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Strength and deformation characteristics of jointed media in true triaxial compression
24A
792030 HYDRAULIC FRACTURING IN POROUS ROCK WITH PARTICULAR R E ~ E TO VERTICAL FRACTURE BOUNDARIES Kim, C M; Gray, K E Proc l ~ h US Sympesi~n on Rock Mechanics, Stateline, Nevada, i-3 May 1978, VI, P327332. Publ Reno: University of Nevada, 1978 Reports the early stages of an experimental investigation to observe fracture shape while it is being created amd extended. Fracturing sequence was detected by monitoring the arrival times of the fracture edge at different locatior~ inside rock samples, through embedded electrical wires. Fracture initiation, orlentation/~growth rate and width are discussed. 792031 LAB~ATORY EXPERIMENTS ON HYDRAULIC FRACTURE GROWTH NEAR AN INTERFACE Anderson, G D; Larson, D B Proc 19th US Sympositma on Rock Mechanics, Stateline, Nevada, 1-3 May 1978, Vl, P333339. Publ Reno: University of Nevada, 1978 Describes a laboratory programme in which hydraulically driven cracks are initiated in polymethylmethacrylate, limestone, and sandstone. So far, work has concentrated on the effects of applied stress loads a~d the presence of interfaces on crack growth, considering particularly interfaces from one material to another. 792032 PREDICTION OF MASSIVE HYDRAULIC FRACTURING FROM ANALYSES OF ORIENTED CORES Logan, J M; Teufel, L W Proc 19th US Symposium on Rock Mechanics, Stateline, Nevada, 1-3 May 1978, V1, PBhO34h. Publ Reno: University of Nevada, 1978 A preferred orientation of fractures induced in point load tests was founl for 5 cores from the Wattenburg gas field, Colorado, the observation being corroborated by Brazil tests and triaxial compression tests. Thin-section analyses were made of core material to ascertain the fabric elements of the rock, residual strain measurements were carried out, ard the geological setting examined. The results are compared with data from electrical potential measurements made after hydraulic fracturing. 792033 THERMAL CRACKS IN UNCONFINED SIOUX QUARTZITE Friedman, M; Johnson, B Proc 19th US Symposium on Rock Mechanicsj Stateline, Nevada, 1-3 May 1978, VI, I~23430. Publ Reno: University of Nevada, 1978 The morphology, orientation,, and abunlance of thermal cracks ere characterized in unconfined specimens of Sioux Quartzite subjected to (1) slow thermal cycling (up to 2 deg C/min) to 385 deg, 560 deg, and 685 deg C, and (2) slow heating at the same rate followed by quenching from 400 deg C. In both, all the thermal cracks are microscopic in size and occur primarily along grain boundaries and secondarily as intragranular microfractures. The abundances of parted boundaries and intragranular cracks increase with increasing maximum temperature. The erientation and symnetry of the cracks formed in both sets of specimens are considered in relationship to the thermal stresses induced.
Strength characteristics 792034 S T R E N ~ AND DEFORM~ION CHARACTERISTICS OF JOINTED MEDIA IN TRUE TRIAXIAL COMPRESSION Reik, G; Zacas, M Int J Rock Mech Min Sci, V15, N6, Dec 1978, P295-303 Lab tests were conducted on an idealized model of a Jointed rock in a specially des~ned loading arramgement umder various Joint comflgurations ani lateral stress ratios, in order to examime the influence of these factors on the mechanical behaviour of Jointed rocks. A spectr~n of different failure patterns was observed amd it became clear that the deforms~ionsl characteristics of the Jointed model samples depended on the Joint configuration amd the anlsotropy of the applied stress field. 792035 DOUBLE HARDENING MODEL FOR SAND Vermeer, P A Geotechnlque, V28, N~, 1978, P413-~33 An elastoplastic model is established for the initial loading, unloading amd reloading af samd. The plastic strains are described as the sum of two indeperzlent parts - a volumetric component due to isotropic compression, and a more important component described by means of a shear yield surface anl a non-associated flow rule incorporating Rowe's stress-dilstancy equation. Predictions of the th~c~y are in good agreement with experimental results. 792036 BOREHOLE SHEAR TEST FOR STIFF SOIL. TECHNICAL NOTE Luteregger, A J; Remmes, B D; Harmly, R L J Geotech Emgr~ Div, ASCE, VI04, NGTII, Nov 1978, P1403-1407 The Iowa Bcrehole Shear Test is a rapid, direct sheer test performed on the walls of a borehole in soil. The test measures in-situ soll shear strer4~th by failing the soil alorg the circumferemme of the hole. Sharply ridged, diametrically opposed shear plates are expanded by gas pressure to apply a normal stress against sides of the hole. A shearing stress is then applied by pulling the plates axially along the hole while maintaining a constant normal stress until failure occurs. By repeating the test with different values of norm~] stress, a series of shearing stress values are obtaimed from which a Mohr-Coulcmb failure envelope is drawn. Allowing time for drainage between successive points permits Inter~rets~ion of results on a consolidated-drained basis. Auth. 792O37 DEFORMATION AND S ~ E ~ CHARACTERISTICS OF SOFT BANGKOK CLAY Balasubramanian, A S; Cha~lhr~, A R J Geotech Er~r~ Div ASCE, VI04, N(Ffg, Sept 1978, PI153-i167 A com~rehenslve series of stress controlled trlaxial compression tests was carried out on SOft Bar~kok Cl~y. Altogether, four different types of triaxial tests were carried out and t h e s e include: (i) U r J l r a i r ~ tests with constant cell pressure and with l-hr and l-d~v load
