1、Designation: D 4394 04Standard Test Method forDetermining the In Situ Modulus of Deformation of RockMass Using the Rigid Plate Loading Method1This standard is issued under the fixed designation D 4394; the number immediately following the designation indicates the year oforiginal adoption or, in the
2、 case 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. Scope*1.1 This test method covers the preparation, equipment, testprocedure, and data reduction
3、 for determining in situ modulusof deformation of a rock mass using the rigid plate loadingmethod.1.2 This test method is designed to be conducted in an aditor small underground chamber; however, with suitable modi-fications it could be conducted at the surface.1.3 This test method is usually conduc
4、ted parallel or per-pendicular to the anticipated axis of thrust, as dictated by thedesign load.1.4 Time dependent tests can be performed but are to bereported in another standard.1.5 All observed and calculated values shall conform to theguidelines for significant digits and rounding established in
5、Practice D 6026.1.5.1 The method used to specify how data are collected,calculated, or recorded in this standard is not directly related tothe accuracy to which the data can be applied in design or otheruses, or both. How one applies the results obtained using thisstandard is beyond its scope.1.6 Th
6、e values stated in inch-pound units are to be regardedas the standard.1.7 The references appended to this standard contain furtherinformation on this test method.1.8 This standard does not purport to address all of thesafety concerns, if any, associated with its use. It is theresponsibility of the u
7、ser of this standard to establish appro-priate safety and health practices and determine the applica-bility of regulatory requirements prior to use. For specificprecaution statements, see Section 8.2. Referenced Documents2.1 ASTM Standards:2D 653 Terminology Relating to Soil, Rock and ContainedFluid
8、sD 2113 Practice for Diamond Core Drilling for Site Inves-tigationD 4395 Test Method for Determining the In Situ Modulusof Deformation of Rock Mass Using the Flexible PlateLoading MethodD 4403 Practice for Extensometers Used in RockD 4879 Guide for Geotechnical Mapping of Large Under-ground Openings
9、 in RockD 5079 Practices for Preserving and Transporting RockCore SampleD 5434 Guide for Field Logging of Subsurface Explora-tions of Soil and RockD 6026 Practice for Using Significant Digits in Geotechni-cal DataD 6032 Test Method for Determining Rock Quality Desig-nation (RQD) of Rock Core3. Termi
10、nology3.1 For terminology used in this test method, refer toTerminology, D 653.3.2 Definitions of Terms Specific to This Standard:3.2.1 deflectionmovement of the rigid plate, mortar pad,or rock in response to and in the same direction as the appliedload.3.2.2 loadtotal force acting on the rock face.
11、3.2.3 peak-to-peak modulus of deformationthe slope ofthe stress - strain curve line connecting the peaks of the curvesobtained from successive pressure cycles (see Fig. 1).3.2.4 recovery modulus of deformationthe tangent modu-lus of the unloading stress - strain curve. This modulus isusually higher
12、than the other moduli and is used in calculationswhere unloading conditions exist. The difference between thetangent and recovery moduli indicates that materials capacityof hysteresis or energy dissipation capabilities (see Fig. 2).3.2.5 rigid plateplate with deflection of less than 0.0001in. (0.002
13、5 mm) from center to edge of plate, when maximumload is applied.1This test method is under the jurisdiction of ASTM Committee D18 on Soil andRock and is the direct responsibility of Subcommittee D18.12 on Rock Mechanics.Current edition approved July 1, 2004. Published July 2004. Originally approvedi
14、n 1984. Last previous edition approved in 1998 as D 4394 84 (1998).2For referenced 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 we
15、bsite.1*A Summary of Changes section appears at the end of this standard.Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.3.2.6 secant modulus of deformationthe slope of thestress-strain curve between zero stress and any specified stre
16、ss.This modulus should be used for complete load steps from zeroto the desired load (see Fig. 2).3.2.7 tangent modulus of deformationthe slope of thestress - strain curve obtained over the segment of the loadingcurve judged by the investigator as the most representative ofelastic response. It neglec
17、ts the end effects of the curve and isbetter suited to small stress changes. The ratio between thesecant modulus and the tangent modulus can be used as ameans of measuring the stress damage of the material (see Fig.2).4. Summary of Test Method4.1 Areas on two opposing parallel faces of a test adit a
18、reflattened and smoothed.4.2 A mortar pad and rigid metal plate are installed againsteach face and a hydraulic loading system is placed between therigid plates.4.3 If deflection is to be measured within the rock mass,extensometer instruments shall be installed in the rock inaccordance with Practice
