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Instability of granular soils under strain path testing
340A
936055 Determination of discontinuity wall strength by Equotip and ball rebound tests. Technical note Hack, H R G K; Hingira, J; Verwaal, W Int J Rock Mech Min Sci V30, N2, April 1993, P151-155 In rebound tests, measurements are influenced by characteristics of the immediate surface and the subsurface. The standard Schmidt hammer releases so much energy that the layer of influence can be up to centimetres thick. Two rebound devices of much lower impact energy, ball rebound and Equotip instruments, have been evaluated on granite, limestone, and sandstone samples. Correlations between results of the tests and with other rock properties are discussed. Influence of depth in these tests and calculating discontinuity wall strength are examined.
936056 Observations on the measurement of tensile strength using the hoop test. Technical note Butenuth, C; de Freitas, M H; AI-Samahiji, D; Park, H D; Cosgrove, J W; Schetelig, K Int J Rock Mech Min Sci V30, N2, April 1993, P157-162 The hoop test, in which a ring specimen is loaded using a pair of half-cylindrical platens resting on the inner surface of the short hollow cylinder, has many operational advantages over the conventional direct tensile test. Results from these two tests are compared for saturated and oven dried specimens of sandstones and marble. Strengths obtained are generally in excellent agreement, confirming the acceptability of this practical test technique.
936057 Municipal solid-waste incinerator fly ash for geotechnical applications Goh, A T C; Tay, J H J Geotech Engng Div ASCE Vl19, N5, May 1993, P811-825 Incineration of municipal waste and constructive use of the fly ash is an economic alternative to simple landfill disposal. Incinerator fly ash is shown to be a potential source of low density, high strength fill, with permeability similar to that of coarse granular materials. Fly ash additions improve shear strength and compressibility of soft marine clays. Leachate tests on fly ash samples show initial levels of Cd and Cr above drinking water limits, but they are within limits after 28 days leaching. When the fly ash was stabilised with lime and cement, heavy metals were undetectable in leachates.
936058 Tropical clays. I: Index properties and microstructural aspects Pandian, N S; Nagaraj, T S; Babu, G L S J Geotech Engng Div ASCE Vl19, NS, May 1993, P826-839 Soils showing changes in plasticity characteristics due to drying form an important group in tropical soils. Atterberg limits, grain size distribution patterns, relations between liquid limit and plasticity index, and permeability at liquid limit were examined for several tropical clays at different natural and forced states of drying. Changes can be attributed to grouping of particles into aggregates either due to mineralogy or presence of cementing agents and/or pore fluid characteristics. The changes are irreversible. Permeability is an indirect indicator of microstructure, depending on pore geometry.
936059 Tropical clays. II: Engineering behaviour Pandian, N S; Nagaraj, T S; Babu, G L S J Geotech Engng Div ASCE V119, N5, May 1993. P840-861 Many tropical residual clays show changes in plasticity characteristics on drying. For these soils it is generally assumed that compressibility decreases with drying, whilst shear strength and permeability increase. These suppositions have been examined within the framework of the generalised state parameter approach. Drying leads to reduction in overall potential represented by liquid limit, and reduction in void ratio for equilibrium under a given load, such that the same pore structure exists when equilibrium conditions are reached. Permeability coefficients do not increase with drying under a given load, but settlement occurs. Shear strength also does not increase with drying.
936060 Instability of granular soils under strain path testing Chu, J; Lo, S C R; Lee, I K J Geotech Engng Div ASCE Vl19, N5, May 1993, P874-892 Prefailure instability (runaway instability prior to attaining the failure stress state) has been observed in laboratory tests on loose sands. Strain path tests with a constant strain-incrementratio path were carried out to study this behaviour under more general conditions in medium-loose to dense sands. Prefailure instability can occur for dense sands under certain conditions of initial void ratio, effective stress ratio, and strain increment ratio. Accurate prediction of occurrence of prefailure instability is possible. 936O61 Undrained cyclic loading of anisotropically consolidated clayey silts Konrad, J M; Wagg, B J J Geoteeh Engng Div ASCE 11119, N5, May 1993, P929-947 Test data are presented for specimens of a pure silica silt containing 0-40% kaolin clay subject to anisotropic cyclic loads without shear stress reversal. Behaviour can be adequately described in terms of average resultant cyclic strain rate, a constant rate of deformation reached after several loading cycles. This strain rate is shown to depend on imposed static shear stress, cyclic stress ratio, and clay content. Nonuniform pore pressure effects are related to the average resultant cyclic strain rate whilst dynamic strength parameters are related to the maximum cyclic strain rate.
936062 Index properties and physico-mechanicai properties of coal and coal measures rocks vis-a-vis fracture toughness Ghose, A K; Biswas, K J Min Metal Fuels V40, N10/11, Oct-Nov 1992. P295-300 Fracture mechanics parameters of rocks are primary controlling factors governing the failure process. To avoid repeated measurements of these parameters, correlations have been established between fracture toughness of Indian coals and coal measures sandstones and the easily determined UCS, Brazilian tensile strength, point load index, and NCB cone indentation index. Reliable and repeatable results are obtained.
