1、Designation: D6128 06D6128 14Standard Test Method forShear Testing of Bulk Solids Using the Jenike Shear Cell1This standard is issued under the fixed designation D6128; the number immediately following the designation indicates the year oforiginal adoption or, in the case of revision, the year of la
2、st 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 method 2covers the apparatus and procedures for measuring the cohesive strength of bulk solids during both continu
3、ousflow and after storage at rest. In addition, measurements of internal friction, bulk density, and wall friction on various wall surfacesare included.1.2 This standard is not applicable to testing bulk solids that do not reach the steady state requirement within the travel limitof the shear cell.
4、It is impossibledifficult to classify ahead of time which bulk solids cannot be tested, but one example may be thoseconsisting of highly elastic particles.1.3 The values stated in SI units are to be regarded as standard.1.3 The most common use of this information is in the design of storage bins and
5、 hoppers to prevent flow stoppages due toarching and ratholing, including the slope and smoothness of hopper walls to provide mass flow. Parameters for structural designof such equipment also may be derived from this data.1.4 All observed and calculated values shall conform to the guidelines for sig
6、nificant digits and rounding established in PracticeD6026.1.4.1 The procedures used to specify how data are collected/recorded or calculated, in this standard are regarded as the industrystandard. In addition, they are representative of the significant digits that generally should be retained. The p
7、rocedures used do notconsider material variation, purpose for obtaining the data, special purpose studies, or any considerations for the users objectives;and it is common practice to increase or reduce significant digits of reported data to be commensurate with these considerations.It is beyond the
8、scope of this standard to consider significant digits used in analysis methods for engineering design.1.5 UnitsThe values stated in SI units are to be regarded as standard. No other units of measure are included in this standard1.6 This standard does not purport to address all of the safety concerns
9、, 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 prior to use.2. Referenced Documents2.1 ASTM Standards:3D653 Terminology Relating to Soil, Rock, and C
10、ontained FluidsD2216 Test Methods for Laboratory Determination of Water (Moisture) Content of Soil and Rock by MassD3740 Practice for Minimum Requirements for Agencies Engaged in Testing and/or Inspection of Soil and Rock as Used inEngineering Design and ConstructionD6026 Practice for Using Signific
11、ant Digits in Geotechnical Data3. Terminology3.1 Definitions:3.1.1 Definitions of terms used in this test method are in accordance with Terminology D653.3.1.2 adhesion test, na static wall friction test with time consolidation.1 This testing method is under the jurisdiction of ASTM Committee D18 on
12、Soil and Rock and is the direct responsibility of Subcommittee D18.24 on Characterizationand Handling of Powders and Bulk Solids.Current edition approved Dec. 1, 2006Sept. 1, 2014. Published January 2007September 2014. Originally approved in 1997. Last previous edition approved in 20002006as D6128 0
13、0.D6128 06. DOI: 10.1520/D6128-06.10.1520/D6128-14.2 This test method is based on the “Standard Shear Testing Technique for Particulate Solids Using the Jenike Shear Cell,” a report of the EFCE Working Party on theMechanics of Particulate Solids. Copyright is held by the Institution of Chemical Engi
14、neers and the European Federation of Chemical Engineering.3 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 website.Thi
15、s 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 to adequately depict all changes accurately, ASTM recommends that users consult prior editio
16、ns 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 standardCopyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959.
