1、Designation: D 6773 08Standard Test Method forBulk Solids Using Schulze Ring Shear Tester1This standard is issued under the fixed designation D 6773; the number immediately following the designation indicates the year oforiginal adoption or, in the case of revision, the year of last revision. A numb
2、er 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 apparatus and proceduresfor measuring the unconfined yield strength of bulk solidsduring both continuous flow
3、and after storage at rest. Inaddition, measurements of internal friction, bulk density, andwall friction on various wall surfaces are included.1.2 The most common use of this information is in thedesign of storage bins and hoppers to prevent flow stoppagesdue to arching and ratholing, including the
4、slope and smooth-ness of hopper walls to provide mass flow. Parameters forstructural design of such equipment may also be derived fromthis data. Another application is the measurement of theflowability of bulk solids, for example, for comparison ofdifferent products or optimization.1.3 All observed
5、and calculated values shall conform to theguidelines for significant digits and rounding established inPractice D 6026.1.3.1 The procedures used to specify how data are collected/recorded or calculated in this standard are regarded as theindustry standard. In addition, they are representative of the
6、significant digits that generally should be retained. The proce-dures used do not consider material variation, purpose forobtaining the data, special purpose studies, or any consider-ations for the users objectives: and it is common practice toincrease or reduce significant digits of reported data t
7、o becommensurate with these considerations. It is beyond the scopeof this standard to consider significant digits used in analysismethods for engineering design.1.4 The values stated in SI units are to be regarded asstandard. No other units of measurement are included in thisstandard.1.5 This standa
8、rd does not purport to address all of thesafety concerns, if any, associated with its use. It is theresponsibility of the user of this standard to establish appro-priate safety and health practices and determine the applica-bility of regulatory limitations prior to use.2. Referenced Documents2.1 AST
9、M Standards:2D 653 Terminology Relating to Soil, Rock, and ContainedFluidsD 3740 Practice for Minimum Requirements for AgenciesEngaged in Testing and/or Inspection of Soil and Rock asUsed in Engineering Design and ConstructionD 6026 Practice for Using Significant Digits in Geotechni-cal DataD 6128 T
10、est Method for Shear Testing of Bulk Solids Usingthe Jenike Shear Cell3. Terminology3.1 For common definitions of terms in this standard, referto Terminology D 653.3.2 Definitions of Terms Specific to This Standard:3.2.1 adhesion test, na static wall friction test with timeconsolidation.3.2.2 angle
11、of internal friction, wi, nthe angle between theaxis of normal stress (abscissa) and the tangent to the yieldlocus.3.2.3 angle of wall friction, f8, nthe arctan of the ratio ofthe wall shear stress to the wall normal stress.3.2.4 bin, na container or vessel for holding a bulk solid,frequently consis
12、ting of a vertical cylinder with a converginghopper. Sometimes referred to as silo, bunker or elevator.3.2.5 bulk density, rb, nthe mass of a quantity of a bulksolid divided by its total volume.3.2.6 bulk solid, nan assembly of solid particles handledin sufficient quantities that its characteristics
13、 can be describedby the properties of the mass of particles rather than thecharacteristics of each individual particle. It may also bereferred to as a granular material, particulate solid, or powder.Examples are sugar, flour, and ore.3.2.7 bunker, nsynonym for bin, but sometimes under-stood as being
14、 a bin without any or only a small vertical partat the top of the hopper.1This test method is under the jurisdiction ofASTM Committee D18 on Soil andRock and is the direct responsibility of Subcommittee D18.24 on Characterizationand Handling of Powders and Bulk Solids.Current edition approved Oct. 1
15、, 2008. Published November 2008. Originallyapproved in 2002. Last previous edition approved in 2002 as D 6773 02.2For 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
16、 standards Document Summary page onthe ASTM website.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.3.2.8 consolidation, nthe process of decreasing the poros-ity of a
17、bulk solid, which usually results in increasing itsunconfined yield strength.3.2.9 critical state, na state of stress in which the bulkdensity of a bulk solid and the shear stress in the shear zoneremain constant during shear under constant normal stress.3.2.10 effective angle of friction, d, nthe i
18、nclination of theeffective yield locus (EYL).3.2.11 effective yield locus (EYL), nstraight line passingthrough the origin of the s, t-plane and tangential to the steadystate Mohr circle, corresponding to steady state flow conditionsof a bulk solid of given bulk density.3.2.12 elevator, nsynonym for
19、bin. Commonly used inthe grain industry.3.2.13 failure (of a bulk solid), nplastic deformation of anoverconsolidated bulk solid subject to shear, causing dilationand a decrease in strength.3.2.14 flow, steady state, ncontinuous plastic deformationof a bulk solid at critical state.3.2.15 flow functio
