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886048 Engineering application of direct and simple shear testing
26lA
Influence of stress-release disturbance, storage, and reconsolidation procedures on the shear hehaviour of reconstituted underwater clay Graham, J; Lau, S L K Georechnique V38, N2, June 1988, P279-300 Changes in undrained shear strength, pore pressure, and compressibility due to sampling, offloading, storage, and reconsolidation have been examined. Samples of normally and overconsolidated illite clays were prepared by anisotropic consolidation and tested immediately and after unloading, storage in the drained or undrained state, and reconsolidation by various procedures. Results varied considerably. Suitable practices for valid and consistent results are discussed.
To overcome frictional effects in a large scale plane strain apparatus. Technical note Matthews, R S; Boot, J C Geotechnique V38, N2, June 1988, P311-315 An economic low friction layer to minimise boundary shear stress in a 3mx3mx0.225m plane strain laboratory testing machine is described. The soil is confined between layers of foam rubber, and overlapping polythene tiles and glass ballotini are between this and the steel plates of the apparatus. Soil/container friction coefficient is maintained at 0.03-o. 10 for a wide range of stresses.
Experimental study of the elasticity of mylonite rock with random cracks Oda, M Inr J Rock Mech Min Sci V25, N2, April 1988, P59-69 An elastic compliance tensor for discontinuous rock masses has been formulated by treating each crack with an elastic equivalent, a set of parallel plates connected by 2 springs. Uniaxial compressive tests on 8 mylonite samples with various crack geometries were used to verify the theory. The results indicate that samples with different crack geometries can be compared generally with the help of crack tensor theory, the spring model is an acceptable idealization of elastic deformation of cracks if hysteresis of springs is taken into account, and that local strain is variable, but mean strain can be related to overall crack tensor.
886052 Siulatioa of borehole breakouts in a model material: technical note Perie, P J; Goodman, R E; Doe, T J Int J Rock Mech Min Sci V25, N2, April 1988, P97-98 A method to observe the progression of failure around a hole, using a bag of flour and a length of metal tubing, is presented. After ‘drilling’ the hole, failure is induced by squeezing the bag, creating a deviatoric horizontal stress, until breakout. Breakout appears in the direction of minimum squeezing, confirming a relation widely held with regard to rocks.
Engineering application of direct and simple shear testing Matthews, M C Ground Engng VZI, N2, March 1988, P13-21 The development of shear testing methods is described. The advantages and disadvantages of direct shear box tests, ring shear tests, simple shear tests and interface shear testing are discussed. Direct and simple testing are seen to offer greater similitude with the field prototype than triaxial tests, although uncertainty over non-uniform conditions means triaxial tests are the industry standard. 42 refs. 886049 Resistance of coal at temperature to direct shear (In French) Luong, M P; Schmitt, N h&she Minerale V69, NlO, Dee 1987. P390-392 A direct shear test was used to measure simple compression and shear behaviour of heterogeneous, anisotropic coal samples over a range of temperatures. Results indicate that cohesion decreases as the temperature rises, and decreases more rapidly than resistance to compression. At 750 deg C the material has lost 75% of its cohesion. The tests were part of a series to determine different points of the intrinsic fracture curve.
Petrography, structure and mechanical behaviour of coals Homand-Etienne, F; Moraes da Gama, E Int J Min Geol Engng V5, NJ, Ott 1987, P331-342 Coals from the Lorraine basin, France, and from south Brazil were studied to determine parameters influencing mechanical behaviour. Differences can be explained by contrasting compositions of vitrain, clairain, durain, and fusain. The French coal is elastobrittle or elastoplastic with progressive failure. The Brazilian coal is elastoplastic with progressive failure or perfectly etastoplastic. 0
886053 Initiation of soil liquefaction under static loading conditions Kramer, S L; Seed, H B J Geotech Engng Div ASCE V114, N4, April 1988, P412-430 Static liquefaction, resulting from the application of non-cyclic shear stress, has received little attention. A series of laboratory tests is presented in which 2 sands are analysed under various relative densities, confining pressures and initial stress conditions. Static liquefaction resistance, the shear stress under undrained conditions required to initiate liquefaction, was seen to increase with increased relative density and confining pressure and to decrease with increased initial shear stress level. The distinction between initiation and effect of liquefaction is discussed.
Strength parameters for bearing capacity of sand: technical note Kutter, B L; Abghari, A; Cheney, J A J Georech Engng Div ASCE V114, N4, April 1988, P491-498 Centrifuge and triaxial test results on concentric loading of circular footings on dense sand are presented and used to test the validity of methods to determine the friction angle for bearing capacity calculations. Also, an alternative procedure to approximate the failure envelope is proposed. The results are applicable to circular foundations where general shear failure is the dominant mechanism and punching shear does not occur. The centrifuge is shown to be a useful tool for bearing capacity tests and agreement from modelling of model tests supports centrifuge scaling laws.
