1、Designation: D6916 18Standard Test Method forDetermining the Shear Strength Between SegmentalConcrete Units (Modular Concrete Blocks)1This standard is issued under the fixed designation D6916; the number immediately following the designation indicates the year oforiginal adoption or, in the case of
2、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. Scope1.1 This test method is used to determine the shear strengthbetween two layers of segmental concrete
3、 block units used inconstruction of reinforced soil retaining walls. The test iscarried out under conditions determined by the user thatreproduce the facing system at full scale. The results of a seriesof tests are used to define a relationship between shear strengthdeveloped between segmental concr
4、ete units and normal load.1.2 This is a performance test used to determine propertiesfor design of retaining wall systems utilizing segmental con-crete units and soil reinforcing geosynthetics, either geotextilesor geogrids. The test is performed on a full-scale constructionof the facing system and
5、may be run in a laboratory or the field.1.3 The values stated in SI units are regarded as thestandard. The values stated in inch-pound units are providedfor information only.1.4 This standard does not purport to address all of thesafety concerns, if any, associated with its use. It is theresponsibil
6、ity of the user of this standard to establish appro-priate safety, health, and environmental practices and deter-mine the applicability of regulatory limitations prior to use.1.5 This international standard was developed in accor-dance with internationally recognized principles on standard-ization e
7、stablished in the Decision on Principles for theDevelopment of International Standards, Guides and Recom-mendations issued by the World Trade Organization TechnicalBarriers to Trade (TBT) Committee.2. Referenced Documents2.1 ASTM Standards:2D448 Classification for Sizes of Aggregate for Road andBrid
8、ge ConstructionD4354 Practice for Sampling of Geosynthetics and RolledErosion Control Products (RECPs) for TestingD4439 Terminology for GeosyntheticsD4595 Test Method for Tensile Properties of Geotextiles bythe Wide-Width Strip MethodD6637/D6637M Test Method for Determining Tensile Prop-erties of Ge
9、ogrids by the Single or Multi-Rib TensileMethod3. Terminology3.1 Definitions:3.1.1 displacement criteria, na user-prescribed maximummovement, mm (in.), of the top segmental concrete unit outfrom the back of lower segmental concrete units.3.1.2 geosynthetic, na planar product manufactured frompolymer
10、ic material used with soil, rock, earth, or other geo-technical engineering-related material as an integral part of amanmade project, structure, or system. D44393.1.3 granular infill, ncoarse-grained soil aggregate usedto fill the voids in and between segmental concrete units.3.1.4 peak shear streng
11、th, nthe maximum shear capacitybetween segmental concrete units.3.1.5 segmental concrete depth, nthe segmental concreteunit dimension perpendicular to the wall face.3.1.6 segmental concrete unit (modular concrete block),na concrete unit manufactured specifically for mortarless,dry-stack retaining wa
12、ll construction.3.1.7 segmental concrete unit width, nthe segmental con-crete unit dimension parallel to the wall face.3.2 For definitions of other terms relating to geosynthetics,refer to Terminology D4439.4. Summary of Test Method4.1 In this test method, segmental concrete units are as-sembled in
13、two rows (layers). The bottom row is laterallyrestrained. The top row is loaded vertically to a constantsurcharge load, and the interface is sheared at a constant rate ofdisplacement until a drop of load after the peak load occurs.The test may be run with the geosynthetic reinforcementsandwiched bet
14、ween the two rows of segmental concrete units1This test method is under the jurisdiction of ASTM Committee D35 onGeosynthetics and is the direct responsibility of Subcommittee D35.01 on Mechani-cal Properties.Current edition approved July 15, 2018. Published August 2018. Originallyapproved in 2003.