792030 HYDRAULIC FRACTURING IN POROUS ROCK WITH PARTICULAR R E ~ E TO VERTICAL FRACTURE BOUNDARIES Kim, C M; Gray, K E Proc l ~ h US Sympesi~n on Rock Mechanics, Stateline, Nevada, i-3 May 1978, VI, P327332. Publ Reno: University of Nevada, 1978 Reports the early stages of an experimental investigation to observe fracture shape while it is being created amd extended. Fracturing sequence was detected by monitoring the arrival times of the fracture edge at different locatior~ inside rock samples, through embedded electrical wires. Fracture initiation, orlentation/~growth rate and width are discussed. 792031 LAB~ATORY EXPERIMENTS ON HYDRAULIC FRACTURE GROWTH NEAR AN INTERFACE Anderson, G D; Larson, D B Proc 19th US Sympositma on Rock Mechanics, Stateline, Nevada, 1-3 May 1978, Vl, P333339. Publ Reno: University of Nevada, 1978 Describes a laboratory programme in which hydraulically driven cracks are initiated in polymethylmethacrylate, limestone, and sandstone. So far, work has concentrated on the effects of applied stress loads a~d the presence of interfaces on crack growth, considering particularly interfaces from one material to another. 792032 PREDICTION OF MASSIVE HYDRAULIC FRACTURING FROM ANALYSES OF ORIENTED CORES Logan, J M; Teufel, L W Proc 19th US Symposium on Rock Mechanics, Stateline, Nevada, 1-3 May 1978, V1, PBhO34h. Publ Reno: University of Nevada, 1978 A preferred orientation of fractures induced in point load tests was founl for 5 cores from the Wattenburg gas field, Colorado, the observation being corroborated by Brazil tests and triaxial compression tests. Thin-section analyses were made of core material to ascertain the fabric elements of the rock, residual strain measurements were carried out, ard the geological setting examined. The results are compared with data from electrical potential measurements made after hydraulic fracturing. 792033 THERMAL CRACKS IN UNCONFINED SIOUX QUARTZITE Friedman, M; Johnson, B Proc 19th US Symposium on Rock Mechanicsj Stateline, Nevada, 1-3 May 1978, VI, I~23430. Publ Reno: University of Nevada, 1978 The morphology, orientation,, and abunlance of thermal cracks ere characterized in unconfined specimens of Sioux Quartzite subjected to (1) slow thermal cycling (up to 2 deg C/min) to 385 deg, 560 deg, and 685 deg C, and (2) slow heating at the same rate followed by quenching from 400 deg C. In both, all the thermal cracks are microscopic in size and occur primarily along grain boundaries and secondarily as intragranular microfractures. The abundances of parted boundaries and intragranular cracks increase with increasing maximum temperature. The erientation and symnetry of the cracks formed in both sets of specimens are considered in relationship to the thermal stresses induced.
Strength characteristics 792034 S T R E N ~ AND DEFORM~ION CHARACTERISTICS OF JOINTED MEDIA IN TRUE TRIAXIAL COMPRESSION Reik, G; Zacas, M Int J Rock Mech Min Sci, V15, N6, Dec 1978, P295-303 Lab tests were conducted on an idealized model of a Jointed rock in a specially des~ned loading arramgement umder various Joint comflgurations ani lateral stress ratios, in order to examime the influence of these factors on the mechanical behaviour of Jointed rocks. A spectr~n of different failure patterns was observed amd it became clear that the deforms~ionsl characteristics of the Jointed model samples depended on the Joint configuration amd the anlsotropy of the applied stress field. 792035 DOUBLE HARDENING MODEL FOR SAND Vermeer, P A Geotechnlque, V28, N~, 1978, P413-~33 An elastoplastic model is established for the initial loading, unloading amd reloading af samd. The plastic strains are described as the sum of two indeperzlent parts - a volumetric component due to isotropic compression, and a more important component described by means of a shear yield surface anl a non-associated flow rule incorporating Rowe's stress-dilstancy equation. Predictions of the th~c~y are in good agreement with experimental results. 792036 BOREHOLE SHEAR TEST FOR STIFF SOIL. TECHNICAL NOTE Luteregger, A J; Remmes, B D; Harmly, R L J Geotech Emgr~ Div, ASCE, VI04, NGTII, Nov 1978, P1403-1407 The Iowa Bcrehole Shear Test is a rapid, direct sheer test performed on the walls of a borehole in soil. The test measures in-situ soll shear strer4~th by failing the soil alorg the circumferemme of the hole. Sharply ridged, diametrically opposed shear plates are expanded by gas pressure to apply a normal stress against sides of the hole. A shearing stress is then applied by pulling the plates axially along the hole while maintaining a constant normal stress until failure occurs. By repeating the test with different values of norm~] stress, a series of shearing stress values are obtaimed from which a Mohr-Coulcmb failure envelope is drawn. Allowing time for drainage between successive points permits Inter~rets~ion of results on a consolidated-drained basis. Auth. 792O37 DEFORMATION AND S ~ E ~ CHARACTERISTICS OF SOFT BANGKOK CLAY Balasubramanian, A S; Cha~lhr~, A R J Geotech Er~r~ Div ASCE, VI04, N(Ffg, Sept 1978, PI153-i167 A com~rehenslve series of stress controlled trlaxial compression tests was carried out on SOft Bar~kok Cl~y. Altogether, four different types of triaxial tests were carried out and t h e s e include: (i) U r J l r a i r ~ tests with constant cell pressure and with l-hr and l-d~v load