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Undrained strength of sand undergoing cyclic rotation of principal stress axes
7A
861047 Anisotropy of undrained shear strength of clays under axisymmetric loading conditions Ohta, H; Nishihara, A Soils Found V25, N2, June 1985, P73-86 An understanding of the anisotropy of undrained shear strength of clays is necessary in soil mechanics. The anisotropy of shear strength is formulated assuming that anisotropy is induced by the initial anisotropic stress state. Using the constitutive equation of Sekiguchi and Ohta (1977), equations can be derived to describe the undrained state and the failure state. These are applied to the axi-symmetric stress state and used to predict values of undrained shear strength for normally and overconsolidated clays on triaxial testing. Results are compared with theoretical and measured strengths previously reported.
861048 Undrained strength of sand undergoing cyclic rotation of principal stress axes Towhata, I; Ishihara, K Soils Found V25, N2, June 1985, P135-147 Cyclic tests were carried out on saturated samples of Toyoura sand, using a triaxial torsional shear apparatus, where a hollow cylindrical specimen is simultaneously subjected to triaxial and torsional stresses, which brings about the continuous rotation of principal stress axes. This led to volume change in drained specimens and pore pressure rise in undrained tests. Liquefaction resistance was reduced by around 8% by continuous rotation of the principal stress axes, although friction angle was not affected. The effect of previous liquefaction on the undrained behaviour of sand on cyclic loading was also examined.
861049 Stress-strain behaviour of jointed rock masses Brown, E T Proc 6th National Rock Mechanics Symposium, Aachen, 3-4 April 1985 P13-20. Publ Essen: German Society for Soil Mechanics and Foundation Engineering, 1985 Direct and indirect methods of studying the stress-strain behaviour of jointed rock masses are briefly reviewed. The major differences between stress-strain properties of intact and jointed rocks are identified from the results of large scale laboratory tests and multi-axial in-situ tests. The post-yield behaviour of jointed rock masses, and the use of the incremental theory of plasticity for its modelling, are examined, and a yield criterion which can be applied in some cases is developed. The difficulties arising from heterogeneity, strain softening and localised deformation are highlighted. 38 refs.
861050 Effect of filler composition on the mechanical behaviour of filled rock joints (In German) Howing, K D; Kuttcr, H K Proc 6th National Rock Mechanics Symposium, Aachen, 3-4 April 1985 P21-26. Publ Essen: German Society for Soil Mechanics and Foundation Engineering, 1985 Properties of discontinuous rock masses are determined by joint patterns and nature, in particular surface roughness and the filler material. Laboratory shear tests have been carried out on filled rock discontinuities, single rock-filler contact planes and on the filler material itself. Results show that unless there is contact between asperities on the joint surfaces, shear strength is determined by the properties of the filler material. A direct relationship can be established between the clay mineral fraction of the filling, shear strength and permeability of the joint.
861051 Mechanical properties of American (Penn Argyl) slate Bhadada, ft. Proc 6th National Rock Mechanics Symposium, Aachen, 3-4 April 1985 P27-32. Publ Essen: German Society for Soil Mechanics and Foundation Engineering, 1985 The stress-strain behaviour, elastic and mechanical properties of Penn Argyl slate have been studied by uniaxiai tensile and compressive testing and flexural tests. Anisotropy of properties and the effect of immersion in water have been examined with a view to assessing the suitability of this material for structural use.
861052 Field observation of pore pressure in soft clay Wei, R L Proc International Conference on Case Histories in Geoteehnical Engineering, Rolla, Missouri, 6-11 May 1984 V1, P179-183. Publ St Louis: Geotechnical Engineering, 1984 Pore pressure measurements made during the preloading of a large oil tank on a deep deposit of soft clay are reported and analyzed. The piezometer data show that the excess pore pressure in the subsoil increases linearly with increasing surface load, until a certain critical load is reached. At that point, when induced shear stress exceeds soil shear strength, local yield occurs. Once yield has occurred, the rate of pore pressure build up increases markedly.
861053 Power line foundation design using the pressuremeter Briaud, J L; Pacal, A J; Shively, A W Proc International Conference on Case Histories in Geotechnieal Engineering, RoUa, Missouri, 6-11 May 1984 V1, P279-283. Publ St Louis: Geotechnical Engineering, 1984 During the design phase of a 2000-towers electric power transmission line,a load test programme was undertaken to evaluate the accuracy of new design methods for uplift and lateral capacity of drilled shafts. Seven uplift tests and six lateral load tests were performed in three different soil deposits, a medium clay, a very hard clay and a sand. Soil properties including pressuremeter and cone penetrometer test results are given for each site. The behaviour predictions based on pressuremeter design methods are shown. The load test programme and results are presented, and the predicted and measured behaviour of the shafts are compared.
861054 Study of the plasticity of lateritic soils: methodology and effect of drying on liquid and plastic limits Carvalho, J B Q Proc 1st International Conference on Geomechanics in Tropical Lateritic and Suprolitic Soils, Brasilia, 11-14 February 1985 V1, P63-76. Publ Sao Paulo: Brazilian SocieO' for Soil Mechanics, 1985 Liquid and plastic limits were measured for nine lateritic soils from north east Brazil after air drying at room temperature and oven drying at 60 and 105 dog C. The Casagrande apparatus was used to measure liquid limit and the rolled thread technique to measure plastic limit. Statistical analysis of the results showed the methods were suitable for lateritic soils. Predrying slightly reduced the liquid limit of some soils and slightly raised the plastic limit. These changes were statistically significant, but were not so from the engineering viewpoint.
