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Experimental investigation of the stress-strain state of a layer of weak soil underlain by a low-compressibility mass
26A
transparent pistons, optical holography, microscopy, and sound velocity measurements were used as tools to study the processes leading to brittle failure. At about 50 per cent of ultimate failure stremgt~ a zone of preferential deformation forms around the incipient fault, and the sei~nic velocities decrease perpendicular to the axis of maximum principal stress. At higher stress levels the intense dsformation zone becomes v ~ V marrow and the velocities increase again before failure. En echelon cracks form and precede the formation of a macrocrack and a stress drop. It is believed that the presence of water as a volatile, not as a pressure fluid, affected the results. Relates to earthquake prediction models.
792049
EXPERIMENTAL INVESTIGATION OF THE STRESS-STRAIN STATE OF A LAYER OF WEAK SOIL UNDerLAIN BY A LOW-COMPRESSIBILITY MASS Vyalov, S S; Mirdich, A L Soil Mech Found Engngs VI4, NI, Jan-Feb 1977,
formability. This in-situ test program was accompanied by detailed laboratory tests on all rock types er~ountered at the site, to establish a correlation between the laboratory and the in-situ test data. Uncertainties posed by in situ tests are demongtrated, and a new approach based on the Geomechanlcs Classification of rock masses is proposed. 30 refs. 792053 EFFECT OF FREEZE-THAW CYCLES ON RESILIENt PROPERTIES OF FINE-GRAINED SOILS Johnson, T C; Cole, D M; Chamberlain, E J US Army Cold Regions Research and Engineering Lab report MP 1082, 1978, 19P 792054 MECHANICAL BEHAVIOUR OF FROZEN SOILS UNDER TRIAXIAL COMPRESSION Neuber, H; Wolters, R Canada: National Research Council technical translation 1902, 1977, 53P
P48-54 Describes triaxial compression tests on clay soil and discusses the mathematics of the stressstrain relationships obtained. Results show that it is advantageous to use a non linear deforming model when designing foundation beds in weak soils. 792050 DESIGN OF A SANDY FOUNDATION BED BY MEANS OF PHYSICALLY AND M A T H ~ T I C A L L Y NONLINEAR EQUATIONS Kopelkin, V S; Solomln, V I Soil Mech Found E r ~ s VIM, N1, Jan-Feb 1977,
Time dependent behaviour See also: 792045 792055 APPROACH TO CREEP BEHAVIOUR IN FAILED ROCKS Cogan, J Proc 19th US Symposium on Rock Mechanics, Stateline, Nevada, 1-3 May 1978, Vl, P400407. Publ Reno: University of Nevada, 1978 A review of recent research in rock creep is presented. Two rarges of creep behaviour are defined: pre-failure creep and post-failure creep. In the post-failure range, creep deformations will occur under decreasing applied stresses. The "unloading line" of the surrounding rock and the "failure line" of the creeping rock will place bounds upon how creep deformations will occur as the stress drops. Changes in regional stresses as brought about by mining, will serve to reposition the reference point for creep, and will lead to either sudden creep rate increases or decreases. Two extreme cases are defined which place limits upon how creep will progress in a mine pillar.
P55-58 Considers the physical ar~ geometric nonlinearity of deformation of soil in the foundation bed, when calculating strains and stresses for design purposes. 792051 CRITICAL STATE YIELD CRITERION FOR STRAINSOFTENING ROCK Brown, E T; Michelis, P N Proc 19th US symposium on Rock Mechanics, Stateline, NeVada, 1-3 May 1978, Vl, P515519. Publ Reno: University of Nevada, 1978 A yield criterion for isotropic, homogeneous, straln-sc~tenfng rocks and rock masses has been developed by medlfyimg the equations of critical state soil mechanics to account for the work absorbed in brittle fracture mechanisms. The theory invokes the ass~nptions of the incremental theory of plasticity including that of norreality. A close match with peak atrength data for a wide range of strain-softening rocks can be obtained from the critical state criterion, providing some evidence of the validity and usefulness of the approach. Auth. 792052 CRITICAL ASSESSMENT OF IN SITU TESTS FOR DEFORMABILITY AND STRESS MEASUREMENTS Bieniawski, Z T Proc 19th US Symposium on Rock Mechanics, Stateline, N~,cada, 1-3 May 1978, Vl, P523529. Publ Reno: University of Nevada, 1978 Reports a recently completed research program which permitted systematic evaluation of ten selected in-situ teat methods based on over lO0 in-situ tests. The investigation included 2 methods of stress measurement and 8 different techniques for determining rock mass de-
792056
FATIGUE TESTS OF OIL SHALE Chang, B; Costello, K; Chong, K P Proc 19th US Symposi~n on Rock Mechanics, Stateline, NeVada, 1-3 May 1978 , V1, P408413. Publ Reno: University of NeVada, 1978 Deals with the influence of cyclic loading on oil shale from Wyemlng. Effects of organic content on endurance limits are discussed. The endurance limit is defined as the maximum stress the material can be subjected to without failure by fatigue. In addition combined effects of organic content amd stress levels on the n ~ e r of cycles before failure are presented.
