1、Designation: D 6773 02Standard Shear Test Method forBulk Solids Using the 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 revisi
2、on. A number in parentheses indicates the year of last reapproval. Asuperscript epsilon (e) indicates an editorial change since the last revision or reapproval.1. Scope1.1 This method covers the apparatus and procedures formeasuring the unconfined yield strength of bulk solids duringboth continuous
3、flow and after storage at rest. In addition,measurements of internal friction, bulk density, and wallfriction on various wall surfaces are included. The SI system ofunits has been used throughout.1.2 The most common use of this information is in thedesign of storage bins and hoppers to prevent flow
4、stoppagesdue to arching and ratholing, including the 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 o
5、fdifferent products or optimization.1.3 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 standard to establish appro-priate safety and health practices and determine the applica-bility of regulatory limi
6、tations prior to use.2. Referenced Documents2.1 ASTM Standards:D 653 Terminology Relating to Soil, Rock, and ContainedFluids2D 6128 Standard Shear Testing Method for Bulk SolidsUsing the Jenike Shear Cell33. Terminology3.1 Definitions of terms used in this test method are inaccordance with Terminolo
7、gy D 653.3.2 adhesion test, na static wall friction test with timeconsolidation.3.3 angle of internal friction, fi, nthe angle between theaxis of normal stress (abscissa) and the tangent to the yieldlocus.3.4 angle of wall friction, f8, nthe arctan of the ratio ofthe wall shear stress to the wall no
8、rmal stress.3.5 bin, na container or vessel for holding a bulk solid,frequently consisting of a vertical cylinder with a converginghopper. Sometimes referred to as silo, bunker or elevator.3.6 bulk density, rb, nthe mass of a quantity of a bulksolid divided by its total volume.3.7 bulk solid, nan as
9、sembly of solid particles handled insufficient quantities that its characteristics can be described bythe properties of the mass of particles rather than the charac-teristics of each individual particle. It may also be referred toas a granular material, particulate solid, or powder. Examplesare suga
10、r, flour, and ore.3.8 bunker, nsynonym for bin, but sometimes understoodas being a bin without any or only a small vertical part at thetop of the hopper.3.9 consolidation, nthe process of increasing the uncon-fined yield strength of a bulk solid.3.10 critical state, na state of stress in which the b
11、ulkdensity of a bulk solid and the shear stress in the shear zoneremain constant during shear under constant normal stress.3.11 effective angle of friction, d, nthe inclination of theeffective yield locus (EYL).3.12 effective yield locus (EYL), nstraight line passingthrough the origin of the s, t-pl
12、ane and tangential to the steadystate Mohr circle, corresponding to steady state flow conditionsof a bulk solid of given bulk density.3.13 elevator, nsynonym for bin. Commonly used in thegrain industry.3.14 failure (of a bulk solid), nplastic deformation of anoverconsolidated bulk solid subject to s
13、hear, causing dilationand a decrease in strength.3.15 flow, steady state, ncontinuous plastic deformationof a bulk solid at critical state.3.16 flow function, FF, nthe plot of unconfined yieldstrength versus major consolidation stress for one specific bulksolid.3.17 granular material, nsynonym for b
14、ulk solid.3.18 hopper, nthe converging portion of a bin.3.19 major consolidation stress, s1, nthe major principalstress given by the Mohr stress circle of steady state flow. ThisMohr stress circle is tangential to the effective yield locus.3.20 Mohr stress circle, nthe graphical representation of a1
15、This test method is under the jurisdiction of ASTM 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 March 10, 2002. Published April 2002.2Annual Book of ASTM Standards, Vol 04.08.
16、3Annual Book of ASTM Standards, Vol 04.09.1Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.state of stress in coordinates of normal and shear stress, that is,in the s, t-plane.3.21 normal stress, s, nthe stress acting normally to thec
17、onsidered plane.3.22 particulate solid, nsynonym for bulk solid.3.23 powder, nsynonym for bulk solid, particularly whenthe particles of the bulk solid are fine.3.24 silo, nsynonym for bin.3.25 shear test, nan experiment to determine the flowproperties of a bulk solid by applying different states of
18、stressand strain to it.3.26 shear tester, nan apparatus for performing sheartests.3.27 time angle of internal friction, ft, ninclination of thetime yield locus of the tangency point with the Mohr stresscircle passing through the origin.3.28 time yield locus, nthe yield locus of a bulk solidwhich has
19、 remained at rest for a certain time under a givennormal stress for a certain time.3.29 unconfined yield strength, fc, nthe major principalstress of the Mohr stress circle being tangential to the yieldlocus with the minor principal stress being zero.3.30 wall normal stress, sw, nthe normal stress pr
20、esent ata confining wall.3.31 wall shear stress, tw, nthe shear stress present at aconfining wall.3.32 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 wallshear stress to wa
21、ll normal stress.3.33 yield locus, nplot of shear stress versus normal stressat 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 sample of bulk solid is placed in a shearcell of s
22、pecific 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 by shearing the specime
23、nunder 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 preshear and shearsteps.4.5 A
24、 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 leaving the loadon the specime
25、n 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 arching and ratholing areco
26、mmon. 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 properties of bulk solid