15、Last previous edition approved in 2011 as D6916 06c (2011).DOI: 10.1520/D6916-18.2For referenced ASTM standards, visit the ASTM Web Site, www.astm.org. orcontact ASTM Customer Service at serviceastm.org. For Annual Book of ASTMStandards volume information, refer to the standards Document Summary pag
16、e onthe ASTM web site.Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United StatesThis international standard was developed in accordance with internationally recognized principles on standardization established in the Decision on Principles for t
17、heDevelopment of International Standards, Guides and Recommendations issued by the World Trade Organization Technical Barriers to Trade (TBT) Committee.1to determine the shear strength between segmental concreteunits at the connection between the units and the geosyntheticreinforcement.5. Significan
18、ce and Use5.1 The shear strength between segmental concrete units(with and without geosynthetic reinforcement) is used indesign of reinforced soil retaining walls.5.2 This test is used to determine the shear strength for thedesign of the facing stability of segmental retaining walls.Performing a ser
19、ies of these shear tests at varying normal loadspermits development of a relationship between shear strengthand normal load. This relationship may be linear, bilinear, orsome other complex mathematical expression.5.3 This shear strength test is meant to be a performance test(laboratory or field); th
20、erefore, it should be conducted usingfull-scale system components. The conditions for the test areselected by the user and are not for routine testing.5.4 As a performance test on full-scale system components,it accounts for some of the variables in construction proceduresand materials tolerance nor
21、mally present for these types ofretaining wall systems.6. Apparatus6.1 Testing SystemAn example of a test apparatus andsetup is illustrated in Fig. 1. The principal components of thetest apparatus are:6.1.1 Loading Frame.6.1.2 Normal Load Piston/Actuator.6.1.3 Vertical Loading Platen, with stiff rub
22、ber mat orairbag to apply uniform vertical pressure to top of concreteblocks.6.1.4 Vertical Load Cell, to measure normal load.6.1.5 Horizontal Piston/Actuator, to apply horizontal loadon the top segmental concrete unit.6.1.6 Horizontal Load Cell, to measure applied force on thetop segmental concrete
23、 unit.6.1.7 Two (2) Horizontal Displacement MeasurementDevices, to record displacement of the top segmental concreteunit.6.2 Loading FrameThe loading frame shall have suffi-cient capacity to resist the forces developed by the horizontaland vertical loading pistons/actuators.6.3 Shear Loading PlateTh
24、e shear loading plate must besufficiently rigid to apply a uniform force across the full widthof the top course. For some segmental units, it may benecessary to apply the load through a deformable material (thatis, stiff rubber) which will conform to an irregular blocksurface, thereby allowing for a
25、 uniform load distribution.6.4 Restraining Box/PlateA rigid restraining box/plate isrequired to prevent horizontal movement of the lowermostsegmental concrete units during shear testing. The restrainingbox/plate area shall be of sufficient width and depth toaccommodate the full-scale “as-manufacture
26、d” segmental con-crete units being tested.6.5 Shear Loading AssemblyThe tensile loading unit willgenerally be a constant rate of extension screw jack orFIG. 1 Shear Test Apparatus (Cross Section View)D6916 182hydraulic actuator that can be displacement rate controlled.The loading equipment shall hav
27、e a capacity that is at leastequal to 120 % of the anticipated shear strength of thesegmental concrete units. The piston shall be capable of at least150 mm (6 in.) of movement in order to facilitate test setup andto ensure that there is adequate stroke to achieve peak load. Theorientation of the ten
28、sioning force shall be horizontal andperpendicular to the back of the segmental units. The horizon-tal loading arrangement must not permit rotation of the topconcrete unit during shear.6.6 Load CellsA calibrated load cell shall be used tomeasure the shear force and normal load during the test. Thelo
29、ad cell used for measuring shear shall have a capacity that isgreater than or equal to 120 % of the anticipated shear forcebetween units. The load cell used for measuring the normalsurcharge load shall have a capacity that is greater than orequal to 100 % of the maximum anticipated normal load. Thel
30、oad cells shall be accurate to within 60.5 % of its full-scalerange.6.7 Displacement Measuring DevicesTwo (2) linear vari-able displacement transducers (LVDTs) or similar electronicdisplacement measuring devices are recommended to continu-ously monitor the displacement of the top segmental concreteu
31、nit out from the back of the lower segmental concrete units.Alternatively, dial gauges may be read and recorded manuallyat regular intervals not greater than 1 min. LVDTs, dial gauges,or similar measuring devices shall be accurate to 60.1 mm(0.005 in.).7. Sampling7.1 Segmental Concrete Units:7.1.1 S
32、egmental concrete units shall be full-size blocks andmeet the manufacturers material and dimensional specifica-tions. Model or prototype units shall not be used unless it canbe demonstrated that they are equivalent to production units.7.1.2 The user shall specify or collect (or both) a sufficientsam