1988 Pergamon Press plc. Reproduction
not permitted
Influence of stress-release disturbance, storage, and reconsolidation procedures on the shear hehaviour of reconstituted underwater clay Graham, J; Lau, S L K Georechnique V38, N2, June 1988, P279-300 Changes in undrained shear strength, pore pressure, and compressibility due to sampling, offloading, storage, and reconsolidation have been examined. Samples of normally and overconsolidated illite clays were prepared by anisotropic consolidation and tested immediately and after unloading, storage in the drained or undrained state, and reconsolidation by various procedures. Results varied considerably. Suitable practices for valid and consistent results are discussed.
To overcome frictional effects in a large scale plane strain apparatus. Technical note Matthews, R S; Boot, J C Geotechnique V38, N2, June 1988, P311-315 An economic low friction layer to minimise boundary shear stress in a 3mx3mx0.225m plane strain laboratory testing machine is described. The soil is confined between layers of foam rubber, and overlapping polythene tiles and glass ballotini are between this and the steel plates of the apparatus. Soil/container friction coefficient is maintained at 0.03-o. 10 for a wide range of stresses.
Experimental study of the elasticity of mylonite rock with random cracks Oda, M Inr J Rock Mech Min Sci V25, N2, April 1988, P59-69 An elastic compliance tensor for discontinuous rock masses has been formulated by treating each crack with an elastic equivalent, a set of parallel plates connected by 2 springs. Uniaxial compressive tests on 8 mylonite samples with various crack geometries were used to verify the theory. The results indicate that samples with different crack geometries can be compared generally with the help of crack tensor theory, the spring model is an acceptable idealization of elastic deformation of cracks if hysteresis of springs is taken into account, and that local strain is variable, but mean strain can be related to overall crack tensor.
886052 Siulatioa of borehole breakouts in a model material: technical note Perie, P J; Goodman, R E; Doe, T J Int J Rock Mech Min Sci V25, N2, April 1988, P97-98 A method to observe the progression of failure around a hole, using a bag of flour and a length of metal tubing, is presented. After ‘drilling’ the hole, failure is induced by squeezing the bag, creating a deviatoric horizontal stress, until breakout. Breakout appears in the direction of minimum squeezing, confirming a relation widely held with regard to rocks.
Engineering application of direct and simple shear testing Matthews, M C Ground Engng VZI, N2, March 1988, P13-21 The development of shear testing methods is described. The advantages and disadvantages of direct shear box tests, ring shear tests, simple shear tests and interface shear testing are discussed. Direct and simple testing are seen to offer greater similitude with the field prototype than triaxial tests, although uncertainty over non-uniform conditions means triaxial tests are the industry standard. 42 refs. 886049 Resistance of coal at temperature to direct shear (In French) Luong, M P; Schmitt, N h&she Minerale V69, NlO, Dee 1987. P390-392 A direct shear test was used to measure simple compression and shear behaviour of heterogeneous, anisotropic coal samples over a range of temperatures. Results indicate that cohesion decreases as the temperature rises, and decreases more rapidly than resistance to compression. At 750 deg C the material has lost 75% of its cohesion. The tests were part of a series to determine different points of the intrinsic fracture curve.
Petrography, structure and mechanical behaviour of coals Homand-Etienne, F; Moraes da Gama, E Int J Min Geol Engng V5, NJ, Ott 1987, P331-342 Coals from the Lorraine basin, France, and from south Brazil were studied to determine parameters influencing mechanical behaviour. Differences can be explained by contrasting compositions of vitrain, clairain, durain, and fusain. The French coal is elastobrittle or elastoplastic with progressive failure. The Brazilian coal is elastoplastic with progressive failure or perfectly etastoplastic. 0
886053 Initiation of soil liquefaction under static loading conditions Kramer, S L; Seed, H B J Geotech Engng Div ASCE V114, N4, April 1988, P412-430 Static liquefaction, resulting from the application of non-cyclic shear stress, has received little attention. A series of laboratory tests is presented in which 2 sands are analysed under various relative densities, confining pressures and initial stress conditions. Static liquefaction resistance, the shear stress under undrained conditions required to initiate liquefaction, was seen to increase with increased relative density and confining pressure and to decrease with increased initial shear stress level. The distinction between initiation and effect of liquefaction is discussed.
Strength parameters for bearing capacity of sand: technical note Kutter, B L; Abghari, A; Cheney, J A J Georech Engng Div ASCE V114, N4, April 1988, P491-498 Centrifuge and triaxial test results on concentric loading of circular footings on dense sand are presented and used to test the validity of methods to determine the friction angle for bearing capacity calculations. Also, an alternative procedure to approximate the failure envelope is proposed. The results are applicable to circular foundations where general shear failure is the dominant mechanism and punching shear does not occur. The centrifuge is shown to be a useful tool for bearing capacity tests and agreement from modelling of model tests supports centrifuge scaling laws.
1988 Pergamon Press plc. Reproduction
not permitted