27、s, anddesigning bins and hoppers based on these flow properties,most flow problems can be prevented or eliminated (1).45.3 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 governed by the fines (6
28、 mmfraction). For such bulk solids, strength and wall friction testsmay be performed on the fine fraction only.6. Apparatus6.1 The Schulze 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 Th
29、e driving axle 5 (with detachable plastic cap 6) causesthe shear cell 4 to rotate. The driver pins at the underside of theshear cell must set in the toothed wheel at the driving axle 5 toensure a close connection between shear cell and driving axle.The driving axle is driven by an electric motor and
30、 can rotateto the right or to the left. In order to shear the bulk solidsample, the driving axle 5 along with the shear cell 4 rotateclockwise (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 s
31、hear 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 shearcell 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 1The standard cell has 20 bars,
32、 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 crossbeam 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 sta
33、nding out from the driving axle can be seen). Rollersat the ends of the crossbeam and the removable guide rollers 12prevent movement of 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 counterweight
34、 29 (Fig. 6) serves to compensate for theweights of lid 7, crossbeam 8, hanger 11, and tie rods 13. Thecounterweight 29 is found at the rear side of the balance arm15. The movable counterweight 29 is shifted along the balancearm to adjust the counterweight force. The fixation screw 18(knurled screw)
35、 fixes the counterweight 29 on the balance arm.For more precise adjustment of the counterweight force, thebalance arm 15 is provided additionally with a smaller movableweight 30. After unscrewing the knurled screw, which is the4The boldface numbers in parentheses refer to the list of references at t
36、he end ofthis standard.D6773022major part of the movable weight 30, the movable weight 30can be shifted along the balance arm. When the counterbalanceweight is well adjusted, the lid, crossbeam, tie rods, and hangerdo not press on the bulk solid sample; that is, the vertical stressat the surface of
37、the bulk solid sample is equal to zero.6.6 A digital displacement indicator 31 (Fig. 7) is used forthe measurement of the height of the bulk solid sample.6.7 Bolts at the 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 opposi
38、te 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 adjust-ment 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 f
39、orce 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 sample, is located within the base 1 (Fig. 1). Thehanger has a circular plate 19 at its lower end for holding theweight pieces.6.10 The base 1 has fo
40、ur adjustable stands 3 (Fig. 5), withwhich the Ring Shear Tester is to be adjusted accurately in ahorizontal position.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 me
41、asuring 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 the force transducer is conditioned byan amplifier and shown on a recorder.NOTE 2Danger! To avoid overloading of the load
42、 beams, the indi-cated maximum normal load must not be exceeded!6.13 For the Schulze Ring Shear Tester RST-01.01 differentshear cells are available. The dimensions of the Standard celland a smaller cell can be taken from Table 2 and Fig. 8. Forspecial purposes (for example, reduced internal volume)
43、otherdimensions are also available.6.14 The time consolidation bench serves for the storage ofshear cells with bulk solid samples under load.6.14.1 The time consolidation bench (Fig. 9) is composed ofa frame Z1, on which are fastened three supporting plates Z2.One small shear cell (type S, volume ap
44、prox. 200 cm3) can beplaced on each plate. The shape of the plate Z2 centers theshear cell.6.14.2 Through the central depression of the time consoli-dation crossbeam 26 the normal load is exerted during timeFIG. 1 Ring Shear Tester (Overall View)D6773023consolidation as shown in the left part of Fig
45、. 9. The lower endof the loading rod Z4 is equipped with a central tip.6.14.3 The transparent cylindrical plastic cap Z3, whenpressed on plate Z2, protects the samples from the surroundingatmosphere (for example, to reduce changes of the moisture ofthe bulk solid samples). This cap Z3 is joined to t
46、he loading rodZ4 through a rubber bellows Z8.6.14.4 At the upper end of the loading rod Z4 a disk Z5 isfastened for supporting weight pieces by which the verticalload for time consolidation is applied.6.14.5 The fixing screw Z6 serves for the fixation of theloading rod Z4 in the upper position (Fig.
47、 9, on the right). Formoving the loading rod upwards or downwards, the fixingscrew must be unscrewed somewhat. In the loading position(Fig. 9, on the left) the fixing screw must remain unscrewed.6.14.6 For horizontal alignment, the time consolidationbench is provided with four adjustable feet Z7.6.1
48、5 The wall friction cells allow the measurement of wallyield loci from which wall friction angles can be calculated.6.15.1 The bottom ring 48 of the wall friction cell (see Fig.10) contains the wall material sample to be tested. The wallmaterial coupon is placed on an appropriate number of spacerrin
49、gs 51. The thickness of each spacer ring is 2 mm.6.15.2 To prevent any relative circumferential displacementbetween the bottom ring 48 and the wall material coupon, fourdriving pins 50 are installed at the outer wall of the bottom ring48. The annular wall material coupon has to be provided withnotches for these driving pins so that bottom ring and wallmaterial coupon are interlocked. The required dimensions ofthe wall material coupon are shown in Fig. 11.6.15.3 The lid 49 (Fig. 12) has bent bars from stainless steelto prevent slipping of the bulk solid