19、D 4403.4.4 The two faces are loaded and unloaded incrementallyand the deformations of the rock mass at the surfaces and, ifdesired, within the rock, are measured after each increment.The modulus of deformation is then calculated.5. Significance and Use5.1 Results of this type of test method are used
20、 to predictdisplacements in rock mass caused by loads from a structure orfrom underground construction. It is one of several tests thatshould be performed. The resulting in situ modulus is com-monly less than the elastic modulus determined in the labora-tory.5.2 The modulus is determined using an el
21、astic solution fora uniformly distributed load (uniform stress) over a circulararea acting on a semi-infinite elastic medium that produces aconstant normal displacement of the loaded surface area of themedium.5.3 This test method is normally performed at ambienttemperature, but equipment can be modi
22、fied or substituted foroperations at other temperatures.6. Interferences6.1 A completely inflexible plate used to load the rock faceis difficult to construct. However, if the plate is constructed asrigid as possible, the rock face is smoothed, and a thin,high-modulus material is used for the pad, th
23、e error is minimal.6.2 The rock under the loaded area is generally not homo-geneous, as assumed in theory. Rock will respond to the loadaccording to its local deformational characteristics. Therefore,deflection measurements at discrete points on the rock surfacetend to be heavily influenced by the d
24、eformational character-istics of the rock mass at that location and may give results thatare unrepresentative of the rock mass. The use of the averageplate deflection will mitigate this problem.6.3 Measurement of the deflection within the rock mass canutilize a finite gage length to reflect the aver
25、age rock massdeformation properties between the measuring points. Thisapproach entails three drawbacks, however. First, the rockmass is tested at very low stress levels unless the measurementpoints are very close to the rock surface, and because of this,the same problems as with surface measurements
26、 occur. Testsat low stress levels may give unrealistically low modulusvalues because microfractures, joints, and other discontinuitiesin the rock are open. Secondly, the disturbance caused byimplanting the deflection transducer in the rock mass is difficultto evaluate. The techniques in this test me
27、thod are designed toproduce minimal disturbance. Thirdly, in rocks with very highmodulus, the accuracy of the instruments may be insufficient toprovide reliable results.6.4 Time-rate of loading has negligible influence on themodulus.6.5 Calculations neglect the stress history of the rock.6.6 This te
28、st method is insensitive to Poissons ratio.6.7 Poissons ratio must be assumed or obtained fromlaboratory testing.7. Apparatus7.1 Equipment necessary for accomplishing this test methodincludes items for: preparing the test site, drilling and loggingFIG. 1 Rock Surface Deformation as a Function of Bea
29、ringPressureFIG. 2 Relationship Between Tangent, Secant and RecoveryModuliD4394042the instrumentation holes, measuring the rock deformation,applying and restraining test loads, recording test data, andtransporting various components to the test site.7.2 Test Site Preparation Equipment This shall inc
30、lude anassortment of excavation tools, such as drills and chippinghammers. Blasting shall not be allowed during final prepara-tion of the test site. The drill for the instrumentation holes shall,if possible, have the capability of retrieving cores from depthsof at least 30 ft (10 m).7.3 Borehole Vie
31、wing DeviceSome type of device isdesirable for examination of the instrumentation holes tocompare and verify geologic features observed in the core ifcore recovery is poor or if it is not feasible to retrieve orientedcores.7.4 Deformation Measuring Instruments Instruments formeasuring deformations s
32、hall include a reliable multiple-position borehole extensometer (MPBX) for each instrumen-tation hole and a tunnel diameter gage. For surface measure-ments, dial gages or linear variable differential transformers(LVDTs) are generally used. An accuracy of at least 60.0001in. (0.0025 mm), including th
33、e error of the readout equipment,and a sensitivity of at least 0.00005 in. (0.0013 mm) isrecommended. Errors in excess of 0.0004 in. (0.01 mm) caninvalidate test results when the modulus of rock mass exceeds5 3 106psi (3.5 3 104MPa).7.5 Loading EquipmentThe loading equipment includesthe device for a
34、pplying the load and the reaction members(usually thick-walled aluminum or steel pipes) which transmitthe load. Hydraulic rams or flatjacks are usually used to applythe load hydraulically with sufficient capability and volume toapply and maintain desired pressures to within 3 %. If flatjacksare used