20、n, FF, nthe plot of unconfined yieldstrength versus major consolidation stress for one specific bulksolid.3.2.16 granular material, nsynonym for bulk solid.3.2.17 hopper, nthe converging portion of a bin.3.2.18 major consolidation stress, s1, nthe major princi-pal stress given by the Mohr stress cir
21、cle of steady state flow.This Mohr stress circle is tangential to the effective yield locus.3.2.19 Mohr stress circle, nthe graphical representation ofa state of stress in coordinates of normal and shear stress, thatis, in the s, t-plane.3.2.20 normal stress, s, nthe stress acting normally to thecon
22、sidered plane.3.2.21 particulate solid, nsynonym for bulk solid.3.2.22 powder, nsynonym for bulk solid, particularlywhen the particles of the bulk solid are fine.3.2.23 silo, nsynonym for bin.3.2.24 shear test, nan experiment to determine the flowproperties of a bulk solid by applying different stat
23、es of stressand strain to it.3.2.25 shear tester, nan apparatus for performing sheartests.3.2.26 time angle of internal friction, wt, ninclination ofthe time yield locus of the tangency point with the Mohr stresscircle passing through the origin.3.2.27 time yield locus, nthe yield locus of a bulk so
24、lidwhich has remained at rest for a certain time under a givennormal stress for a certain time.3.2.28 unconfined yield strength, fc, nthe major principalstress of the Mohr stress circle being tangential to the yieldlocus with the minor principal stress being zero.3.2.29 wall normal stress, sw, nthe
25、normal stress presentat a confining wall.3.2.30 wall shear stress, tw, nthe shear stress present at aconfining wall.3.2.31 wall yield locus, na plot of the wall shear stressversus wall normal stress. The angle of wall friction is obtainedfrom the wall yield locus as the arctan of the ratio of the wa
26、llshear stress to wall normal stress.3.2.32 yield locus, nplot of shear stress versus normalstress at failure. The yield locus (YL) is sometimes called theinstantaneous yield locus to differentiate it from the time yieldlocus.4. Summary of Test Method4.1 A representative specimen of bulk solid is pl
27、aced in ashear cell of specific dimensions.4.2 When running an instantaneous or time shear test, anormal load is applied to the cover, and the specimen ispresheared until a steady state shear value has been reached.The shear stress is then immediately reduced to zero.4.3 An instantaneous test is run
28、 by shearing the specimenunder a reduced normal load until the shear force goes througha maximum value and then begins to decrease.4.4 A time shear test is run similarly to an instantaneousshear test, except that the specimen is placed in a consolidationbench for the specified time between the presh
29、ear and shearsteps.4.5 A wall friction test is run by sliding the specimen overa coupon of wall material and measuring the frictional resis-tance as a function of normal, compressive load.4.6 A wall friction time test involves sliding the specimenover the coupon of wall material, stopping and leavin
30、g the loadon the specimen for a predetermined period, and then sliding itagain to see if the shearing force has changed.5. Significance and Use5.1 Reliable, controlled flow of bulk solids from bins andhoppers is essential in almost every industrial facility. Unfor-tunately, flow stoppages due to arc
31、hing and ratholing arecommon. Additional problems include uncontrolled flow(flooding) of powders, segregation of particle mixtures, useablecapacity which is significantly less than design capacity, cakingand spoilage of bulk solids in stagnant zones, and structuralfailures.5.2 By measuring the flow
32、properties of bulk solids, anddesigning bins and hoppers based on these flow properties,most flow problems can be prevented or eliminated (1).35.3 For bulk solids with a significant percentage of particles(typically, one third or more) finer than about 6 mm (14 in.), theunconfined yield strength is
33、governed by the fines (6 mmfraction). For such bulk solids, strength and wall friction testsmay be performed on the fine fraction only.5.4 This test method covers operation of the manually-controlled Schulze Ring Shear Tester.An automated version ofthis tester is also available. Its method of testin
34、g bulk solids issimilar in principle to that described in this test method.NOTE 1The quality of the result produced by this standard isdependent on the competence of personnel performing it, and thesuitability of the equipment and facilities used. Agencies that meet thecriteria of Practice D 3740 ar
35、e generally considered capable of competentand objective testing/sampling/inspection/etc. Users of this standard arecautioned that compliance with Practice D 3740 does not in itself assurereliable results. Reliable results depend on many factors; Practice D 37403The boldface numbers in parentheses r
36、efer to the list of references at the end ofthis standard.D6773082provides a means of evaluating some of those factors. Practice D 3740 wasdeveloped for agencies engaged in the testing or inspection (or both) ofsoil and rock. As such it is not totally applicable to agencies performingthis standard.
