1、Designation: D4394 08D4394 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 c
2、ase of revision, 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, test procedure, and data reduction f
3、or determining in situ modulus ofdeformation of a rock mass using the rigid plate loading method.1.2 This test method is designed to be conducted in an adit or small underground chamber; however, with suitable modificationsit could be conducted at the surface.1.3 This test method is usually conducte
4、d parallel or perpendicular to the anticipated axis of thrust, as dictated by the designload.load and to diametrically opposite surfaces.1.4 Both instantaneous deformation and primary creep can be obtained from this test method.1.5 Time dependent tests can be performed and are discussed briefly here
5、 but are to be reported in another standard.1.6 Observed and calculated values shall conform to the guidelines for significant digits and rounding established in PracticeD6026.1.6.1 The method used to specify how data are collected, calculated, or recorded in this standard is not directly related to
6、 theaccuracy to which the data can be applied in design or other uses, or both. How one applies the results obtained using this standardis beyond its scope.1.7 The values stated in inch-pound units are to be regarded as standard. The values given in parentheses are mathematicalconversions to SI unit
7、s that are provided for information only and are not considered standard.1.8 The references appended to this standard contain further information on this test method.1.9 This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibilityof
8、the user of this standard to establish appropriate safety and health practices and determine the applicability of regulatoryrequirements prior to use. For specific precaution statements, see Section 8.1.10 This international standard was developed in accordance with internationally recognized princi
9、ples on standardizationestablished in the Decision on Principles for the Development of International Standards, Guides and Recommendations issuedby the World Trade Organization Technical Barriers to Trade (TBT) Committee.2. Referenced Documents2.1 ASTM Standards:2D653 Terminology Relating to Soil,
10、Rock, and Contained FluidsD2113 Practice for Rock Core Drilling and Sampling of Rock for Site ExplorationD3740 Practice for Minimum Requirements for Agencies Engaged in Testing and/or Inspection of Soil and Rock as Used inEngineering Design and ConstructionD4395 Test Method for Determining In Situ M
11、odulus of Deformation of Rock Mass Using Flexible Plate Loading MethodD4403 Practice for Extensometers Used in RockD4879 Guide for Geotechnical Mapping of Large Underground Openings in Rock (Withdrawn 2017)3D5079 Practices for Preserving and Transporting Rock Core Samples (Withdrawn 2017)31 This tes
12、t method is under the jurisdiction of ASTM Committee D18 on Soil and Rock and is the direct responsibility of Subcommittee D18.12 on Rock Mechanics.Current edition approved July 1, 2008July 1, 2017. Published August 2008August 2017. Originally approved in 1984. Last previous edition approved in 2004
13、2008 asD4394 04.D4394 08. DOI: 10.1520/D4394-08.10.1520/D4394-17.2 For referencedASTM standards, visit theASTM website, www.astm.org, or contactASTM Customer Service at serviceastm.org. For Annual Book of ASTM Standardsvolume information, refer to the standards Document Summary page on the ASTM webs
14、ite.3 The last approved version of this historical standard is referenced on www.astm.org.This document is not an ASTM standard and is intended only to provide the user of an ASTM standard an indication of what changes have been made to the previous version. Becauseit may not be technically possible
15、 to adequately depict all changes accurately, ASTM recommends that users consult prior editions as appropriate. In all cases only the current versionof the standard as published by ASTM is to be considered the official document.*A Summary of Changes section appears at the end of this standardCopyrig
16、ht ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States1D5434 Guide for Field Logging of Subsurface Explorations of Soil and RockD6026 Practice for Using Significant Digits in Geotechnical DataD6032 Test Method for Determining Rock Quality Designati
17、on (RQD) of Rock Core3. Terminology3.1 For terminology used in this test method, refer to Terminology, D653.Definitions:3.1.1 For terminology used in this test method, refer to Terminology, D653.3.2 Definitions of Terms Specific to This Standard:3.2.1 deflectiondeflection, nmovement of the rigid pla
