1、Designation: D4394 17Standard Test Method forDetermining In Situ Modulus of Deformation of Rock MassUsing Rigid Plate Loading Method1This standard is issued under the fixed designation D4394; the number immediately following the designation indicates the year oforiginal adoption or, in the case of r
2、evision, the year of last revision. A number in parentheses indicates the year of last reapproval. Asuperscript epsilon () 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 for determ
3、ining 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 conducted paralle
4、l or per-pendicular to the anticipated axis of thrust, as dictated by thedesign load and to diametrically opposite surfaces.1.4 Both instantaneous deformation and primary creep canbe obtained from this test method.1.5 Time dependent tests can be performed and are dis-cussed briefly here but are to b
5、e reported in another standard.1.6 Observed and calculated values shall conform to theguidelines for significant digits and rounding established inPractice D6026.1.6.1 The method used to specify how data are collected,calculated, or recorded in this standard is not directly related tothe accuracy to
6、 which the data can be applied in design or otheruses, or both. How one applies the results obtained using thisstandard is beyond its scope.1.7 The values stated in inch-pound units are to be regardedas standard. The values given in parentheses are mathematicalconversions to SI units that are provid
7、ed for information onlyand are not considered standard.1.8 The references appended to this standard contain furtherinformation on this test method.1.9 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 sta
8、ndard to establish appro-priate safety and health practices and determine the applica-bility of regulatory requirements prior to use. For specificprecaution statements, see Section 8.1.10 This international standard was developed in accor-dance with internationally recognized principles on standard-
9、ization established in the Decision on Principles for theDevelopment of International Standards, Guides and Recom-mendations issued by the World Trade Organization TechnicalBarriers to Trade (TBT) Committee.2. Referenced Documents2.1 ASTM Standards:2D653 Terminology Relating to Soil, Rock, and Conta
10、inedFluidsD2113 Practice for Rock Core Drilling and Sampling ofRock for Site ExplorationD3740 Practice for Minimum Requirements for AgenciesEngaged in Testing and/or Inspection of Soil and Rock asUsed in Engineering Design and ConstructionD4395 Test Method for Determining In Situ Modulus ofDeformati
11、on of Rock Mass Using Flexible Plate LoadingMethodD4403 Practice for Extensometers Used in RockD4879 Guide for Geotechnical Mapping of Large Under-ground Openings in Rock (Withdrawn 2017)3D5079 Practices for Preserving and Transporting Rock CoreSamples (Withdrawn 2017)3D5434 Guide for Field Logging
12、of Subsurface Explorationsof Soil and RockD6026 Practice for Using Significant Digits in GeotechnicalDataD6032 Test Method for Determining Rock Quality Designa-tion (RQD) of Rock Core3. Terminology3.1 Definitions:1This test method is under the jurisdiction ofASTM Committee D18 on Soil andRock and is
13、 the direct responsibility of Subcommittee D18.12 on Rock Mechanics.Current edition approved July 1, 2017. Published August 2017. Originallyapproved in 1984. Last previous edition approved in 2008 as D4394 08. DOI:10.1520/D4394-17.2For referenced ASTM standards, visit the ASTM website, www.astm.org,
14、 orcontact ASTM Customer Service at serviceastm.org. For Annual Book of ASTMStandards volume information, refer to the standards Document Summary page onthe ASTM website.3The last approved version of this historical standard is referenced onwww.astm.org.*A Summary of Changes section appears at the e
15、nd of this standardCopyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United StatesThis international standard was developed in accordance with internationally recognized principles on standardization established in the Decision on Principles for theD
16、evelopment of International Standards, Guides and Recommendations issued by the World Trade Organization Technical Barriers to Trade (TBT) Committee.13.1.1 For terminology used in this test method, refer toTerminology, D653.3.2 Definitions of Terms Specific to This Standard:3.2.1 deflection, nmoveme
17、nt of the rigid plate, mortarpad, or rock in response to and in the same direction as theapplied load.3.2.2 peak-to-peak modulus of deformation, nthe slope ofthe stress - strain curve line connecting the peaks of the curvesobtained from successive pressure cycles (see Fig. 1).3.2.3 recovery modulus
18、of deformation, nthe tangentmodulus of the unloading stress - strain curve. This modulus isusually higher 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
19、dissipation capabilities (see Fig. 2).3.2.4 rigid plate, nplate with deflection of less than0.0001 in. (0.0025 mm) from center to edge of plate, whenmaximum load is applied.3.2.5 secant modulus of deformation, nthe slope of thestress-strain curve between zero stress and a specified stress.This modul
20、us should be used for the load steps from zero to thedesired load (see Fig. 2).3.2.6 tangent modulus of deformation, nthe slope of thestress - strain curve obtained over the segment of the loadingcurve judged by the investigator as the most representative ofelastic response. It neglects the end effe
21、cts 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 orunderground ch
22、amber are flattened 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 P
23、ractice D4403.4.4 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 load andunload increment. The modulus of deformation (Secant, Tan-gent and/or Recovery) is then calculated on those segm
24、ents ofthe data plot pertinent to the data acquisition program.5. Significance and Use5.1 Results of this type of test method are used to predictdisplacements in rock mass caused by loads from a structure orfrom underground construction. It is one of several tests thatshould be performed. The result
25、ing in situ elastic modulus iscommonly less than the elastic modulus determined in thelaboratory.5.2 The modulus is determined using an elastic solution fora uniformly distributed load (uniform stress) over a circulararea acting on a semi-infinite elastic medium that produces aconstant normal displa
