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Regularities in the shear behaviour of Pleistocene and Pannon soil complexes along the Danube River
PROPERTIES:DEFORMATION & STRENGTH mined as a function of the prism strength. An empirical relationship is given. (P.M.Taylor)
962130 Micromechanieal modelling of tensile response of elasticbrittle materials Xi-Qiao Feng & Shou-Wen Yu, International Journal of Solids & Structures, 32(22), 1995, pp 3359-3372. The stress-strain relation of elastic-brittle materials under tensile loading includes some of the stages of linear elasticity, pre-peak non-imear hardening, rapid stress drop and tension softening. This paper gives the complete constitutive relation including the four stages of an elastic-brittle material subjected to uniaxial and triaxial tensile loads. As an illustration, the theoretical stress-strain curve in uniaxial tension is compared with an experimental result. (from Authors) 962131 An elnsto-plastie constitutive model for soft rock with strain softening T. Adachi & F. Oka, International Journal for Numerical & Analytical Methods in Geomechanics, 19(4), 1995, pp 233247. The aim of this paper is to construct a constitutive model of soft rock that can describe not only the strain-hardening hehaviour, but also the strain-softening behaviour. An elastoplastic constitutive model for soft rock is derived by introducing a stress history tensor. The model is evaluated through a comparison of the calculated results and the experimental results of tests on sedimentary soft rock (porous tuff). In addition, the applicability of the model to numerical analyses is discussed in relation to the uniqueness of the solution in initial and boundary value problems. (Authors) 962132 Estimates of elastic moduli for granular material with anisotropic random packing structure Ching S. Chang, Sao J. Chao & Y. Chang, International Journal of Solids & Structures, 32(14), 1995, pp 1989-2008. For randomly packed spheres, the packing structure can be characterized by a fabric tensor representing the orientation distribution of inter-particle contacts. Utilizing the fabric tensor, elastic moduli of granular material with anisotropic packing structures are derived in explicit terms of interparticle properties. The derivation is based on two different methods, namely the kinematic method and the static method. Results derived from kinematic and static methods provide, respectively, the upper and lower estimates of elastic moduli. Ranges of elastic moduli are discussed for granular materials with different inter-particle properties and fabric parameters. (Authors) 962133 Tensile stress concentration and compressive failure in cemented granular material Teng-fong Wong & Li-Chun Wu, Geophysical Research Letters, 22(13), 1995, pp 1649-1652. The finite element technique was used to simulate the tensile stress concentration and normal stiffness in a cemented aggregate. The detrital grains were assumed to be elastically identical spheres bonded by cement layers of finite thickness. The numerical simulations show that the maximum tensile stress concentration is located near the triple junction (among grain, cement and pore space), and its magnitude is signifieantly less that that for an uncemented system. The development of micro-cracking near a cemented contact is readily inhibited unless the applied stress exceeds a critical value which is at least an order of magnitude greater than that for the onset of Hertzian fracture. (from Authors) 962134 Damage mechanisms in stressed rock from acoustic emission K. R. Shah & J. F. Labuz, Journal of Geophysical Research, 100(B8), 1995, pp 15,527-15,539.