17、United States13.1.3 angle of internal friction, i, nthe angle between the axis of normal stress (abscissa) and the tangent to the yield locus.3.1.4 angle of wall friction, , n the arctan of the ratio of the wall shear stress to the wall normal stress.3.1.5 bin, na container or vessel for holding a b
18、ulk solid, frequently consisting of a vertical cylinder with a converging hopper.Sometimes referred to as silo, bunker, or elevator.3.1.6 bulk density, b, nthe mass of a quantity of a bulk solid divided by its total volume3.1.7 bulk solid, nan assembly of solid particles handled in sufficient quanti
19、ties that its characteristics can be described by theproperties of the mass of particles rather than the characteristics of each individual particle. May also be referred to as granularmaterial, particulate solid, or powder. Examples are sugar, flour, ore, and coal.3.1.8 bunker, nsynonym for bin, bu
20、t sometimes understood as being a bin without any or only a small vertical part at the topof the hopper.3.1.9 cohesive strength, nsynonym for unconfined yield strength.3.1.10 consolidation, nthe process of increasing the strength of a bulk solid.3.1.11 critical state, na state of stress in which the
21、 bulk density of a bulk solid and the shear stress in the shear zone remainconstant.3.1.12 effective angle of friction, , nthe inclination of the effective yield locus (EYL).3.1.13 effective yield locus (EYL), nstraight line passing through the origin of the , -plane and tangential to the steady sta
22、teMohr circle, corresponding to steady state flow conditions of a bulk solid of given bulk density.3.1.14 elevator, nsynonym for bin, commonly used in the grain industry.3.1.15 failure (of a bulk solid), nplastic deformation of an overconsolidated bulk solid subject to shear, causing dilation anda d
23、ecrease in strength.3.1.16 flow, steady state, ncontinuous plastic deformation of a bulk solid at critical state.3.1.17 flow function, FF, nthe plot of unconfined yield strength versus major consolidation stress for one specific bulk solid.3.1.18 granular material, nsynonym for bulk solid.3.1.19 hop
24、per, nthe converging portion of a bin.3.1.20 major consolidation stress, 1, nthe major principal stress given by the Mohr stress circle of steady state flow. ThisMohr stress circle is tangential to the effective yield locus.3.1.21 Mohr stress circle, nthe graphical representation of a state of stres
25、s in coordinates of normal and shear stress, that is,in the ,-plane.3.1.22 normal stress, , nthe stress acting normally to the considered plane.3.1.23 overconsolidated specimen, na condition in which the shear force passes through a maximum and then decreasesduring preshear.3.1.24 particulate solid,
26、 nsynonym for bulk solid.3.1.25 powder, nsynonym for bulk solid, particularly when the particles of the bulk solid are fine.3.1.26 silo, nsynonym for bin.3.1.27 shear test, nan experiment to determine the flow properties of a bulk solid by applying different states of stress andstrain to it.3.1.28 s
27、hear tester, nan apparatus for performing shear tests.3.1.29 time angle of internal friction, t, ninclination of the time yield locus of the tangency point with the Mohr stress circlepassing through the origin.3.1.30 time yield locus, nthe yield locus of a bulk solid which has remained at rest under
28、 a given normal stress for a certaintime.3.1.31 unconfined yield strength, fc, n the major principal stress of the Mohr stress circle being tangential to the yield locuswith the minor principal stress being zero. A synonym for compressive strength.3.1.32 underconsolidated specimen, na condition in w
29、hich the shear force increases continually during preshear.3.1.33 wall normal stress, w, n the normal stress present at a confining wall.3.1.34 wall shear stress, w, nthe shear stress present at a confining wall.3.1.35 wall yield locus, na plot of the wall shear stress versus wall normal stress. The
30、 angle of wall friction is obtained fromthe wall yield locus as the arctan of the ratio of the wall shear stress to wall normal stress.3.1.36 yield locus, nplot of shear stress versus normal stress at failure. The yield locus (YL) is sometimes called theinstantaneous yield locus to differentiate it
31、from the time yield locus.D6128 1423.1 For common definitions of technical terms in this standard, refer to Terminology D653.4. Summary of Test Method4.1 A representative samplespecimen of bulk solid is placed in a shear cell of specific dimensions. This specimen ispreconsolidated by twisting the sh
32、ear cell cover while applying a compressive load normal to the cover.4.2 When running an instantaneous or time shear test, a normal load is applied to the cover, and the specimen is presheared untila steady state shear value has been reached.4.3 An instantaneous test is run by shearing the specimen
33、under a reduced normal load until the shear force goes through amaximum value and then begins to decrease.4.4 A time shear test is run similarly to an instantaneous shear test, except that the specimen is placed in a consolidation benchbetween preshear and shear.4.5 A wall friction test is run by sl