RELAXATION OF OIL SHALE 792057 CREEP ~ Chomg, K P; Smith, J W; Khaliki, B A Proc 19th US Symposium on Rock Mechanics, stateline, Nevada, 1-3 May 1978, V1, P414418. Publ Reno: University of Nevada, 1978 The set of duplicate test specimens required for creep testing were cut from a single oil shale layer using a wire saw to avoid any surface damage. A rheological model was developed
transparent pistons, optical holography, microscopy, and sound velocity measurements were used as tools to study the processes leading to brittle failure. At about 50 per cent of ultimate failure stremgt~ a zone of preferential deformation forms around the incipient fault, and the sei~nic velocities decrease perpendicular to the axis of maximum principal stress. At higher stress levels the intense dsformation zone becomes v ~ V marrow and the velocities increase again before failure. En echelon cracks form and precede the formation of a macrocrack and a stress drop. It is believed that the presence of water as a volatile, not as a pressure fluid, affected the results. Relates to earthquake prediction models.
792049
EXPERIMENTAL INVESTIGATION OF THE STRESS-STRAIN STATE OF A LAYER OF WEAK SOIL UNDerLAIN BY A LOW-COMPRESSIBILITY MASS Vyalov, S S; Mirdich, A L Soil Mech Found Engngs VI4, NI, Jan-Feb 1977,
formability. This in-situ test program was accompanied by detailed laboratory tests on all rock types er~ountered at the site, to establish a correlation between the laboratory and the in-situ test data. Uncertainties posed by in situ tests are demongtrated, and a new approach based on the Geomechanlcs Classification of rock masses is proposed. 30 refs. 792053 EFFECT OF FREEZE-THAW CYCLES ON RESILIENt PROPERTIES OF FINE-GRAINED SOILS Johnson, T C; Cole, D M; Chamberlain, E J US Army Cold Regions Research and Engineering Lab report MP 1082, 1978, 19P 792054 MECHANICAL BEHAVIOUR OF FROZEN SOILS UNDER TRIAXIAL COMPRESSION Neuber, H; Wolters, R Canada: National Research Council technical translation 1902, 1977, 53P
P48-54 Describes triaxial compression tests on clay soil and discusses the mathematics of the stressstrain relationships obtained. Results show that it is advantageous to use a non linear deforming model when designing foundation beds in weak soils. 792050 DESIGN OF A SANDY FOUNDATION BED BY MEANS OF PHYSICALLY AND M A T H ~ T I C A L L Y NONLINEAR EQUATIONS Kopelkin, V S; Solomln, V I Soil Mech Found E r ~ s VIM, N1, Jan-Feb 1977,
Time dependent behaviour See also: 792045 792055 APPROACH TO CREEP BEHAVIOUR IN FAILED ROCKS Cogan, J Proc 19th US Symposium on Rock Mechanics, Stateline, Nevada, 1-3 May 1978, Vl, P400407. Publ Reno: University of Nevada, 1978 A review of recent research in rock creep is presented. Two rarges of creep behaviour are defined: pre-failure creep and post-failure creep. In the post-failure range, creep deformations will occur under decreasing applied stresses. The "unloading line" of the surrounding rock and the "failure line" of the creeping rock will place bounds upon how creep deformations will occur as the stress drops. Changes in regional stresses as brought about by mining, will serve to reposition the reference point for creep, and will lead to either sudden creep rate increases or decreases. Two extreme cases are defined which place limits upon how creep will progress in a mine pillar.
P55-58 Considers the physical ar~ geometric nonlinearity of deformation of soil in the foundation bed, when calculating strains and stresses for design purposes. 792051 CRITICAL STATE YIELD CRITERION FOR STRAINSOFTENING ROCK Brown, E T; Michelis, P N Proc 19th US symposium on Rock Mechanics, Stateline, NeVada, 1-3 May 1978, Vl, P515519. Publ Reno: University of Nevada, 1978 A yield criterion for isotropic, homogeneous, straln-sc~tenfng rocks and rock masses has been developed by medlfyimg the equations of critical state soil mechanics to account for the work absorbed in brittle fracture mechanisms. The theory invokes the ass~nptions of the incremental theory of plasticity including that of norreality. A close match with peak atrength data for a wide range of strain-softening rocks can be obtained from the critical state criterion, providing some evidence of the validity and usefulness of the approach. Auth. 792052 CRITICAL ASSESSMENT OF IN SITU TESTS FOR DEFORMABILITY AND STRESS MEASUREMENTS Bieniawski, Z T Proc 19th US Symposium on Rock Mechanics, Stateline, N~,cada, 1-3 May 1978, Vl, P523529. Publ Reno: University of Nevada, 1978 Reports a recently completed research program which permitted systematic evaluation of ten selected in-situ teat methods based on over lO0 in-situ tests. The investigation included 2 methods of stress measurement and 8 different techniques for determining rock mass de-
792056
FATIGUE TESTS OF OIL SHALE Chang, B; Costello, K; Chong, K P Proc 19th US Symposi~n on Rock Mechanics, Stateline, NeVada, 1-3 May 1978 , V1, P408413. Publ Reno: University of NeVada, 1978 Deals with the influence of cyclic loading on oil shale from Wyemlng. Effects of organic content on endurance limits are discussed. The endurance limit is defined as the maximum stress the material can be subjected to without failure by fatigue. In addition combined effects of organic content amd stress levels on the n ~ e r of cycles before failure are presented.
RELAXATION OF OIL SHALE 792057 CREEP ~ Chomg, K P; Smith, J W; Khaliki, B A Proc 19th US Symposium on Rock Mechanics, stateline, Nevada, 1-3 May 1978, V1, P414418. Publ Reno: University of Nevada, 1978 The set of duplicate test specimens required for creep testing were cut from a single oil shale layer using a wire saw to avoid any surface damage. A rheological model was developed