1、Designation: D4395 08D4395 17Standard Test Method forDetermining In Situ Modulus of Deformation of Rock MassUsing Flexible Plate Loading Method1This standard is issued under the fixed designation D4395; the number immediately following the designation indicates the year oforiginal adoption or, in th
2、e case 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 reductio
3、n for determining in situ modulus ofdeformation of a rock mass using the flexible 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 co
4、nducted 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 not covered by this standard can be perfo
5、rmed but are to be reported in another standard.1.6 All observed and calculated values shall conform to the guidelines for significant digits and rounding established in PracticeD6026.1.6.1 The method used to specifiyspecify how data are collected, calculated, or recorded in this standard is not dir
6、ectly relatedto the accuracy to which the data can be applied in design or other uses, 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 regarded as standard. standard, except as noted below. The values given inpa
7、rentheses are mathematical conversions to SI units that are provided for information only and are not considered standard.Reporting of test results in units other than SI shall not be regarded as nonconformance with this test method.1.8 The references appended to this standard contain further inform
8、ation 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 the user of this standard to establish appropriate safety and health practices and determine the applicability of regulatorylimitations prio
9、r to use. For specific precaution statements, see Section 8.1.10 This international standard was developed in accordance with internationally recognized principles on standardizationestablished in the Decision on Principles for the Development of International Standards, Guides and Recommendations i
10、ssuedby the World Trade Organization Technical Barriers to Trade (TBT) Committee.2. Referenced Documents2.1 ASTM Standards:2D653 Terminology Relating to Soil, Rock, and Contained FluidsD2113 Practice for Rock Core Drilling and Sampling of Rock for Site ExplorationD3740 Practice for Minimum Requireme
11、nts for Agencies Engaged in Testing and/or Inspection of Soil and Rock as Used inEngineering Design and ConstructionD4394 Test Method for Determining In Situ Modulus of Deformation of Rock Mass Using Rigid Plate Loading MethodD4403 Practice for Extensometers Used in RockD4879 Guide for Geotechnical
12、Mapping of Large Underground Openings in Rock (Withdrawn 2017)31 This test 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 July 2008August 20
13、17. Originally approved in 1984. Last previous edition approved in 20042008 asD4395 04.D4395 08. DOI: 10.1520/D4395-08.10.1520/D4395-17.2 For referencedASTM standards, visit theASTM website, www.astm.org, or contactASTM Customer Service at serviceastm.org. For Annual Book of ASTM Standardsvolume inf
14、ormation, refer to the standards Document Summary page on the ASTM website.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
15、made to the previous version. Becauseit may not be technically possible 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.*
16、A Summary of Changes section appears at the end of this standardCopyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States1D5079 Practices for Preserving and Transporting Rock Core Samples (Withdrawn 2017)3D5434 Guide for Field Logging of Subsur
17、face Explorations of Soil and RockD6026 Practice for Using Significant Digits in Geotechnical DataD6032 Test Method for Determining Rock Quality Designation (RQD) of Rock Core3. Terminology3.1 For terminology used in this test method, refer to Terminology D653.Definitions:3.1.1 For terminology used
18、in this test method, refer to Terminology D653.3.2 Definitions of Terms Specific to This Standard:3.2.1 deflectiondeflection, nmovement of the plate, mortar pad, or rock in response to and in the same direction as theapplied load.3.2.2 flexible plateplate, ntheoretically, a plate having no stiffness
19、.3.2.3 loadtotal force acting on the rock face.3.2.3 peak-to-peak modulus of deformationdeformation, nthe slope of stress - strain curve line connecting the peaks of thecurves obtained from successive pressure cycles (see Fig. 1).3.2.4 recovery modulus of deformationdeformation, nthe tangent modulus
20、 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 indicates the materials capacity of hysteresis or energy dissipation capabilities (see Fig.
