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Strength of intact geomechanical materials
6A
861039 Expanded shale lightweight fill: geotechnicai properties. Technical note Stoll, R D. Holm, T A J Geotech Engng Div A S C E V I l I . NS, Aug 1985, P10231027 Triaxial tests were carried out on six different samples of lightweight expanded aggregate using both loose and compacted specimens. One sample was subjected to consolidation testing and triaxial testing at different confining pressures and in the soaked condition. Properties were seen to be similar to many ordinary coarse fill materials, and may be used where the weight saving justifies the extra costs. Although there were differences between the six materials sampled, properties were uniform within each sample.
861040 Lateral stresses observed in two simple shear apparatus Budhu, M J Geotech Engng Div A S C E Vl11, N6, June 1985, P698-711 Two simple shear apparatus (SSA), the Cambridge University SSA Mk7 and an NGI type, were used to compare the radial stresses developed in the NGI-type SSA with the horizontal normal stresses on the plane perpendicular to the plane of shear deformation and the intermediate principal effective stresses as measured in the Cambridge University SSA Mk7. These stresses are often assumed to be equal. Monotonic and cyclic simple shear tests were conducted on dense and loose Leighton Buzzard sand at constant applied vertical load. Comparison of results shows that the radial stresses are equal to neither the horizontal normal stresses nor the intermediate principal effective stress ratio and the horizontal stress ratio reached at peak stress ratio (maximum shear stress/vertical) in monotonic tests on sand in its initial densest state represent threshold values for cyclic simple shear tests. Auth.
861041 Bearing capacity of gravity bases on layered soil Georgiadis, M; Michalopoulos, A P d Geotech Engng Div A S C E V I I I , N6, June 1985. P712-729 A simple numerical method for evaluating the bearing capacity of shallow foundations on layered soil is presented. Several potential failure surfaces are analyzed and the minimum material factor for which the foundation is stable is determined. Comparisons between the results obtained with the new method, a number of semi-empirical solutions for uniform and two-layer systems, experiments and other numerical methods including finite elements provide a valuable assessment of the performance of the various methods currently used and demonstrate the validity of the new method. Auth.
861043 Cyclic loading and modeling of interfaces Desai, C S: Drumm. E C: Zaman, M M J Geotech Engng Dir A S C E 1"111, N6. June 19~5, P793-,~'15 A new device for cyclic testing of large size interfaces between structural and geologic materials and rock joints is described. Test results are reported for a sand-concrete interface, and arc used to express shear stress as function of normal stress, relative displacement, number of loading cycles and initial density. Constitutive behaviour of the interface is expressed as nonlinear elastic and simulates loading-unloading-reloading response by using a modified Ramberg-Osgood model. The parameters for the models are found from a series of cyclic displacement controlled tests. Predictions of the constitutive model and a finite element analysis arc compared with observed test behaviour. Auth.
861044 Creep, dilatancy and compressibility of rocks around pressure shafts and oil wells (In French) Cristescu, N Rev Fr Geotech N31, 1985. Pll-22 For oil well bores or pressure shafts, it is important to know whether the rock surrounding the bore is dilatant or compressible. An elasto-viscoplastic constitutive equation is proposed which can describe the compressibility and'or dilatancy of the rock. Stress and strain fields around the bore can be determined and creep and stress relaxation studied. The stress state, depth and pressure inside the well at which the rock around the well becomes dilatant, and thus absorbs the liquid present, can be determined. Using this model, possible methods of avoiding this rock dilatancy problem are discussed, and numerical examples are given for a hard rock and one less hard.
861045 Micromechanisms for plastic deformation of a granular soil (In French) Cambou, B Rev Fr Geotech N31, 1985, P39-51 A static analysis is proposed to examine the mechanisms of plastic deformation of a granular material and the factors controlling these mechanisms. Starting from first principles, a two-dimensional analysis is made of grains of equal size in an irregular array. The angular distribution of contact forces is used to identify and define two strain hardening mechanisms, one related to the mean contact force, the other to the range of values of contact forces. The model can explain many experimentally observed properties of granular materials.
861046 Mechanical properties and strength anisotropy of decomposed granite soil
861042 Strength of intact geomechanical materials
Onitsuka, K; Yoshitake, S; Nanri, M Soils Found 1/25, N2, June 1985, P14-30
Johnston, I W d Geotech Engng Div A S C E Vl11. N6, June 1985, P730-749
Direct shear tests have been carried out on undisturbed and compacted decomposed granite soils. Shear strength characteristics and the influence of soaking and compaction method were examined. Strength anisotropy was examined by direct shear tests on specimens with failure planes parallel to and perpendicular to the vertical. Compacted soil shows lower shear strength than undisturbed soil, and method of compaction also affects strength. Soaking weakens compacted soils more than undisturbed samples, which is explained in terms of apparent cohesion. A schematic soil structure is proposed to explain the behaviour.
The strength of geomechanical materials can be described by a number of strength criteria. However, each criterion is usually limited to certain material types with a limited range of stress conditions. A new empirical strength criterion is proposed and shown to apply to a wide range of intact materials, from lightly overconsolidated clays through hard rocks, for both compressive and tensile stress regions. It is demonstrated that the strengths of these widely differing materials follow a distinctive progressive pattern. Auth. 81 refs.
