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Failure of granite under compression
3A
loading. It was found to increase with increasing fracture stress, the increase for the static loading case being higher than for the dFnamlc case. In both cases the velocity reaches a limiting value for stresses higher than a certain level. T81021 REVIEW OF FATIGUE-CRACK-GROWTH PREDICTION METHODS Nelson, D V ExpMech, V17, N2, Feb 1977, P41-49 An up-to-date review with 50 refs. 781022 NUM~ICAL STUDY OF T W O - D I ~ S I O N A L SPONTANEOUS RUPEE PROPAGATION Des, S; Aki, K Geophys J R Astr Soc, V50, N3, Sept 1977, P643-668 An earthquake source is modelled as a 2-dz~ionalpropagating shear crack in an infinite, isotropic, homogeneous, elastic solid.
Strength characteristics 781023 USE OF IRREGULAR SPECIMENS FOR ROCK STR~GTH TESTS Brook, N Int J Rock Mech Min Sci, Vl~, N4, July 1977, P103-202 The lump test, point load test, crushing tests and hardness tests are critically reviewed. The fundamental aspects of i~x~rtance, namely the dependence of the energy required to break rock on the new surface area created for some processes, and on the test specimen volume for other processes, are considered and shown to be experimentally verifiable but limited to specific types of tests. More consistent and convenient versions, capable of being performed with irregular specimens, are described for point load, crushing and impact strength tests.
781024 EFFECT OF FLUID INJECTION ON THE FRACTURE BEHAVIOUR OF POROUS ROCK Gowd, T N; Runnel, F Int J Rock Mech Min Sci, Vl~, Nh, July 1977, P203-208 Laboratory triaxial tests on sandstone specimens under triaxial compression were conducted to investigate the influence of pore fluid pressure on the deformation and fracture behaviour of rock. The experiments have shown that changes in the boundary stresses are produced by either expansion or contraction of the porous rock and that increase or decrease of boundary stresses will depend on whether the rock was initially deformed elastically or inelastically, respectively. The experiments determine the bulk modulus of the solid phase of the porous material as well as the coefficient of sliding friction along inclined crack surfaces. The results ~ be applied to field situations and they demonstrate that the fluid pressure alone does not cause fracture instability of a porous rock mass. Instability is dependent rather on the stiffnesses of the rock masses involved.
781025 FAILURE OF GRANITE UNDER COMPRESSION Janash, W Int J Rock Mech Min Scl, V14, Nh, July 1977, P209-215 Strength data for Westerly granite under triaxial compression up to a confining pressure of 800 MN/sq m reveal a quadratic relationship between maximum stress end confining pressure. Neither the Coulomb nor the G~iffith failure criteria are adequate for representing these data. A failure model based on the difference of elastic constants of the constituent minerals and a mechanism of structural instability yields the correct relation between maximum stress and confining pressure. The model can also explain some typical experimental observations, in particular the formation of a shear fault in the presence of confining pressure. 781026 ESTIMATE FOR BEARING CAPACITY OF A PRISMATIC PILLAR Giger, M W; Krizek, R J Rock Mech, V9, Nh, July 1977, P189-211 The upper bound theorem of the generalized theory of perfect plasticity was applied in conjunction with a simple curve fitting scheme to estimate the average vertical bearing capacity of a rectangular pillar with variable width-to-height and width-to-length ratios. In general, it was found that the pillar bearing pressure depends linearly on the pillar width-to-ler~th ratio. Design charts were developed for various ratios of the unconfined compressive strength to the uniaxial tensile strength by plotting the normalized average bearing pressure versus the pillar width-to-height ratio for the two limiting values of zero and one for the pillar widthto-length ratio. 781027 S I N G I ~ P A R A ~ MODELS FOR PROGRESSIVE WEAKlING OF SOILS BY CYCLIC LOADING van Eekelen, H A M Geotechnique, V27, N3, 1977, P357-368 The modelling of soil behaviour Under random cyclic loading is important in studies of gravity structure foundation stability under severe storms. The underlying assumptions of the procedures involved are discussed and a general single-parameter theory is formulated and applied to compare and catalogue existing models. The inter-relation of stress- and strain-controlled tests is discussed and some new methods for obtaining or testing empirical models are indicated.