35、 they should have sufficient range to allow fordeflection of the rock and should be constructed so that the twomain plates move apart in a parallel manner over the usableportion of the loading range. A spherical bearing of suitablecapacity should be coupled to one of the bearing plates.7.6 Load Cell
36、s and TransducersA load cell is recom-mended to measure the load on the bearing plate. An accuracyof at least 61000 lbf (64.4 kN), including errors introduced bythe readout system, and a sensitivity of at least 500 lbf (2.2 kN)are recommended. Alternatively, a pressure gage or transducermay be used
37、to monitor hydraulic pressure for calculation ofload, provided the device can measure the load to the samespecifications as the load cell. An accuracy of at least 620 psi(60.14 MPa), including error introduced by readout equip-ment, and a sensitivity of at least 10 psi (0.069 MPa). If ahydraulic ram
38、 is used, the effects of ram friction shall bedetermined. If flatjacks are used, care shall be taken that thejacks do not operate at the upper end of their range.7.7 Bearing PadsThe bearing pads shall have a modulusof elasticity of at least 4 3 106psi (3 3 104MPa) and shall becapable of conforming t
39、o the rock surface and bearing plate.High-early strength grout or molten sulfur bearing pads arerecommended.7.8 Bearing PlatesThe bearing plates shall approximate arigid die as closely as practical. A bearing plate that has beenfound satisfactory is shown on Fig. 3. Although the exactdesign and mate
40、rials may differ, the stiffness of the bearingplate shall at least be the minimum stiffness necessary toproduce no measurable deflection of the plate under maximumload.8. Safety Hazards8.1 All personnel involved in performing the test shall beformally prequalified under the quality assurance procedu
41、reslisted in Annex A1.8.2 Verify the compliance of all equipment and apparatuswith the performance specifications in Section 7. If no require-ments are stated, the manufacturers specifications for theequipment may be appropriate as a guide, however, care mustbe taken for sufficient performance. Perf
42、ormance verification isgenerally done by calibrating the equipment and measurementsystem. Accomplish calibration and documentation in accor-dance with the quality assurance procedures.8.3 Enforce safety by applicable safety standards. Pressurelines must be bled of air to preclude violent failure of
43、thepressure system. Total deformation should not exceed theexpansion capabilities of the flatjacks; normally this is approxi-mately 3 % of the diameter of a metal jack.9. In-Situ ConditionsNOTE 1The guidelines presented in this section are the domain of theagency or organization requesting the testi
44、ng and are intended to facilitatedefinition of the scope and development of site-specific requirements forthe testing program as a whole.9.1 Test each structurally distinctive zone of rock massselecting areas that are geologically representative of the mass.Test those portions of the rock mass with
45、features such asfaults, fracture zones, cavities, inclusions, and the like toevaluate their effects. Design the testing program so that effectsof local geology can be clearly distinguished.9.2 The size of the plate will be determined by localgeology, pressures to be applied, and the size of the adit
46、 to betested. These parameters should be considered prior to exca-vation of the adit. Optimum adit dimensions are approximatelysix times the plate diameter; recommended plate diameter iscommonly 112 to 314 ft (0.5 to 1 m). Other sizes are useddepending upon site specifics. A map of the adit and test
47、 siteshall be prepared in accordance with Guide D 4879.9.3 The affects of anisotropy should be investigated byappropriately oriented tests: for example, parallel and perpen-dicular to the bedding of a sedimentary sequence, or paralleland perpendicular to the long axes of columns in a basalt flow.9.4
48、 Tests shall be performed at a site not affected bystructural changes resulting from excavations of the adit. Thezone of rock that contributes to the measured deflection duringthe plate loading test depends on the diameter of the plate andthe applied load. Larger plates and higher loads measure ther
49、esponse of rock further away from the test adit. Thus, if therock around the adit is damaged by the excavation process, andthe deformational properties of the damaged zone are theprimary objective of the test program, small-diameter platetests on typically excavated surfaces are adequate. If theundisturbed in-situ modulus is desired, larger diameter platesand higher loads may be used, although practical consider-ations often limit the size of the equipment. Alternatively,careful excavation procedures, such as presplitting or otherD4394043types of smooth-wall blas
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