21、2).3.2.5 secant modulus of deformationdeformation, nthe slope of the stress - strain curve between zero stress and anyspecified stress. This modulus should be used for complete load steps from zero to the desired load (see Fig. 2).3.2.6 tangent modulus of deformationdeformation, nthe slope of the st
22、ress - strain curve obtained over the segment of theloading curve judged as the most representative of elastic response by the investigator. It neglects the end effects of the curve andFIG. 1 Rock Surface Deformation as a Function of Bearing Pressure and Increasing Loading Cycles PlotArrows show up
23、and downdirection of loading cycles line shows Peak to Peak Modulus.D4395 172is better suited 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
24、two opposing parallel faces sides of a test adit are or underground chamber are made parallel and then flattenedand smoothed.4.2 A hydraulic loading system consisting of flatjacks, flat jacks, reaction members, and associated hardware is constructedbetween the two faces and a mortar pad is placed on
25、 each face.4.3 If deflection is to be measured within the rock mass, install extensometer instruments in the rock in accordance with PracticeD4403.4.4 The two faces are loaded and unloaded incrementally and the deformations of the rock mass at the surfaces and, if desired,within the rock, are measur
26、ed 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 data plot pertinent to the data acquisition program.5. Significance and Use5.1 Results of this type of test method are used to predict d
27、isplacements 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 elastic modulus is commonlyless than the elastic modulus determined in the laboratory.5.2 The modulus is determined using an elastic
28、solution for a uniformly distributed load (uniform stress) over a circular areaacting on a semi-infinite elastic 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
29、produced by this standard is dependent on the competence of the personnel performing 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 th
30、is standard are cautioned that compliance with Practice D3740 does not in itself assure reliable results.Reliable results depend on many factors; Practice D3740 provides a means of evaluating some of those factors.6. Interferences6.1 The rock under the loaded area is generally not homogeneous, as as
31、sumed in theory. Rock will respond to the load accordingto its local deformational characteristics. Therefore, deflection measurements at discrete 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
32、areunrepresentative of the rock mass. The use of the average plate deflection will mitigate this problem.6.2 Measurement of the deflection within the rock mass can utilize a finite gauge length to reflect the average rock massdeformation properties between the measuring points. This approach entails
33、 three drawbacks, however. First, the rock mass istested at very low stress levels unless the measurement points are very close to the rock surface and because of this, the sameproblems as with surface measurements occur. Tests at low stress levels may give unrealistic modulus values becausemicrofra
34、ctures, joints, and other discontinuities in the rock are open. Secondly, the disturbance caused by implanting the deflectiontransducer 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,
35、the accuracy of the instruments may be insufficient to provide reliable results.6.3 Time-rate of loading has negligible influence on the modulus.6.4 Calculations neglect the stress history of the rock.6.5 This test method is insensitive to Poissons ratio, which must be assumed or obtained from labor
36、atory testing.FIG. 2 Relationship Between Tangent, Secant, and Recovery Moduli for a Single Loading and Unloading CycleD4395 1737. Apparatus7.1 Equipment necessary for accomplishing this test method includes items for: preparing the test site, drilling and logging theinstrumentation holes, measuring
37、 the rock deformation, applying and restraining test loads, recording test data, and transportingvarious components to the test site.7.2 Test Site Preparation EquipmentThis should include an assortment of excavation tools, such as drills drills, drill bits andchipping hammers. Blasting should not be
38、 allowed during final preparation of the test site. The drill for the instrumentation holesshould, if possible, have the capability of retrieving cores from depths of at least 30 ft (10 m).7.3 Borehole Viewing DeviceSome type of device is desirable for examination of the instrumentation holes to com
39、pare andverify geologic features observed in the core if core recovery is poor or if it is not feasible to retrieve oriented cores.7.4 Deformation Measuring InstrumentsInstruments for measuring deformations should include a reliable multiple positionborehole extensometer (MPBX) for each instrumentat
40、ion hole and a tunnel diameter gauge. For surface measurements, dial gages,or linear variable differential transformers (LVDTs) are generally used.An accuracy of at least6 0.0001 in. (0.0025 mm), includingthe error of the readout equipment, and a sensitivity of at least 0.00005 in. (0.0013 mm) is re
41、commended. Errors in excess of0.0004 in. (0.01 mm) can invalidate test results when the modulus of rock mass exceeds 5 106 psi (3.5 104 MPa).7.5 Loading EquipmentThe loading equipment includes the device for applying the load and the reaction members (usuallythick-walled aluminum or steel pipes) whi
42、ch transmit the load. Flatjacks load of sufficient capacity for the intended test program.Flat jacks at each rock face should be used to apply the load and should have sufficient range to allow for deflection of the rockand maintain pressure to within 3 %. They should be constructed so that the two
43、main plates move apart in a parallel manner overthe usable portion of the range. A spherical bearing of suitable capacity should be incorporated in the reaction members.7.6 Load Measuring InstrumentsA pressure gauge/transducer or load cell should be used to measure the pressure in theflatjacks. flat
44、 jacks. The pressure gauge or transducer should have an accuracy of at least 620 psi (0.14 MPa), including errorintroduced by readout equipment, and a sensitivity of at least 10 psi (0.069 MPa). The load cell should have an accuracy of at least61000 lbf (4.4 kN) including errors introduced by the re
45、adout system, and a sensitivity of at least 500 lbf (2.22 kN) isrecommended.7.7 Bearing PadsThe bearing pad material shall have a modulus no greater than the modulus of the rock being tested, asdetermined from an intact test sample. Generally, a neat cement grout is satisfactory if the curing time d
46、oes not exceed several days.Fly ash or other suitable materials may be added to reduce the stiffness, if necessary.8. Safety Precautions8.1 All personnel involved in performing the test should be formally pre-qualified in accordance with the quality assuranceprocedures of Enforce safety by applicabl
47、e safety standards.Annex A1.8.2 Verify the compliance of all equipment and apparatus with the performance specifications in Section Pressure lines 7. If norequirements are stated, the manufacturers specifications for the equipment may be appropriate as a guide, but care must be takenfor sufficient p
48、erformance. Performance verification is generally done by calibrating the equipment and measurement system.Accomplish calibration and documentation in accordance with must be bled of air to preclude violent failure of the pressuresystem.Annex A1.8.3 Enforce safety by applicable safety standards. Pre
49、ssure lines must be bled of air to preclude violent failure of the pressuresystem. Total deformation should not exceed the expansion capabilities of the flatjacks; flat jacks; normally this is approximately3 % of the diameter of a metal flatjack.flat jack.9. In Situ ConditionsNOTE 2The guidelines presented in this section are the domain of the agency or organization requesting the testing and are intended to facilitatedefinition of the scope and development of site-specific requirements for the testing program as a whole.9.1 Test each structurally