781028 REANALYSIS OF SIMPLE SHEAR SOIL TESTING Prevost, J H; Hoeg, K Can Geotech J, VI3, N4, Nov 1976, P418-429 Existing isotropic elastic saalyses of stresses and strains in the simple shear test are extended, and the effects of partial differential boundary slippage at the interface between the soil specimen and the top and bottom caps of the apparatus are analyzed. A comparison is made between constant volume and truly undrained simple shear tests. An applied simple shear state of strain will not in general produce a simple sheer state
loading. It was found to increase with increasing fracture stress, the increase for the static loading case being higher than for the dFnamlc case. In both cases the velocity reaches a limiting value for stresses higher than a certain level. T81021 REVIEW OF FATIGUE-CRACK-GROWTH PREDICTION METHODS Nelson, D V ExpMech, V17, N2, Feb 1977, P41-49 An up-to-date review with 50 refs. 781022 NUM~ICAL STUDY OF T W O - D I ~ S I O N A L SPONTANEOUS RUPEE PROPAGATION Des, S; Aki, K Geophys J R Astr Soc, V50, N3, Sept 1977, P643-668 An earthquake source is modelled as a 2-dz~ionalpropagating shear crack in an infinite, isotropic, homogeneous, elastic solid.
Strength characteristics 781023 USE OF IRREGULAR SPECIMENS FOR ROCK STR~GTH TESTS Brook, N Int J Rock Mech Min Sci, Vl~, N4, July 1977, P103-202 The lump test, point load test, crushing tests and hardness tests are critically reviewed. The fundamental aspects of i~x~rtance, namely the dependence of the energy required to break rock on the new surface area created for some processes, and on the test specimen volume for other processes, are considered and shown to be experimentally verifiable but limited to specific types of tests. More consistent and convenient versions, capable of being performed with irregular specimens, are described for point load, crushing and impact strength tests.
781024 EFFECT OF FLUID INJECTION ON THE FRACTURE BEHAVIOUR OF POROUS ROCK Gowd, T N; Runnel, F Int J Rock Mech Min Sci, Vl~, Nh, July 1977, P203-208 Laboratory triaxial tests on sandstone specimens under triaxial compression were conducted to investigate the influence of pore fluid pressure on the deformation and fracture behaviour of rock. The experiments have shown that changes in the boundary stresses are produced by either expansion or contraction of the porous rock and that increase or decrease of boundary stresses will depend on whether the rock was initially deformed elastically or inelastically, respectively. The experiments determine the bulk modulus of the solid phase of the porous material as well as the coefficient of sliding friction along inclined crack surfaces. The results ~ be applied to field situations and they demonstrate that the fluid pressure alone does not cause fracture instability of a porous rock mass. Instability is dependent rather on the stiffnesses of the rock masses involved.
781025 FAILURE OF GRANITE UNDER COMPRESSION Janash, W Int J Rock Mech Min Scl, V14, Nh, July 1977, P209-215 Strength data for Westerly granite under triaxial compression up to a confining pressure of 800 MN/sq m reveal a quadratic relationship between maximum stress end confining pressure. Neither the Coulomb nor the G~iffith failure criteria are adequate for representing these data. A failure model based on the difference of elastic constants of the constituent minerals and a mechanism of structural instability yields the correct relation between maximum stress and confining pressure. The model can also explain some typical experimental observations, in particular the formation of a shear fault in the presence of confining pressure. 781026 ESTIMATE FOR BEARING CAPACITY OF A PRISMATIC PILLAR Giger, M W; Krizek, R J Rock Mech, V9, Nh, July 1977, P189-211 The upper bound theorem of the generalized theory of perfect plasticity was applied in conjunction with a simple curve fitting scheme to estimate the average vertical bearing capacity of a rectangular pillar with variable width-to-height and width-to-length ratios. In general, it was found that the pillar bearing pressure depends linearly on the pillar width-to-ler~th ratio. Design charts were developed for various ratios of the unconfined compressive strength to the uniaxial tensile strength by plotting the normalized average bearing pressure versus the pillar width-to-height ratio for the two limiting values of zero and one for the pillar widthto-length ratio. 781027 S I N G I ~ P A R A ~ MODELS FOR PROGRESSIVE WEAKlING OF SOILS BY CYCLIC LOADING van Eekelen, H A M Geotechnique, V27, N3, 1977, P357-368 The modelling of soil behaviour Under random cyclic loading is important in studies of gravity structure foundation stability under severe storms. The underlying assumptions of the procedures involved are discussed and a general single-parameter theory is formulated and applied to compare and catalogue existing models. The inter-relation of stress- and strain-controlled tests is discussed and some new methods for obtaining or testing empirical models are indicated.
781028 REANALYSIS OF SIMPLE SHEAR SOIL TESTING Prevost, J H; Hoeg, K Can Geotech J, VI3, N4, Nov 1976, P418-429 Existing isotropic elastic saalyses of stresses and strains in the simple shear test are extended, and the effects of partial differential boundary slippage at the interface between the soil specimen and the top and bottom caps of the apparatus are analyzed. A comparison is made between constant volume and truly undrained simple shear tests. An applied simple shear state of strain will not in general produce a simple sheer state