26、cement of the loaded surface area of themedium.5.3 This test method is normally performed at ambienttemperature, but equipment can be modified or substituted foroperations at other temperatures.NOTE 1The quality of the result produced by this standard isdependent on the competence of the personnel p
27、erforming it, and thesuitability of the equipment and facilities used. Agencies that meet thecriteria of Practice D3740 are generally considered capable of competentand objective testing/sampling/inspection/etc. Users of this standard arecautioned that compliance with Practice D3740 does not in itse
28、lf assurereliable results. Reliable results depend on many factors; Practice D3740provides a means of evaluating some of those factors.FIG. 1 Rock Surface Deformation as a Function of Bearing Pres-sure and Increasing Loading CyclesArrows show up and direc-tion of cycles and line shows Peak to Peak M
29、odulus.FIG. 2 Relationship Between Tangent, Secant and RecoveryModuli for a Single Cycle of Loading and UnloadingD4394 1726. Interferences6.1 An inflexible plate used to load the rock face is difficultto construct. However, if the plate is constructed as rigid aspracticable, the rock face is smoothe
30、d, and a thin, high-modulus material is used for the pad, the error is minimal.6.2 The rock under the loaded area is generally nothomogeneous, as assumed in theory. Rock will respond to theload according to its local deformational characteristics.Therefore, deflection measurements at discrete points
31、 on therock surface tend to be heavily influenced by the deformationalcharacteristics of the rock mass at that location and may giveresults that are unrepresentative of the rock mass. The use ofthe average plate deflection will mitigate this problem.6.3 Measurement of the deflection within the rock
32、mass canutilize a finite gauge length to reflect the average 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 becau
33、se of this,the same problems as with surface measurements 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 mas
34、s is difficultto evaluate. The techniques in this test method 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 Calcul
35、ations neglect the stress history of the rock.6.6 This test method is insensitive to Poissons ratio.6.7 Poissons ratio should be assumed or obtained fromlaboratory testing.7. Apparatus7.1 Equipment necessary for accomplishing this test methodincludes items for: preparing the test site, drilling and
36、loggingthe 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 EquipmentThis shall include anassortment of excavation tools, such as drills, drill bits, andchippi
37、ng hammers. Blasting shall not be allowed during apreparation of the test site. The drill for the instrumentationholes shall, if practicable, have the capability of retrievingcores from depths of about 30 ft (10 m).7.3 Borehole Viewing DeviceSome type of device isdesirable for observation of the ins
38、trumentation 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 InstrumentsInstruments formeasuring deformations shall include a reliable multiple-position borehole extensometer (MPBX)
39、 for each instrumen-tation hole and a tunnel diameter gauge. For surfacemeasurements, dial gages or linear variable differential trans-formers (LVDTs) are generally used. An accuracy of 60.0001in. (0.0025 mm), including the error of the readout equipment,and a sensitivity of at least 0.00005 in. (0.
40、0013 mm) isrecommended. Errors in excess of 0.0004 in. (0.01 mm) caninvalidate test results when the modulus of rock mass exceeds5106psi (3.5 104MPa).7.5 Loading EquipmentThe loading equipment includesthe device for applying the load and the reaction members(usually thick-walled aluminum or steel pi
41、pes) which transmitthe load of sufficient capacity for the intended test program.Hydraulic rams or flatjacks are usually used to apply the loadhydraulically with sufficient capability and volume to applyand maintain desired pressures to within 3 %. If flatjacks areused they should have sufficient ra
42、nge to allow for deflection ofthe rock and should be constructed so that the two main platesmove apart in a parallel manner over the usable portion of theloading range. A spherical bearing of suitable capacity shouldbe coupled to one of the bearing plates.7.6 Load Cells and TransducersA load cell is
43、 recom-mended to measure the load on the bearing plate. An accuracyof around 61000 lbf (64.4 kN), including errors introduced bythe readout system, and a sensitivity of 500 lbf (2.2 kN) arerecommended. Alternatively, a pressure gauge or transducermay be used to monitor hydraulic pressure for calcula
44、tion ofload, provided the device can measure the load to the samespecifications as the load cell. An accuracy of 620 psi (60.14MPa), including error introduced by readout equipment, and asensitivity of 10 psi (0.069 MPa). If a hydraulic ram is used,the effects of ram friction shall be determined. If
45、 flatjacks areused, care shall be taken that the jacks do not operate at theupper end of their range.7.7 Bearing PadsThe bearing pads shall have a modulusof elasticity of around 4 106psi (3 104MPa) and shall becapable of conforming to the rock surface and bearing plate.High-early strength grout or m
46、olten 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 materials may differ, the stiffness of the bearingplate shall be the mi
47、nimum stiffness necessary to not producemeasurable deflection of the plate under maximum load.8. Safety Hazards8.1 Enforce safety by applicable safety standards.8.2 Pressure lines should be bled of air to preclude violentfailure of the pressure system.8.3 Total deformation should not exceed the expa
48、nsioncapabilities of the flatjacks; normally this is approximately 3 %of the diameter of a metal jack.9. In-Situ ConditionsNOTE 2The guidelines presented in this section are the domain of theagency or organization requesting the testing and are intended to facilitatedefinition of the scope and devel
49、opment of site-specific requirements forD4394 173the 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 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 to