861047 Anisotropy of undrained shear strength of clays under axisymmetric loading conditions Ohta, H; Nishihara, A Soils Found V25, N2, June 1985, P73-86 An understanding of the anisotropy of undrained shear strength of clays is necessary in soil mechanics. The anisotropy of shear strength is formulated assuming that anisotropy is induced by the initial anisotropic stress state. Using the constitutive equation of Sekiguchi and Ohta (1977), equations can be derived to describe the undrained state and the failure state. These are applied to the axi-symmetric stress state and used to predict values of undrained shear strength for normally and overconsolidated clays on triaxial testing. Results are compared with theoretical and measured strengths previously reported.
861048 Undrained strength of sand undergoing cyclic rotation of principal stress axes Towhata, I; Ishihara, K Soils Found V25, N2, June 1985, P135-147 Cyclic tests were carried out on saturated samples of Toyoura sand, using a triaxial torsional shear apparatus, where a hollow cylindrical specimen is simultaneously subjected to triaxial and torsional stresses, which brings about the continuous rotation of principal stress axes. This led to volume change in drained specimens and pore pressure rise in undrained tests. Liquefaction resistance was reduced by around 8% by continuous rotation of the principal stress axes, although friction angle was not affected. The effect of previous liquefaction on the undrained behaviour of sand on cyclic loading was also examined.
861049 Stress-strain behaviour of jointed rock masses Brown, E T Proc 6th National Rock Mechanics Symposium, Aachen, 3-4 April 1985 P13-20. Publ Essen: German Society for Soil Mechanics and Foundation Engineering, 1985 Direct and indirect methods of studying the stress-strain behaviour of jointed rock masses are briefly reviewed. The major differences between stress-strain properties of intact and jointed rocks are identified from the results of large scale laboratory tests and multi-axial in-situ tests. The post-yield behaviour of jointed rock masses, and the use of the incremental theory of plasticity for its modelling, are examined, and a yield criterion which can be applied in some cases is developed. The difficulties arising from heterogeneity, strain softening and localised deformation are highlighted. 38 refs.
861050 Effect of filler composition on the mechanical behaviour of filled rock joints (In German) Howing, K D; Kuttcr, H K Proc 6th National Rock Mechanics Symposium, Aachen, 3-4 April 1985 P21-26. Publ Essen: German Society for Soil Mechanics and Foundation Engineering, 1985 Properties of discontinuous rock masses are determined by joint patterns and nature, in particular surface roughness and the filler material. Laboratory shear tests have been carried out on filled rock discontinuities, single rock-filler contact planes and on the filler material itself. Results show that unless there is contact between asperities on the joint surfaces, shear strength is determined by the properties of the filler material. A direct relationship can be established between the clay mineral fraction of the filling, shear strength and permeability of the joint.
861051 Mechanical properties of American (Penn Argyl) slate Bhadada, ft. Proc 6th National Rock Mechanics Symposium, Aachen, 3-4 April 1985 P27-32. Publ Essen: German Society for Soil Mechanics and Foundation Engineering, 1985 The stress-strain behaviour, elastic and mechanical properties of Penn Argyl slate have been studied by uniaxiai tensile and compressive testing and flexural tests. Anisotropy of properties and the effect of immersion in water have been examined with a view to assessing the suitability of this material for structural use.
861052 Field observation of pore pressure in soft clay Wei, R L Proc International Conference on Case Histories in Geoteehnical Engineering, Rolla, Missouri, 6-11 May 1984 V1, P179-183. Publ St Louis: Geotechnical Engineering, 1984 Pore pressure measurements made during the preloading of a large oil tank on a deep deposit of soft clay are reported and analyzed. The piezometer data show that the excess pore pressure in the subsoil increases linearly with increasing surface load, until a certain critical load is reached. At that point, when induced shear stress exceeds soil shear strength, local yield occurs. Once yield has occurred, the rate of pore pressure build up increases markedly.
861053 Power line foundation design using the pressuremeter Briaud, J L; Pacal, A J; Shively, A W Proc International Conference on Case Histories in Geotechnieal Engineering, RoUa, Missouri, 6-11 May 1984 V1, P279-283. Publ St Louis: Geotechnical Engineering, 1984 During the design phase of a 2000-towers electric power transmission line,a load test programme was undertaken to evaluate the accuracy of new design methods for uplift and lateral capacity of drilled shafts. Seven uplift tests and six lateral load tests were performed in three different soil deposits, a medium clay, a very hard clay and a sand. Soil properties including pressuremeter and cone penetrometer test results are given for each site. The behaviour predictions based on pressuremeter design methods are shown. The load test programme and results are presented, and the predicted and measured behaviour of the shafts are compared.
861054 Study of the plasticity of lateritic soils: methodology and effect of drying on liquid and plastic limits Carvalho, J B Q Proc 1st International Conference on Geomechanics in Tropical Lateritic and Suprolitic Soils, Brasilia, 11-14 February 1985 V1, P63-76. Publ Sao Paulo: Brazilian SocieO' for Soil Mechanics, 1985 Liquid and plastic limits were measured for nine lateritic soils from north east Brazil after air drying at room temperature and oven drying at 60 and 105 dog C. The Casagrande apparatus was used to measure liquid limit and the rolled thread technique to measure plastic limit. Statistical analysis of the results showed the methods were suitable for lateritic soils. Predrying slightly reduced the liquid limit of some soils and slightly raised the plastic limit. These changes were statistically significant, but were not so from the engineering viewpoint.