18、te, mortar pad, or rock in response to and in the same direction as theapplied load.3.2.2 loadtotal force acting on the rock face.3.2.2 peak-to-peak modulus of deformationdeformation, nthe slope of the stress - strain curve line connecting the peaks ofthe curves obtained from successive pressure cyc
19、les (see Fig. 1).3.2.3 recovery modulus of deformationdeformation, nthe tangent modulus of the unloading stress - strain curve. Thismodulus is usually higher than the other moduli and is used in calculations where unloading conditions exist. The differencebetween the tangent and recovery moduli indi
20、cates that materials capacity of hysteresis or energy dissipation capabilities (see Fig.2).3.2.4 rigid plateplate, nplate with deflection of less than 0.0001 in. (0.0025 mm) from center to edge of plate, whenmaximum load is applied.3.2.5 secant modulus of deformationdeformation, nthe slope of the st
21、ress-strain curve between zero stress and a specifiedstress. This modulus should be used for the load steps from zero to the desired load (see Fig. 2).3.2.6 tangent modulus of deformationdeformation, nthe slope of the stress - strain curve obtained over the segment of theloading curve judged by the
22、investigator as the most representative of elastic response. It neglects the end effects of the curve andFIG. 1 Rock Surface Deformation as a Function of Bearing Pressure and Increasing Loading CyclesArrows show up and direction ofcycles and line shows Peak to Peak Modulus.D4394 172is better suited
23、to small stress changes. The ratio between the secant modulus and the tangent modulus can be used as a meansof 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 or underground chamber are flattened and smoothed.4
24、.2 Amortar pad and rigid metal plate are installed against each face and a hydraulic loading system is placed between the rigidplates.4.3 If deflection is to be measured within the rock mass, extensometer instruments shall be installed in the rock in accordancewith Practice D4403.4.4 The two faces a
25、re loaded and unloaded incrementally and the deformations of the rock mass at the surfaces and, if desired,within the rock, are measured after each load and unload increment. The modulus of deformation is then calculated.(Secant,Tangent and/or Recovery) is then calculated on those segments of the da
26、ta plot pertinent to the data acquisition program.5. Significance and Use5.1 Results of this type of test method are used to predict displacements in rock mass caused by loads from a structure or fromunderground construction. It is one of several tests that should be performed. The resulting in situ
27、 elastic modulus is commonlyless than the elastic modulus determined in the laboratory.5.2 The modulus is determined using an elastic solution for a uniformly distributed load (uniform stress) over a circular areaacting on a semi-infinite elastic medium that produces a constant normal displacement o
28、f the loaded surface area of the medium.5.3 This test method is normally performed at ambient temperature, but equipment can be modified or substituted for operationsat other temperatures.NOTE 1The quality of the result produced by this standard is dependent on the competence of the personnel perfor
29、ming it, and the suitability of theequipment and facilities used. Agencies that meet the criteria of Practice D3740 are generally considered capable of competent and objectivetesting/sampling/inspection/etc. Users of this standard are cautioned that compliance with Practice D3740 does not in itself
30、assure reliable results. Reliableresults depend on many factors; Practice D3740 provides a means of evaluating some of those factors.6. Interferences6.1 An inflexible plate used to load the rock face is difficult to construct. However, if the plate is constructed as rigid aspracticable, the rock fac
31、e is smoothed, 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 not homogeneous, as assumed in theory. Rock will respond to the load accordingto its local deformational characteristics. Therefore, deflection measurements at d
32、iscrete points on the rock surface tend to beheavily influenced by the deformational characteristics of the rock mass at that location and may give results that areunrepresentative of the rock mass. The use of the average plate deflection will mitigate this problem.6.3 Measurement of the deflection
33、within the rock mass can utilize a finite gauge length to reflect the average rock massdeformation properties between the measuring points. This approach entails three drawbacks, however. First, the rock mass istested at very low stress levels unless the measurement points are very close to the rock
34、 surface, and because of this, the sameproblems as with surface measurements occur. Tests at low stress levels may give unrealistically low modulus values becausemicrofractures, joints, and other discontinuities in the rock are open. Secondly, the disturbance caused by implanting the deflectiontrans
