.8 Extraction jack, recommended if disposable cone tipsare not used (see Fig. 5).NOTE 3A 4.6-kg (10.1-lb) ham
26、mer (see Fig. 4) may be used in placeof the 8-kg (17.6-lb) hammer provided that the standard drop height ismaintained. The 4.6-kg (10.1-lb) hammer is used in weaker materialswhere the 8-kg (17.6-lb) hammer would produce excessive penetration.NOTE 4An automated version of the DCP (ADCP) may be usedpr
27、ovided 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 nearest 1-mm (0.04-in.) and does not interferewith the operation/results of the devise.6. Procedure6.1 Equipment Ch
28、eckBefore 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 must be securely tightenedincluding the coupler assembly and the replaceable point tip (orthe adapter for th
29、e 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. The recorder measuresand records the total penetration for a given number of blowsor the penetration per b
30、low.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 tested. An initialreading is obtained from the graduated drive rod or a separatevertical scale/measuring ro
31、d. 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. 2.6.3.2 Testing Below a Bound LayerWhen testing materi-als underlying a bound layer, a rotary hammer dril
32、l 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 DCP test be performed as soon as possible, but not longerthan 10 min following completion of the coring op
33、eration. Thecoring fluid must not be allowed to soak into or penetrate thematerial to be tested. A wet/dry vacuum or suitable alternativeis used after completion of drilling or coring to remove loosematerials and fluid from the access hole before testing. Tominimize the extent of the disturbance fro
34、m the rotary hammer,drilling should not be taken completely through the boundlayer, but stopped short by about 10- to 20-mm. The DCP isthen used to penetrate the bottom portion of the bound layer.This can be a repetitive process between drilling and doingDCP tests to determine the thickness of the l
35、ayer.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 of the layerto be tested.6.3.4 Once the layer to be tested has been reached, areference reading is taken with the zero point
36、 at the top of thatTABLE 1 DCP Data Sheet3Project: Forest Service RoadLocation: STA 30+50, 1 M RT of C/LDepth of zero point below Surface:0Material Classification: GW/CLPavement conditions: Not applicableDate: 7 July 2001Personnel: JLS 2 for 4.6-kg (10.1-lb) hammer.FFootnote D 3 Footnote E.GFrom CBR
37、 versus DCP Index correlation.H% Moisture content when available.D6951033layer and the thickness of the layer(s) cored through recorded.This reference reading is the point from which the subsequentpenetration is measured.6.4 Testing Sequence:6.4.1 Dropping the HammerThe DCP device is held in avertic
38、al 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 assembly.The number of blows and corresponding penetrations arerecorded
39、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 be ad-equate.6.4.3 RefusalThe presence of large aggregates or rockstrata will either stop further penetration or d
40、eflect the driverod. If after 5 blows, the device has not advanced more than2-mm (0.08-in.) or the handle has deflected more than 75-mm(3-in.) from the vertical position, the test shall be stopped, andthe device moved to another test location. The new test locationshould be a minimum of 300-mm (12-i
41、n.) 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 disposable cone,the device is extracted by driving the hamm
42、er 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 Blows) and column 2 (Cumulative Penetration inmm); if the moist
43、ure content is available, it is entered incolumn 8. When testing a subsurface layer though a drilled orFIG. 4 Schematic of Dual-Mass HammerFIG. 5 Schematic of DCP Extraction JackD6951034cored access hole, the first reading corresponds to the refer-enced reading at the top of the layer to be tested a
44、s per 6.3.2.The number of 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 softmaterial, 5 blows for “normal” materials and 10 blows for veryresistive materials. The penetration to the
45、 nearest 1-mm (0.04-in.) 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 DCPindex (column 6, Ta
46、ble 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 perblow (DCP) in
47、Table 2 is derived from the equation CBR = 292/ DCP1.12recommended by the US Army Corps of Engineers.3This equation is used for all soils except for CL soils belowCBR 10 and CH soils. For these soils, the following equationsare recommended by the US Army Corps of Engineers:4CL soils CBR 324 0.5D6951
48、035BIBLIOGRAPHY(1) Ayers, M. E., “Rapid 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 Surf
49、acedFlexible Pavements,” Proceedings of the 1988 Annual Transporta-tion 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 Behaviour of Pavements with Lightly Cementitious Layers,”Division of Roads and Transport Technology, Research ReportDPVT-37, CSIR, Pretoria, South Africa, April 1989.(4) De Beer, M., Kleyn, E. G., and Savage, P. F., “Advances inPavement Evaluation and Overlay Design with the Aid of theDynamic Cone Penetrometer (DCP),” 2nd International Sympo-sium on Pave
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