861039 Expanded shale lightweight fill: geotechnicai properties. Technical note Stoll, R D. Holm, T A J Geotech Engng Div A S C E V I l I . NS, Aug 1985, P10231027 Triaxial tests were carried out on six different samples of lightweight expanded aggregate using both loose and compacted specimens. One sample was subjected to consolidation testing and triaxial testing at different confining pressures and in the soaked condition. Properties were seen to be similar to many ordinary coarse fill materials, and may be used where the weight saving justifies the extra costs. Although there were differences between the six materials sampled, properties were uniform within each sample.
861040 Lateral stresses observed in two simple shear apparatus Budhu, M J Geotech Engng Div A S C E Vl11, N6, June 1985, P698-711 Two simple shear apparatus (SSA), the Cambridge University SSA Mk7 and an NGI type, were used to compare the radial stresses developed in the NGI-type SSA with the horizontal normal stresses on the plane perpendicular to the plane of shear deformation and the intermediate principal effective stresses as measured in the Cambridge University SSA Mk7. These stresses are often assumed to be equal. Monotonic and cyclic simple shear tests were conducted on dense and loose Leighton Buzzard sand at constant applied vertical load. Comparison of results shows that the radial stresses are equal to neither the horizontal normal stresses nor the intermediate principal effective stress ratio and the horizontal stress ratio reached at peak stress ratio (maximum shear stress/vertical) in monotonic tests on sand in its initial densest state represent threshold values for cyclic simple shear tests. Auth.
861041 Bearing capacity of gravity bases on layered soil Georgiadis, M; Michalopoulos, A P d Geotech Engng Div A S C E V I I I , N6, June 1985. P712-729 A simple numerical method for evaluating the bearing capacity of shallow foundations on layered soil is presented. Several potential failure surfaces are analyzed and the minimum material factor for which the foundation is stable is determined. Comparisons between the results obtained with the new method, a number of semi-empirical solutions for uniform and two-layer systems, experiments and other numerical methods including finite elements provide a valuable assessment of the performance of the various methods currently used and demonstrate the validity of the new method. Auth.
861043 Cyclic loading and modeling of interfaces Desai, C S: Drumm. E C: Zaman, M M J Geotech Engng Dir A S C E 1"111, N6. June 19~5, P793-,~'15 A new device for cyclic testing of large size interfaces between structural and geologic materials and rock joints is described. Test results are reported for a sand-concrete interface, and arc used to express shear stress as function of normal stress, relative displacement, number of loading cycles and initial density. Constitutive behaviour of the interface is expressed as nonlinear elastic and simulates loading-unloading-reloading response by using a modified Ramberg-Osgood model. The parameters for the models are found from a series of cyclic displacement controlled tests. Predictions of the constitutive model and a finite element analysis arc compared with observed test behaviour. Auth.
861044 Creep, dilatancy and compressibility of rocks around pressure shafts and oil wells (In French) Cristescu, N Rev Fr Geotech N31, 1985. Pll-22 For oil well bores or pressure shafts, it is important to know whether the rock surrounding the bore is dilatant or compressible. An elasto-viscoplastic constitutive equation is proposed which can describe the compressibility and'or dilatancy of the rock. Stress and strain fields around the bore can be determined and creep and stress relaxation studied. The stress state, depth and pressure inside the well at which the rock around the well becomes dilatant, and thus absorbs the liquid present, can be determined. Using this model, possible methods of avoiding this rock dilatancy problem are discussed, and numerical examples are given for a hard rock and one less hard.
861045 Micromechanisms for plastic deformation of a granular soil (In French) Cambou, B Rev Fr Geotech N31, 1985, P39-51 A static analysis is proposed to examine the mechanisms of plastic deformation of a granular material and the factors controlling these mechanisms. Starting from first principles, a two-dimensional analysis is made of grains of equal size in an irregular array. The angular distribution of contact forces is used to identify and define two strain hardening mechanisms, one related to the mean contact force, the other to the range of values of contact forces. The model can explain many experimentally observed properties of granular materials.
861046 Mechanical properties and strength anisotropy of decomposed granite soil
861042 Strength of intact geomechanical materials
Onitsuka, K; Yoshitake, S; Nanri, M Soils Found 1/25, N2, June 1985, P14-30
Johnston, I W d Geotech Engng Div A S C E Vl11. N6, June 1985, P730-749
Direct shear tests have been carried out on undisturbed and compacted decomposed granite soils. Shear strength characteristics and the influence of soaking and compaction method were examined. Strength anisotropy was examined by direct shear tests on specimens with failure planes parallel to and perpendicular to the vertical. Compacted soil shows lower shear strength than undisturbed soil, and method of compaction also affects strength. Soaking weakens compacted soils more than undisturbed samples, which is explained in terms of apparent cohesion. A schematic soil structure is proposed to explain the behaviour.
The strength of geomechanical materials can be described by a number of strength criteria. However, each criterion is usually limited to certain material types with a limited range of stress conditions. A new empirical strength criterion is proposed and shown to apply to a wide range of intact materials, from lightly overconsolidated clays through hard rocks, for both compressive and tensile stress regions. It is demonstrated that the strengths of these widely differing materials follow a distinctive progressive pattern. Auth. 81 refs.