35、ducer in the rock mass is difficult to evaluate. The techniques in this test method are designed to produce minimal disturbance.Thirdly, in rocks with very high modulus, the accuracy of the instruments may be insufficient to provide reliable results.6.4 Time-rate of loading has negligible influence
36、on the modulus.6.5 Calculations 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 from laboratory testing.FIG. 2 Relationship Between Tangent, Secant and Recovery Moduli for a Single Cycle of Loading and Unlo
37、adingD4394 1737. Apparatus7.1 Equipment necessary for accomplishing this test method includes items for: preparing the test site, drilling and logging theinstrumentation holes, measuring the rock deformation, applying and restraining test loads, recording test data, and transportingvarious component
38、s to the test site.7.2 Test Site Preparation EquipmentThis shall include an assortment of excavation tools, such as drills drills, drill bits, andchipping hammers. Blasting shall not be allowed during a preparation of the test site. The drill for the instrumentation holes shall,if practicable, have
39、the capability of retrieving cores from depths of about 30 ft (10 m).7.3 Borehole Viewing DeviceSome type of device is desirable for observation of the instrumentation holes to compare andverify geologic features observed in the core if core recovery is poor or if it is not feasible to retrieve orie
40、nted cores.7.4 Deformation Measuring InstrumentsInstruments for measuring deformations shall include a reliable multiple-positionborehole extensometer (MPBX) for each instrumentation hole and a tunnel diameter gauge. For surface measurements, dial gagesor linear variable differential transformers (L
41、VDTs) are generally used. An accuracy of 60.0001 in. (0.0025 mm), including theerror of the readout equipment, and a sensitivity of at least 0.00005 in. (0.0013 mm) is recommended. Errors in excess of 0.0004in. (0.01 mm) can invalidate test results when the modulus of rock mass exceeds 5 106 psi (3.
42、5 10 4 MPa).7.5 Loading EquipmentThe loading equipment includes the device for applying the load and the reaction members (usuallythick-walled aluminum or steel pipes) which transmit the load. load of sufficient capacity for the intended test program. Hydraulicrams or flatjacks are usually used to a
43、pply the load hydraulically with sufficient capability and volume to apply and maintaindesired pressures to within 3 %. If flatjacks are used they should have sufficient range to allow for deflection of the rock and shouldbe constructed so that the two main plates move apart in a parallel manner ove
44、r the usable portion of the loading range.Asphericalbearing of suitable capacity should be coupled to one of the bearing plates.7.6 Load Cells and TransducersA load cell is recommended to measure the load on the bearing plate. An accuracy of around61000 lbf (64.4 kN), including errors introduced by
45、the readout system, and a sensitivity of 500 lbf (2.2 kN) are recommended.Alternatively, a pressure gauge or transducer may be used to monitor hydraulic pressure for calculation of load, provided the devicecan measure the load to the same specifications as the load cell. An accuracy of 620 psi (60.1
46、4 MPa), including error introducedby readout equipment, and a sensitivity of 10 psi (0.069 MPa). If a hydraulic ram is used, the effects of ram friction shall bedetermined. If flatjacks are used, care shall be taken that the jacks do not operate at the upper end of their range.7.7 Bearing PadsThe be
47、aring pads shall have a modulus of elasticity of around 4 106 psi (3 104MPa) and shall be capableof conforming to the rock surface and bearing plate. High-early strength grout or molten sulfur bearing pads are recommended.7.8 Bearing PlatesThe bearing plates shall approximate a rigid die as closely
48、as practical.Abearing plate that has been foundsatisfactory is shown on Fig. 3. Although the exact design and materials may differ, the stiffness of the bearing plate shall be theminimum stiffness necessary to not produce measurable deflection of the plate under maximum load.8. Safety Hazards8.1 Per
49、sonnel involved in performing the test shall be formally prequalified under the quality assurance procedures listed inEnforce safety by applicable safety standards. Annex A1.8.2 Verify the compliance of equipment and apparatus with the performance specifications in Section Pressure lines 7. Ifrequirements are not stated, the manufacturers specifications for the equipment may be appropriate as a guide, however, careshould be taken for sufficient performance. Performance verification is generally done by calibrating the equipment andmeasurement