65A
To better understand the phenomena leading to the failure of rock, unconfined compression experiments on Charcoal granite specimens were performed with the monitoring of acoustic emission (AE). Localization in the form of spalling near the free surface was detected by the concentration of hypocenters. The A E locations,which look random in space and time before localization,actuallywere clustered and have fractal structure in either space or time. The dominant mode of failurefrom A E was siding on inclined planes, although a significant number of source planes were parallel to the loading axis,while the growth of cracks perpendicular to the loading axis was inhibited. This preferential growth of microcracks is related to a tensorial measure of damage and is used to study stress-inducedanisotropy. (from Authors)
962135 Deformation-strength-density H. Hejj, Periodica Polytechnica: Civil Engineering, 38(1), 1994, pp 49-55. Over 60 triaxial tests were carried out on samples of the same lateritic soil at previously set moisture contents, densities and side pressures. The test results allowed conclusions to he drawn about the influence of these variables on the continuous alteration of strength and deformation, correlated by internal strength parameters cr and c. (from Author) 962136 Up-to-date means of shear strength tests: comparison between simple and direct shear I. Szabo, Periodica Polytechnica: Civil Engineering, 38(1), 1994, pp 109-126. A modern laboratory for shear-strength testing has been developed in the last 10 years at the Department of Hydrogeology and Engineering Geology at University of Miskolc. The computer-controlled triaxial equipment is able to perform tests at different stress paths. The computer controlled ring shear equipment is suitable for constant volume testing. The wall friction can also be measured. The study compares the shear equipment based on direct or simple shear theory, analyses the stress distribution, deformation fields inside the sample, and formation of failure planes. (from Autho0 962137 Regularities in the shear behaviour of Pleistocene and Pannon soil complexes along the Danube River I. Kabai, Periodica Polytechnica: Civil Engineering, 38(1), 1994, pp 57-66. The aim of this study was to produce and analyse the regularities of shearing properties of soils, identified by routine testing methods for the sequential soil masses of the Pleistocene and Pannon escarpment walls along the western bank of the Danube. The study was able to prove that significantly more information can be achieved about the shearing properties of individual soil samples and sequential soil masses on the basis of known and introduced failure criteria. (from Author) 962138 Geotechnical behaviour of safine sabkha soils S. N. Abduljauwad & O. S. B. AI-Amoudi, Geotechnique, 45(3), 1995, pp 425-445. The behaviour of salt-cemented sabkha soil was investigated by considering the effect of brine and distilled water on its properties. Laboratory and field testing programmes were conducted. Results indicate that the percolation of distilled water through the sabkha causes destruction of the natural cementation, leading to collapse, increase in permeability, reduction in strength and increase in settlement. Dissolution and leaching of halite, gypsiferous and calcarenite cements occur, leaving the quartz particles covered by a thin loose mat of illitic clay with large voids. The collapse deformation of sabkha is linked to the ambient salt complex. The soaking of sabkha produces practically negligible collapse; leaching causes a significant collapse due to the softening, dissolution and effusion of salts from the soil skeleton. (from Authors)
962130 Micromechanieal modelling of tensile response of elasticbrittle materials Xi-Qiao Feng & Shou-Wen Yu, International Journal of Solids & Structures, 32(22), 1995, pp 3359-3372. The stress-strain relation of elastic-brittle materials under tensile loading includes some of the stages of linear elasticity, pre-peak non-imear hardening, rapid stress drop and tension softening. This paper gives the complete constitutive relation including the four stages of an elastic-brittle material subjected to uniaxial and triaxial tensile loads. As an illustration, the theoretical stress-strain curve in uniaxial tension is compared with an experimental result. (from Authors) 962131 An elnsto-plastie constitutive model for soft rock with strain softening T. Adachi & F. Oka, International Journal for Numerical & Analytical Methods in Geomechanics, 19(4), 1995, pp 233247. The aim of this paper is to construct a constitutive model of soft rock that can describe not only the strain-hardening hehaviour, but also the strain-softening behaviour. An elastoplastic constitutive model for soft rock is derived by introducing a stress history tensor. The model is evaluated through a comparison of the calculated results and the experimental results of tests on sedimentary soft rock (porous tuff). In addition, the applicability of the model to numerical analyses is discussed in relation to the uniqueness of the solution in initial and boundary value problems. (Authors) 962132 Estimates of elastic moduli for granular material with anisotropic random packing structure Ching S. Chang, Sao J. Chao & Y. Chang, International Journal of Solids & Structures, 32(14), 1995, pp 1989-2008. For randomly packed spheres, the packing structure can be characterized by a fabric tensor representing the orientation distribution of inter-particle contacts. Utilizing the fabric tensor, elastic moduli of granular material with anisotropic packing structures are derived in explicit terms of interparticle properties. The derivation is based on two different methods, namely the kinematic method and the static method. Results derived from kinematic and static methods provide, respectively, the upper and lower estimates of elastic moduli. Ranges of elastic moduli are discussed for granular materials with different inter-particle properties and fabric parameters. (Authors) 962133 Tensile stress concentration and compressive failure in cemented granular material Teng-fong Wong & Li-Chun Wu, Geophysical Research Letters, 22(13), 1995, pp 1649-1652. The finite element technique was used to simulate the tensile stress concentration and normal stiffness in a cemented aggregate. The detrital grains were assumed to be elastically identical spheres bonded by cement layers of finite thickness. The numerical simulations show that the maximum tensile stress concentration is located near the triple junction (among grain, cement and pore space), and its magnitude is signifieantly less that that for an uncemented system. The development of micro-cracking near a cemented contact is readily inhibited unless the applied stress exceeds a critical value which is at least an order of magnitude greater than that for the onset of Hertzian fracture. (from Authors) 962134 Damage mechanisms in stressed rock from acoustic emission K. R. Shah & J. F. Labuz, Journal of Geophysical Research, 100(B8), 1995, pp 15,527-15,539.