936063 Elementary geometry of deformation processes Means, W D J Struct Geol V15, N3-5, March-May 1993, P343-349 All rock transformations are ultimately structural in nature with particle movement and alteration in the arrangement or intensity of structural elements. In order to help understand
© 1993 Pergamon Press Ltd. Reproduction not permitted
936055 Determination of discontinuity wall strength by Equotip and ball rebound tests. Technical note Hack, H R G K; Hingira, J; Verwaal, W Int J Rock Mech Min Sci V30, N2, April 1993, P151-155 In rebound tests, measurements are influenced by characteristics of the immediate surface and the subsurface. The standard Schmidt hammer releases so much energy that the layer of influence can be up to centimetres thick. Two rebound devices of much lower impact energy, ball rebound and Equotip instruments, have been evaluated on granite, limestone, and sandstone samples. Correlations between results of the tests and with other rock properties are discussed. Influence of depth in these tests and calculating discontinuity wall strength are examined.
936056 Observations on the measurement of tensile strength using the hoop test. Technical note Butenuth, C; de Freitas, M H; AI-Samahiji, D; Park, H D; Cosgrove, J W; Schetelig, K Int J Rock Mech Min Sci V30, N2, April 1993, P157-162 The hoop test, in which a ring specimen is loaded using a pair of half-cylindrical platens resting on the inner surface of the short hollow cylinder, has many operational advantages over the conventional direct tensile test. Results from these two tests are compared for saturated and oven dried specimens of sandstones and marble. Strengths obtained are generally in excellent agreement, confirming the acceptability of this practical test technique.
936057 Municipal solid-waste incinerator fly ash for geotechnical applications Goh, A T C; Tay, J H J Geotech Engng Div ASCE Vl19, N5, May 1993, P811-825 Incineration of municipal waste and constructive use of the fly ash is an economic alternative to simple landfill disposal. Incinerator fly ash is shown to be a potential source of low density, high strength fill, with permeability similar to that of coarse granular materials. Fly ash additions improve shear strength and compressibility of soft marine clays. Leachate tests on fly ash samples show initial levels of Cd and Cr above drinking water limits, but they are within limits after 28 days leaching. When the fly ash was stabilised with lime and cement, heavy metals were undetectable in leachates.
936058 Tropical clays. I: Index properties and microstructural aspects Pandian, N S; Nagaraj, T S; Babu, G L S J Geotech Engng Div ASCE Vl19, NS, May 1993, P826-839 Soils showing changes in plasticity characteristics due to drying form an important group in tropical soils. Atterberg limits, grain size distribution patterns, relations between liquid limit and plasticity index, and permeability at liquid limit were examined for several tropical clays at different natural and forced states of drying. Changes can be attributed to grouping of particles into aggregates either due to mineralogy or presence of cementing agents and/or pore fluid characteristics. The changes are irreversible. Permeability is an indirect indicator of microstructure, depending on pore geometry.
936059 Tropical clays. II: Engineering behaviour Pandian, N S; Nagaraj, T S; Babu, G L S J Geotech Engng Div ASCE V119, N5, May 1993. P840-861 Many tropical residual clays show changes in plasticity characteristics on drying. For these soils it is generally assumed that compressibility decreases with drying, whilst shear strength and permeability increase. These suppositions have been examined within the framework of the generalised state parameter approach. Drying leads to reduction in overall potential represented by liquid limit, and reduction in void ratio for equilibrium under a given load, such that the same pore structure exists when equilibrium conditions are reached. Permeability coefficients do not increase with drying under a given load, but settlement occurs. Shear strength also does not increase with drying.
936060 Instability of granular soils under strain path testing Chu, J; Lo, S C R; Lee, I K J Geotech Engng Div ASCE Vl19, N5, May 1993, P874-892 Prefailure instability (runaway instability prior to attaining the failure stress state) has been observed in laboratory tests on loose sands. Strain path tests with a constant strain-incrementratio path were carried out to study this behaviour under more general conditions in medium-loose to dense sands. Prefailure instability can occur for dense sands under certain conditions of initial void ratio, effective stress ratio, and strain increment ratio. Accurate prediction of occurrence of prefailure instability is possible. 936O61 Undrained cyclic loading of anisotropically consolidated clayey silts Konrad, J M; Wagg, B J J Geoteeh Engng Div ASCE 11119, N5, May 1993, P929-947 Test data are presented for specimens of a pure silica silt containing 0-40% kaolin clay subject to anisotropic cyclic loads without shear stress reversal. Behaviour can be adequately described in terms of average resultant cyclic strain rate, a constant rate of deformation reached after several loading cycles. This strain rate is shown to depend on imposed static shear stress, cyclic stress ratio, and clay content. Nonuniform pore pressure effects are related to the average resultant cyclic strain rate whilst dynamic strength parameters are related to the maximum cyclic strain rate.
936062 Index properties and physico-mechanicai properties of coal and coal measures rocks vis-a-vis fracture toughness Ghose, A K; Biswas, K J Min Metal Fuels V40, N10/11, Oct-Nov 1992. P295-300 Fracture mechanics parameters of rocks are primary controlling factors governing the failure process. To avoid repeated measurements of these parameters, correlations have been established between fracture toughness of Indian coals and coal measures sandstones and the easily determined UCS, Brazilian tensile strength, point load index, and NCB cone indentation index. Reliable and repeatable results are obtained.
936063 Elementary geometry of deformation processes Means, W D J Struct Geol V15, N3-5, March-May 1993, P343-349 All rock transformations are ultimately structural in nature with particle movement and alteration in the arrangement or intensity of structural elements. In order to help understand
© 1993 Pergamon Press Ltd. Reproduction not permitted