ASTM D4553 - 08 Standard Test Method for Determining In Situ Creep Characteristics of Rock (Withdrawn 2017).pdf

1、Designation: D4553 08Standard Test Method forDetermining In Situ Creep Characteristics of Rock1This standard is issued under the fixed designation D4553; the number immediately following the designation indicates the year oforiginal adoption or, in the case of revision, the year of last revision. A

2、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 documentation for determining in situcreep characteristics

3、 of a rock mass using a rigid platesubjected to controlled loading.1.2 This test method is designed to be conducted in anunderground opening; however, with suitable modifications,this test could be conducted at the surface.1.3 The test is usually conducted parallel or perpendicular tothe anticipated

4、 axis of thrust, as dictated by the design load orother orientations, based upon the application.1.4 Flexible plate apparatus can be used if the anticipatedcreep displacement is within the tolerance of the travel of theflat jacks.1.5 The values stated in inch-pound units are to be regardedas standar

5、d. The values given in parentheses are mathematicalconversions to SI units that are provided for information onlyand are not considered standard.1.6 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 stand

6、ard to establish appro-priate safety and health practices and determine the applica-bility of regulatory limitations prior to use. For specificprecaution statements, see Section 8.2. Referenced Documents2.1 ASTM Standards:2D653 Terminology Relating to Soil, Rock, and ContainedFluidsD3740 Practice fo

7、r Minimum Requirements for AgenciesEngaged in Testing and/or Inspection of Soil and Rock asUsed in Engineering Design and ConstructionD4394 Test Method for Determining In Situ Modulus ofDeformation of Rock Mass Using Rigid Plate LoadingMethodD4403 Practice for Extensometers Used in Rock3. Terminolog

8、y3.1 DefinitionsSee Terminology D653 for general defini-tions.3.2 Definitions of Terms Specific to This Standard:3.2.1 creepa time-dependent displacement of a platepushed into the surface of the rock by a constant normal load.It is not directly related with laboratory creep data because ofthe nonuni

9、formity of stress within the rock mass underneaththe plate.3.2.2 displacementmovement of the rigid plate, grout pad,or rock in response to and in the same direction as the appliedload.3.2.3 loadtotal force acting on the rock face.3.2.4 rigid plateplate with a deflection of less than 0.0005in. (0.012

10、5 mm) from the center to the edge of the plate whenmaximum load is applied.4. Summary of Test Method4.1 Areas on two opposing faces of a test opening areflattened, smoothed, and made parallel.4.2 A grout pad and rigid metal plate are installed againsteach face and a hydraulic loading system is place

11、d between therigid plates.4.3 The two faces are rapidly loaded to the desired creepload, without shock, the load maintained, and the displacementof the plate measured as a function of time.5. Significance and Use5.1 Results of this test method are used to predict time-dependent deformation character

12、istics of a rock mass resultingfrom loading. It is a test that may be required depending onrock type or anticipated loads, or both.5.2 This test method may be useful in structural designanalysis where loading is applied over an extensive period.5.3 This test method is normally performed at ambientte

13、mperature, but equipment can be modified or substituted foroperations at other temperatures.1This test method is under the jurisdiction ofASTM Committee D18 on Soil andRock and is the direct responsibility of Subcommittee D18.12 on Rock Mechanics.Current edition approved July 1, 2008. Published July

14、 2008. Originally approvedin 1985. Last previous edition approved in 2006 as D4553 02 (2006). DOI:10.1520/D4553-08.2For 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 t

15、he standards Document Summary page onthe ASTM website.*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 StatesNOTICE: This standard has either been superseded and replaced by a n

16、ew version or withdrawn.Contact ASTM International (www.astm.org) for the latest information15.4 Results of this test method may be useful in verifyinglaboratory creep data and structural mathematical modelinganalyses.5.5 Creep characteristics are determined under a nonuni-form state of stress.5.6 I

17、f during a field investigation, time-dependent charac-teristics are detected, then an in situ creep test shall beperformed.NOTE 1The quality of the result produced by this standard isdependent on the competence of the personnel performing it, and thesuitability of the equipment and facilities used.