65A
To better understand the phenomena leading to the failure of rock, unconfined compression experiments on Charcoal granite specimens were performed with the monitoring of acoustic emission (AE). Localization in the form of spalling near the free surface was detected by the concentration of hypocenters. The A E locations,which look random in space and time before localization,actuallywere clustered and have fractal structure in either space or time. The dominant mode of failurefrom A E was siding on inclined planes, although a significant number of source planes were parallel to the loading axis,while the growth of cracks perpendicular to the loading axis was inhibited. This preferential growth of microcracks is related to a tensorial measure of damage and is used to study stress-inducedanisotropy. (from Authors)
962135 Deformation-strength-density H. Hejj, Periodica Polytechnica: Civil Engineering, 38(1), 1994, pp 49-55. Over 60 triaxial tests were carried out on samples of the same lateritic soil at previously set moisture contents, densities and side pressures. The test results allowed conclusions to he drawn about the influence of these variables on the continuous alteration of strength and deformation, correlated by internal strength parameters cr and c. (from Author) 962136 Up-to-date means of shear strength tests: comparison between simple and direct shear I. Szabo, Periodica Polytechnica: Civil Engineering, 38(1), 1994, pp 109-126. A modern laboratory for shear-strength testing has been developed in the last 10 years at the Department of Hydrogeology and Engineering Geology at University of Miskolc. The computer-controlled triaxial equipment is able to perform tests at different stress paths. The computer controlled ring shear equipment is suitable for constant volume testing. The wall friction can also be measured. The study compares the shear equipment based on direct or simple shear theory, analyses the stress distribution, deformation fields inside the sample, and formation of failure planes. (from Autho0 962137 Regularities in the shear behaviour of Pleistocene and Pannon soil complexes along the Danube River I. Kabai, Periodica Polytechnica: Civil Engineering, 38(1), 1994, pp 57-66. The aim of this study was to produce and analyse the regularities of shearing properties of soils, identified by routine testing methods for the sequential soil masses of the Pleistocene and Pannon escarpment walls along the western bank of the Danube. The study was able to prove that significantly more information can be achieved about the shearing properties of individual soil samples and sequential soil masses on the basis of known and introduced failure criteria. (from Author) 962138 Geotechnical behaviour of safine sabkha soils S. N. Abduljauwad & O. S. B. AI-Amoudi, Geotechnique, 45(3), 1995, pp 425-445. The behaviour of salt-cemented sabkha soil was investigated by considering the effect of brine and distilled water on its properties. Laboratory and field testing programmes were conducted. Results indicate that the percolation of distilled water through the sabkha causes destruction of the natural cementation, leading to collapse, increase in permeability, reduction in strength and increase in settlement. Dissolution and leaching of halite, gypsiferous and calcarenite cements occur, leaving the quartz particles covered by a thin loose mat of illitic clay with large voids. The collapse deformation of sabkha is linked to the ambient salt complex. The soaking of sabkha produces practically negligible collapse; leaching causes a significant collapse due to the softening, dissolution and effusion of salts from the soil skeleton. (from Authors)