33、ple of representative segmental units, from a standardproduction lot, to construct the anticipated number of testconfigurations for the shear system within the testing agencysload frame and testing system.7.1.3 The shear interface must be constructed with full-sizeor modified (see 7.1.4) segmental c
34、oncrete units randomlyselected from the users sampling of a standard production lot;see 7.1.2.7.1.4 Test WidthThe width of the shear interface fortesting shall be constructed to a minimum of 152.4 mm (6 in.)in width. The test section shall consist of at least two bottomcourse segmental concrete unit
35、s, with one top course segmentalunit placed on top of the lower segmental concrete units. Theshear interface shall include at least one typical segmentalconcrete unit running bond joint. The top unit must be the fullwidth of the unit. The bottom units may be adjusted to fit intothe test apparatus. T
36、esting of segmental concrete unit widthsgreater than 500 mm (19.7 in.) may be represented in this testby limiting the test wall to 1000 mm (39.4 in.) in width.NOTE 1Any modification to the width of bottom units shouldmaintain the integrity of the test shear interface and ensure that arepresentative
37、(repeatable) test shear interface is maintained.7.1.5 Test HeightThe height of the segmental concreteunit may be reduced to facilitate handling and safety issues.Any modification to the segmental concrete unit height shallnot alter the geometry of the test shear interface and shall beclearly stated
38、in the test report (see 10.2).7.1.6 ConditioningThe segmental concrete unit test speci-men shall be brought to standard temperature and relativehumidity conditions for testing in a laboratory. The temperatureis to be 21 6 2 C (70 6 4 F) and the relative humidity 65 610 %. For field testing, the spec
39、imen shall be brought toambient conditions for not less than 1 h. The temperature andhumidity at the start and end of the test shall be recorded forfield testing.7.2 Geosynthetic (If Required):7.2.1 If the segmental concrete units are to be used for ageosynthetic-reinforced segmental retaining wall,
40、 then a layerof a specified geosynthetic material shall be placed between thesegmental concrete units.7.2.2 Sampling RequirementsThe latest version of ASTMsampling protocol for geotextiles (Practice D4354) shall beused for the geosynthetic reinforcement material.7.2.3 ConditioningThe geosynthetic re
41、inforcement testspecimen shall be brought to standard temperature and relativehumidity conditions for testing in a laboratory. The temperatureis to be 21 6 2 C (70 6 4 F) and the relative humidity 60 610 %. For field testing, the specimen shall be brought toambient conditions for not less than 1 h.
42、The temperature andhumidity at the start and end of the test shall be recorded forfield testing.7.2.4 Specimen WidthWhen included, the geosyntheticreinforcement test specimen shall be the full width of the sheartest interface.7.2.5 Specimen LengthThe geosynthetic specimen shallhave sufficient length
43、 to cover the interface surface as specifiedby the user. The specimen must be trimmed to providesufficient anchorage at the actuator side of the test apparatus toprevent slippage of the front edge of the geosynthetic sample.7.2.6 A new geosynthetic reinforcement test specimen shallbe used for each t
44、est.7.2.7 Number of TestsA sufficient number of tests shall beconducted to adequately define a relationship between shearstrength and normal load. Tests shall be conducted at aminimum of five (5) unique normal loads within the range ofloads typical of wall design, as directed by the user.Additionall
45、y, at least two more tests at one normal load will benecessary to verify repeatability (see 7.2.8).7.2.8 Repeatability of Test ResultsThe testing agency shallprovide evidence of test results repeatability by conducting atleast three tests at one normal load level for a specificsegmental concrete uni
46、t and geosynthetic reinforcement sys-tem. The general range for repeatability of peak shear strengthof these three nominally identical tests is 610 % from theD6916 183mean of the three tests. If the test results are outside of thisrange, it shall be duly noted on the report.8. Procedure8.1 Install a
47、nd brace lower course of concrete segmentalunits. Place the units such that a running joint will be locatedalong the centerline of the test apparatus.8.1.1 The facing system shall be constructed using thegeosynthetic reinforcement (if required), granular infill, full-scale segmental concrete block u
48、nits, and connectors specifiedby the user. The number, type, and arrangement of mechanicalconnectors shall also be specified by the user.8.1.2 A single course of segmental units shall be placed ona rigid base. A single segmental concrete unit will later (see8.5) be placed over the bottom course of u
49、nits, with thegeosynthetic reinforcement located and placed between thesecourses as described by the user or in the same manneranticipated for field construction.8.2 Place and compact granular infill within (if required)and between the segmental concrete units to the densityspecified by the user.8.2.1 The granular infill for testing shall be specified by theuser.NOTE 2Atypical granular infill would be crushed stone conforming tothe size number 57 or 67 gradations in Classification D448.8.3 Center geosynthetic reinforcement on the running bondjoint o