18、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 itself assurereliable results. Reliable results depend on many factors; Pra

19、ctice D3740provides a means of evaluating some of those factors.6. Interferences6.1 A completely inflexible plate used to load the rock faceis difficult to construct. However, if the plate is constructed asrigid as feasible, the rock face is smoothed, and a thin,high-modulus material is used for the

20、 pad, the error in themeasured displacements will be minimal.6.2 The rock under the loaded area is generally nothomogeneous, as assumed in theory. The rock will respond tothe load according to its local deformational characteristics andorientation of discontinuities. The use of the average platedisp

21、lacement will mitigate this problem. If this creep test isperformed immediately after a plate loading test, the results ofthe creep test will be different than if it had been performed onvirgin rock.7. Apparatus7.1 Surface Preparation Equipment Test-site preparationequipment should include an assort

22、ment of excavation tools,such as drills and chipping hammers. Blasting shall not beallowed during final preparation of the test site.7.2 Instrumentation:7.2.1 Displacement Measuring Equipment For displace-ment measurements, dial gauges or linear variable differentialtransformers (LVDTs) are generall

23、y used. A sensitivity of atleast 60.0001 in. (60.0025 mm), including the error of thereadout equipment, and an accuracy of at least 0.0005 in.(0.0125 mm) are required. Errors in excess of 0.0004 in. (0.01mm) can invalidate test results when the modulus of rock massexceeds 5 106psi (3.5 104MPa).7.2.2

24、 Load CellA load cell is recommended to measurethe load on the bearing plate. An accuracy of 61000 lbf (4.4kN) or 65 % of maximum test load, including errors intro-duced by the readout system, and a sensitivity of at least 500lbf (2.2 kN) are reasonable. Long-term stability of the instru-mentation s

25、ystem shall be verified throughout the test.7.3 Loading Equipment:7.3.1 Hydraulic Ram or Flat JacksThis equipment, ca-pable of applying and maintaining desired pressures to within63 %, is usually used to apply the load. A spherical bearing ofsuitable capacity shall be coupled to one of the bearing p

26、lates.If a hydraulic ram is used, the load shall be corrected toaccount for the effects of ram friction. If flat jacks are used, thejacks shall not be expanded beyond a thickness equal to 3 % ofthe diameter of a metal jack.7.3.2 The loading equipment includes a device for applyingthe load and the re

27、action members, usually thick-walledaluminum or steel pipes, to transmit the load.7.3.3 Load Maintaining EquipmentEquipment such as aservo-control system or air over hydraulic oil is required.7.3.4 Bearing PadsThe bearing pads shall have a modulusof elasticity of at least 4 106psi (3 104MPa) (30 GPa

28、) andshall be capable of conforming to the rock surface and bearingplate. High early strength grout or molten sulfur bearing padsare recommended.7.3.5 Bearing PlatesThe bearing plates shall approximatea rigid die as closely as practical. A bearing plate that has beenfound satisfactory is shown in Fi

29、g. 1.Although the exact designand materials may differ, the stiffness of the bearing plate shallbe at least the minimum stiffness necessary to produce nomeasurable deflection of the plate under maximum load.8. Precautions8.1 All equipment and apparatus shall comply with theperformance specifications

30、 in Section 7 and apparatus shall beverified. If no requirements are stated in Section 7, themanufacturers specifications for the equipment may be appro-priate as a guide to assure acceptable performance. Perfor-mance verification is generally done by calibrating the equip-ment and measurement syste

31、m (see Fig. 2).8.2 Enforce safety by applicable safety standards. Pressurelines must be bled of air to preclude violent failure of thepressure system.9. In Situ Conditions9.1 Areas that are geologically representative of the massshall be selected. The plates shall be contained in the samegeologic me

32、mber. The testing program shall be designed sothat effects of local geology can be clearly distinguished andthe impact of excavation minimized.9.2 The size of the bearing plate will be determined by thelocal geology, pressures to be applied, and the size of theopening in which the test is to be perf

