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Natural joints in rock: mechanical, hydraulic and seismic behaviour and properties under normal stress
344A 926036 Shear modulus of cohesionless soil: variation with stress and strain level. Note Fahey, M Can Geotech J 1/29, N1, Feb 1992, P157-161 Based on the assumption of a hyperbolic stress strain curve and the relations of confining pressure to shear strength and maximum shear modulus from cyclic loading tests, it is shown that reduction of shear modulus with shear strain for cohesionless soils is dependent on confining stress. It is also demonstrated that plotting normalised shear modulus against normalised shear stress level, rather than normalised shear strain level, may be a more logical and unifying method of comparing shear moduli from different tests.
926037 Collapse and strength characteristics of loess in Thailand Phien-wej, N; Pientong, T; Balasubramaniam, A S Engng Geol V32, N1/2, Feb 1992. P59-72 Collapse and strength properties of the loess soils widely deposited over NE Thailand have been investigated. Field plate bearing tests and laboratory double oedometer and triaxial compression tests were used. Collapsibility is strongly affected by water content and applied stress. Variation of collapse pressure with water content was examined. At a given applied stress, final porosity arrived at was effectively independent of initial water content. Shear strength was influenced by initial water content, consolidation pressure, and drainage conditions.
926038 Bromhead ring shear test procedure Stark, T D; Vettel, J J Geotech Test J VI5, NI, March 1992, P24-32 Existing test procedures and a proposed modification for the Bromhead ring shear apparatus are described. These yield drained residual strengths in excess of those back-calculated from field case histories. The proposed modification involves limiting the settlement of the top porous stone, resulting from consolidation or soil extrusion, to 0.75ram. This minimises the wall friction (the main factor affecting measured residual strength) developed along the inner and outer circumferences of the specimen. This procedure gives residual strength values closest to back-calculations.
926039 Natural joints in rock: mechanical, hydraulic and seismic behaviour and properties under normal stress Cook, N G W Int J Rock Mech Min Sci 1/29, N3, May 1992, P198-223 The Jaeger Memorial Dedication Lecture. A comprehensive summary is presented of how engineering properties and wave propagation for a rock mass are affected by the presence of joints. Mechanical deformation of joints and how it is influenced by stress state and loading pattern are first examined. Fluid flow through joints and the importance of joint topography and stress regime are discussed. The way in which joints interact with incident seismic waves and its relevance to geophysical detection of rock mass discontinuities are analysed. Throughout, a sound theoretical basis is presented, supplemented by experimental details and bibliography. 50 refs.
926040 Modelling of rock joints under shear and normal loading Saeb, S; Amadei, B lnt J Rock Mech Min Sci 1/29, N3, May 1992, P267-27~ Response of a dilatant joint to shear loading depends on both the boundary conditions applied across its surfaces and joint surface properties. A model relating the normal load-deformation response of a joint to its shear load-deformation and dilatant behaviour is presented. It is given in graphical and analytical forms. Normal deformability of an initially mated joint as it traverses unmated conditions is examined. The ability of the model to describe behaviour of a rock joint under applied constant normal stiffness boundary conditions is confirmed by comparing its predictions to experimental data. 926041 Strength correlation factor for residual soils Loganathan, N; de Silva, S; Thurairajah, A J Geotech Engng Div A S C E VlI8, N4, April 1992, P593-610 The residual soils covering most of the land area of Sri Lanka are heterogeneous, and strength parameters from small samples are not representative of the soil mass. Actual field shear parameters can be obtained from back analysis of failed slopcs and used to establish correlation factors between laboratory shear strengths and field values. These correction factors can then be used to modify other laboratory shear parameters for design purposes. 926042 Effective cohesion for compacted clay Day, R W J Geotech Engng Div A S C E VIIS, 1¥4, April 1992, P611-619 Unsupported compacted clay samples will generally completely slake apart in water, but if they have been compacted over optimum and allowed to cure, this may not happen. The unsupported sample has a zero horizontal total stress field and if sheared slowly enough to allow dissipation of negative pore pressure, the effective cohesion can be determined. Effective cohesion of compacted clay was measured at 0.4kPa after l day curing to 2.2kPa after 21 days. During curing, bonds develop, resulting in reduced swelling and higher effective cohesion. Drained direct shear tests show a nonlinear strength envelope, dropping beneath the linear part at low normal stresses and giving a low effective cohesion intercept. 926043 Generalized state parameter for partly saturated soils. Technical note Pandian, N S; Nagara), T S; Babu, G L S K J Geotech Engng Div A S C E VI18, N4. April 1992, P622-627 Soils in tropical regions are often in a state of partial saturation. which can lead to engineering problems. Generaliscd state parameters for these soils have been investigated, and one relation proposed links the product of void ratio and square root of degree of saturation to logarithm of shear strength. Laboratory shear and compressibility tests on three tropical soils with different liquid limits are used to demonstrate the validity of the proposed relation and to evaluate its constants. 926044 Development of strain during monotonic shear of soft clay Frydman, S; Talesnick, M J Geotech Engng Div A S C E Vl18, N5, May 1992, P704-725 Torsional and simple shear tests were carried out on a soft marine clay. The ratio of plastic shear strain to overall shear strain on a particular plane was related to that overall strain
if~ 1992 Pergamon Press Ltd. Reproduction not permitted
926037 Collapse and strength characteristics of loess in Thailand Phien-wej, N; Pientong, T; Balasubramaniam, A S Engng Geol V32, N1/2, Feb 1992. P59-72 Collapse and strength properties of the loess soils widely deposited over NE Thailand have been investigated. Field plate bearing tests and laboratory double oedometer and triaxial compression tests were used. Collapsibility is strongly affected by water content and applied stress. Variation of collapse pressure with water content was examined. At a given applied stress, final porosity arrived at was effectively independent of initial water content. Shear strength was influenced by initial water content, consolidation pressure, and drainage conditions.