34、iding the specimen over a coupon of wall material and measuring the frictional resistanceas a function of normal, compressive load.4.6 A wall friction time test involves sliding the specimen over the coupon of wall material, leaving the load on the specimenfor a predetermined period of time, then sl
35、iding it again to see if the shearing force has increased.5. Significance and Use5.1 Reliable, controlled flow of bulk solids from bins and hoppers is essential in almost every industrial facility. Unfortunately,flow stoppages due to arching and ratholing are common. Additional problems include unco
36、ntrolled flow (flooding) of powders,segregation of particle mixtures, useable capacity which is significantly less than design capacity, caking and spoilage of bulksolids in stagnant zones, and structural failures.5.2 By measuring the flow properties of bulk solids, and designing bins and hoppers ba
37、sed on these flow properties, most flowproblems can be prevented or eliminated.5.3 For bulk solids with a significant percentage of particles (typically, one third or more) finer than about 6 mm (mm, 14 in.),the cohesive strength is governed by the fines (-6-mm fraction). For such bulk solids, cohes
38、ive strength and wall friction tests maybe performed on the fine fraction only.NOTE 1The quality of the result produced by this test method is dependent on the competence of the personnel performing it, and the suitability ofthe equipment and facilities used. Agencies that meet the criteria of Pract
39、ice D3740 are generally considered capable of competent and objectivetesting/sampling/inspection/etc. Users of this test method 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 eva
40、luating some of those factors. Practice D3740 was developed foragencies engaged in the testing and/or inspection of soil and rock. As such it is not totally applicable to agencies performing this test method. However,users of this test method should recognize that the framework of Practice D3740 is
41、appropriate for evaluating the quality of an agency performing thistest method. Currently there is no known qualifying national authority that inspects agencies that perform this test method.6. Apparatus6.1 The Jenike shear cell is shown in Fig. 1. It consists of a base (1), shear ring (2), and shea
42、r lid (3), the latter having a bracket(4) and pin (5). Before shear, the ring is placed in an offset position as shown in Fig. 1, and a vertical force Fv is applied to thelid, and hence, to the particulate solid within the cell by means of a weight hanger (6) and weights (7).Ahorizontal force is app
43、liedto the bracket by a mechanically driven measuring stem (8).FIG. 1 Jenike Cell in Initial Offset PositionD6128 1436.2 It is especially important that the shear force measuring force-measuring stem acts on the bracket in the shear plane (planebetween base and shear ring) and not above or below thi
44、s plane.6.3 The dimensions of the Jenike shear cells supplied by Jenike thus, for the purpose of this test method, they are ignored.NOTE 18Points to the left of Point A are ignored because they represent a state where tensile stresses can occur in the shear cell. This can be seenby considering the y
45、ield point on Fig. 14 marked by S(), below Point A. If a Mohr circle 3 is drawn through this point, which is tangential to theextrapolated yield locus, part of that circle will lie to the left of the origin indicating negative normal stresses, that is, tensile stresses.8.2 Shear Testing Procedure fo
46、r Time Consolidation:8.2.1 When a particulate solid is exposed to a normal or compressive stress for some time it may gain strength. This gain instrength may be measured in the Jenike shear cell, and the effect is called time consolidation.8.2.2 Time consolidation is carried out using a consolidatin
47、g bench, which consists of several shear cells that can be loadedindependently. The time that the specimens sit at rest is specified according to the application.NOTE 19As an alternative to using a consolidation bench, consider the following: a critically consolidated specimen is prepared by preshea
48、ring withweight mWp.After attaining steady state flow the advance of the force measuring force-measuring stem is stopped but the stem is not retracted. The shearzone formed thus remains under the normal and shear stresses corresponding to steady state flow and is kept in this state for a definite ti
49、me, t. If the stemis then retracted, the shear force will drop to zero, and the actual shear test may be performed in the usual way. It is found that with materials which gainstrength during time consolidation, a higher shear strength will be measured. In a ,-diagram, the time yield locus for time consolidation will lie abovethe instantaneous flow yield locus. If the effect of time consolidation in the Jenike shear cell were measured in this manner, one test would monopolizethe shear cell for a very long time. Also, cre