33、ormed. These parametersshall be considered prior to excavation of the opening. Opti-mum opening dimensions are approximately six times the platediameter. Recommended plate diameter is commonly 1 1/2 to3 1/2 ft (0.5 to 1 m). Other plate sizes may be used dependingupon site specifics.9.3 The effects o

34、f anisotropy shall be investigated byappropriately oriented tests; for example, parallel and perpen-dicular to the long axes of columns in a basalt flow.9.4 Tests shall be performed at a site not affected bystructural changes resulting from excavations of the opening.The zone of rock that contribute

35、s to the measured displacementduring loading depends on the diameter of the plate and theapplied load. Larger plates and higher loads measure theresponse of rock farther away from the test opening. Thus, ifthe rock around the opening is damaged by the excavationprocess and the creep properties of th

36、e damaged zone are theD4553 082primary objective of the test program, small-diameter platetests on typically excavated surfaces are adequate.9.5 Site conditions may dictate that site preparation and padconstruction be performed immediately after excavation.10. Procedure10.1 A schematic of an optimum

37、 test setup is shown in Fig.3. A properly located platform (not shown) allows for align-ment of all test components.10.2 Conduct the test across a “diameter” or chord of theopening with the two test surfaces nearly parallel and in planesoriented perpendicular to the thrust of the loading assembly.10

38、.3 Surface Preparation:10.3.1 MethodPrepare the surface by a method that causesminimal damage to the finished rock surface. In the initialpreparation of the finished test surface, many short drill holesmay be required to remove unsound rock. Any residual rockbetween the drill holes may be removed by

39、 burnishing ormoving the bit back and forth until a smooth face is achieved.Alternatively, in hard, competent rock, controlled blasting withvery small charges may be required to remove the unwantedmaterials. In weaker materials, coarse grinding or cuttingdevices may be used.10.3.2 SizeThe prepared r

40、ock surface shall extend at leastone-half the diameter of the bearing plate beyond the edge ofthe plate.10.3.3 Rock QualityTo the extent possible, prepare thebearing surface in sound rock. Remove loose and broken rockfrom the excavation. Deeper breaks may be detected by a dullhollow sound when the r

41、ock surface is struck with a hammer;remove such material.10.3.4 SmoothnessThe prepared rock face shall be assmooth as practicable. In no case shall the deviation from aplane between the highest and lowest points exceed 1 in. (25mm).10.3.5 CleaningAfter the surface has been prepared, scruband rinse i

42、t with clean water to remove any loose particles ordirt caused by the smoothing operation.10.4 Bearing Pad ConstructionConstruct the bearing pad,with the bearing plate in position, by pouring the pad materialbetween the rock surface and the plate. Contain the padFIG. 1 Rigid Bearing Plate for 12 in.

43、 Diameter TestD4553 083material by suitable form work around the edges of the plate.The only exception to this method is for near vertical testswhere grout pads are used. In this case, the lower bearing platemay be placed directly upon the pad prior to curing. In allcases, exercise care to avoid air

44、 pockets or other cavities withinthe pad. The thickness of the pad shall be no more than 15 %of the plate diameter at any point. The dimensional require-ments are shown in Fig. 4.10.5 Displacement Measuring Points Measure the dis-placement of the bearing plate in at least three locations equallyspac

45、ed around the plate. Support the displacement transducersso that only the displacement of the plate is measured.Generally, this means mounting the transducers from supportslocated outside the zone of influence of the test. In no case shallthe transducers be mounted on the loading apparatus. Crossope

46、ning measurement points and equipment such as describedin Practice D4403 may be installed if desired.10.6 Pretest CheckAfter the loading and restraining com-ponents are installed, make a final check of all mechanical,hydraulic, and electronic components after the grout pads areplaced and again before the load is applied.10.7 Pressurization (Loading):10.7.1 Zero all measuring equipment.Project _ Test No. _Feature _ Rock type _Test location _ Plate diameter _Orientation _ Tested by _Sustain Load _EquipmentdescriptionSerialno.Date ofnext calibration_ _ _ _ _ _ _ _ _