926038 Bromhead ring shear test procedure Stark, T D; Vettel, J J Geotech Test J VI5, NI, March 1992, P24-32 Existing test procedures and a proposed modification for the Bromhead ring shear apparatus are described. These yield drained residual strengths in excess of those back-calculated from field case histories. The proposed modification involves limiting the settlement of the top porous stone, resulting from consolidation or soil extrusion, to 0.75ram. This minimises the wall friction (the main factor affecting measured residual strength) developed along the inner and outer circumferences of the specimen. This procedure gives residual strength values closest to back-calculations.
926039 Natural joints in rock: mechanical, hydraulic and seismic behaviour and properties under normal stress Cook, N G W Int J Rock Mech Min Sci 1/29, N3, May 1992, P198-223 The Jaeger Memorial Dedication Lecture. A comprehensive summary is presented of how engineering properties and wave propagation for a rock mass are affected by the presence of joints. Mechanical deformation of joints and how it is influenced by stress state and loading pattern are first examined. Fluid flow through joints and the importance of joint topography and stress regime are discussed. The way in which joints interact with incident seismic waves and its relevance to geophysical detection of rock mass discontinuities are analysed. Throughout, a sound theoretical basis is presented, supplemented by experimental details and bibliography. 50 refs.
926040 Modelling of rock joints under shear and normal loading Saeb, S; Amadei, B lnt J Rock Mech Min Sci 1/29, N3, May 1992, P267-27~ Response of a dilatant joint to shear loading depends on both the boundary conditions applied across its surfaces and joint surface properties. A model relating the normal load-deformation response of a joint to its shear load-deformation and dilatant behaviour is presented. It is given in graphical and analytical forms. Normal deformability of an initially mated joint as it traverses unmated conditions is examined. The ability of the model to describe behaviour of a rock joint under applied constant normal stiffness boundary conditions is confirmed by comparing its predictions to experimental data. 926041 Strength correlation factor for residual soils Loganathan, N; de Silva, S; Thurairajah, A J Geotech Engng Div A S C E VlI8, N4, April 1992, P593-610 The residual soils covering most of the land area of Sri Lanka are heterogeneous, and strength parameters from small samples are not representative of the soil mass. Actual field shear parameters can be obtained from back analysis of failed slopcs and used to establish correlation factors between laboratory shear strengths and field values. These correction factors can then be used to modify other laboratory shear parameters for design purposes. 926042 Effective cohesion for compacted clay Day, R W J Geotech Engng Div A S C E VIIS, 1¥4, April 1992, P611-619 Unsupported compacted clay samples will generally completely slake apart in water, but if they have been compacted over optimum and allowed to cure, this may not happen. The unsupported sample has a zero horizontal total stress field and if sheared slowly enough to allow dissipation of negative pore pressure, the effective cohesion can be determined. Effective cohesion of compacted clay was measured at 0.4kPa after l day curing to 2.2kPa after 21 days. During curing, bonds develop, resulting in reduced swelling and higher effective cohesion. Drained direct shear tests show a nonlinear strength envelope, dropping beneath the linear part at low normal stresses and giving a low effective cohesion intercept. 926043 Generalized state parameter for partly saturated soils. Technical note Pandian, N S; Nagara), T S; Babu, G L S K J Geotech Engng Div A S C E VI18, N4. April 1992, P622-627 Soils in tropical regions are often in a state of partial saturation. which can lead to engineering problems. Generaliscd state parameters for these soils have been investigated, and one relation proposed links the product of void ratio and square root of degree of saturation to logarithm of shear strength. Laboratory shear and compressibility tests on three tropical soils with different liquid limits are used to demonstrate the validity of the proposed relation and to evaluate its constants. 926044 Development of strain during monotonic shear of soft clay Frydman, S; Talesnick, M J Geotech Engng Div A S C E Vl18, N5, May 1992, P704-725 Torsional and simple shear tests were carried out on a soft marine clay. The ratio of plastic shear strain to overall shear strain on a particular plane was related to that overall strain
if~ 1992 Pergamon Press Ltd. Reproduction not permitted