37、However, users of this standard should recognize that theframework of Practice D 3740 is appropriate for evaluating the quality ofan agency performing this standard. Currently there is no known quali-fying national authority that inspects agencies that perform this standard.6. Apparatus6.1 The Schul
38、ze Ring Shear Tester (Figs. 1-6) is composedof a base 1 and a casing 2. The casing 2 contains the drivingand measuring units and carries the working table 38.6.2 The driving axle 5 (with detachable plastic cap 6) causesthe shear cell 4 to rotate. The driver pins at the underside of theshear cell mus
39、t set in the toothed wheel at the driving axle 5 toenable a close connection between shear cell and driving axle.The driving axle is driven by an electric motor and can rotateto the right or to the left. In order to shear the bulk solidspecimen, the driving axle 5 along with the shear cell 4 rotatec
40、lockwise (as seen from the top). The electric motor iscontrolled from the front panel 35 at the front side of casing 2(Fig. 3). The motor and drive system cause the shear cell torotate at a speed adjustable between 0.007 and 0.13 rad/min.6.3 The shear cell lid 7 as well as the bottom of the shearcel
41、l 4 has bent bars made of stainless steel (Fig. 4) to preventslipping of the bulk solid at the lid or the bottom of the shearcell.NOTE 2The standard cell has 20 bars, each of which is 4 mm tall(hMit= 4 mm, Fig. 8).6.4 The crossbeam 8 sits on the lid 7 and is fixed with twoknurled screws 9.The crossb
42、eam 8 has several functions: In thecenter of the crossbeam 8 is a fixed axis 10 with a hook toappend the hanger 11 (in Figs. 3 and 4 only the handle of thehanger standing out from the driving axle can be seen). Rollersat the ends of the crossbeam and the removable guide rollers 12prevent movement of
43、 lid 7 from the centered position.6.5 A hook 14 at the upper end of the axis 10 of thecrossbeam 8 is fastened to the balance arm 15. This arm alongwith counterbalance 29 (Fig. 6) serves to compensate for themasses of lid 7, crossbeam 8, hanger 11, and tie rods 13. Thecounterbalance 29 is found at th
44、e rear side of the balance arm15. The movable counterbalance 29 is shifted along the balancearm to adjust the force caused by the counterbalance mass. Thefixation screw 18 (knurled screw) fixes the counterbalance 29on the balance arm. For more precise adjustment of the forceFIG. 1 Ring Shear Tester
45、(Overall View)D6773083caused by the counterbalance mass, the balance arm 15 isprovided additionally with a smaller movable mass 30. Afterunscrewing the knurled screw, which is the major part of themovable mass 30, the movable mass 30 can be shifted alongthe balance arm. When the counterbalance mass
46、is welladjusted, the lid, crossbeam, tie rods, and hanger do not presson the bulk solid; that is, the vertical stress at the surface of thebulk solid is equal to zero.6.6 A digital displacement indicator 31 (Fig. 7) is used forthe measurement of the height of the bulk solid specimen.6.7 Bolts at the
47、 ends of the crossbeam 8 are used to appendthe tie rods 13. Therefore, a circular hole is at one end of eachtie rod 13. The opposite end is provided with an elongated holefor suspending in the adjustable seating 16 attached to the loadbeam 17. The seatings 16 are adjustable to enable the align-ment
48、of the horizontal position of the lid 7.6.8 The rotation of the lid 7 is prevented by the tie rods 13which transfer the tensile force to the load beams 17.6.9 The bottom part of the hanger 11, which hangs on thecrossbeam 8 and serves for exerting a normal load N on thebulk solid, is located within t
49、he base 1 (Fig. 1). The hanger hasa circular plate 19 at its lower end for holding the applied masspieces.6.10 The base 1 has four adjustable stands 3 (Fig. 5) to levelthe Ring Shear Tester.6.11 For control of the motor drive a front panel 35 (Fig. 3)is at the front side of the casing 2.6.12 The load beams 17 are connected parallel. Each loadbeam should be capable of measuring a force up to 200 N witha precision of 0.02 % of full scale. Thus, the total measuringrange, which is twice the measuring range of one load beam, is400 N. The signal from t
