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Influence of nearby fractures on stress measurements by hydraulic fracturing
215A 805099 Effect of cementation on the cone penetration resistance of sand Rad, N S; Tumay, M T In: Use of In Situ Tests in Geoteclmical Engineering (papers to the Conference, Blacksburg, 23-25 Jane 1986) P926-948. Pubi New York: ASCE, 1986 (ASCE Geotechnical Special Publication No 6) Using uncemented and artificially cemented laboratory prepared sand samples and a miniature quasi-static cone penetrometer, the influence of relative density and cementation of the sample on cone penetration resistance was studied. The effect of these variables on drained strength parameters was evaluated using triaxial tests. Results indicate cementation has a significant effect on the mechanical properties of sand.
885100 Reinforcing effect of rockbolt in rock joint model Yoshinaka, R; Shimizu, T; Sakaguchi, S; Arai, H; Kato, E Proc International Symposium on Engineering in Complex Rock Formations, Bering, 3-7 November 1986 P922-928. Publ Beijing: Science Press, 1986
Large scale shear tests were carried out on mortar models simulating jointed rocks and reinforced with rock bolts. The apparatus, loading method, and results of the tests are shown. Finite element numerical analysis was used to model the rock joints and the bolts.
885101 Evaluation of bearing capacity of foundation ground for weathered granite Ishiwata, K, Yamada, K Proc International Symposium on Engineering in Complex Rock Formations, Beijing, 3-7 November 1986 P973-982. Publ Beijing: Science Press, 1986
Granite rock suffers very significant strength loss on weathering. The influence of overburden pressure cannot be neglected, and deformational and bearing capacity properties vary with depth. Weathered granite rock masses are thus best evaluated as multilayer systems. Using analysis of results of in situ tests, and laboratory tests at different confining pressures, a method was developed to estimate the bearing capacity and time dependent behaviour of weathered granite.
Fracture
processes
See also: 885040, 885466
885102 Use of permeability as an index to characterise internal structural changes and fracture mechanism: technical note Lee, D H; Juang, C H Geotecll Test J VII. NI. March 1988. P63-67
Avail: A simple testing method to characterise the fracture mechanism of a soft rock specimen during triaxial compression by measuring rock permeability is presented. Since internal structure directly affects permeability, the total change of internal structure is inferred from variation of permeability during testing. Triaxial compression tests, triaxial tests with relaxations and cyclic triaxial tests were conducted and illustrate the validity of the method.
885103 Influence of nearby fractures on stress measurements by hydraulic fracturing Wu, M; Wang, H F lnt J Rock Meek Min Sci 1/25, NI, Feb 1988, P15-23
The interaction between a vertical borehole and a nearby vertical fracture is modelled by an infinite plane containing a circular hole and a crack. Analytical expressions for the stress field are obtained in terms of integral equations. The solution may be used to indicate the effects of varying length and location of the crack on stress distribution at the borehole. Numerical results indicate the effect of the crack is weak when the crack length is short or the distance between the crack and the hole is relatively large. The model is applied to hydraulic fracturing data from Illinois, and suggests that the presence of nearby fractures is the likely cause of deviation between orientation of hydraulic fractures and the direction of maximum remote stress.
885104 Engineering of hydraulic fractures - state of the art and technology of the future Cleary, M P J Pet Tech V40, NI, Jan 1988, P13-21
Increased computing power and better materials models have allowed real time evaluation and control of the hydrofracturing process in the field. The basic components of design procedures are described. Hydrofracturing models and methods of establishing their credibility and usefulness are considered, and field applications discussed. Results from various models are illustrated and compared with field measurements. Possible advances for the future are considered.
885105 Hydraulic-fracture-treatment design simulation Acharya, R J Pet Tech V40, N2, Feb 1988, P139-142
Computer simulations of hydraulic fracturing treatments incorporate combinations of rock properties, fluid properties, and process variables. 2D, pseudo-3D, and 3D simulations are available, and many complex phenomena are considered in the fracture process. Assumptions and requirements differ from model to model, but a fully 3D model requires input of fracture mechanics and rock/fluid interaction information to be accurately run and interpreted.
885106 Fracture toughness testing of rock cores Hsiao, C; El Rabaa, A W Proc 28th US Symposium on Rock Mechanics, Tucson, 29 Jane-! July 1987 P141-148. Publ Rotterdam: A A Balkema, 1987
Three point bending core-based chevron-notched specimens were prepared in 4 rock types and load tested. The stress intensity coefficient was determined semi-analytically and the plasticity correction factor graphically, to calculate the fracture toughness of the rock. The values derived are approximately 20 to 35% below corrected ones in which plasticity corrections are applied.
© 1988 Pergamon Press plc. Reproduction not permitted
885100 Reinforcing effect of rockbolt in rock joint model Yoshinaka, R; Shimizu, T; Sakaguchi, S; Arai, H; Kato, E Proc International Symposium on Engineering in Complex Rock Formations, Bering, 3-7 November 1986 P922-928. Publ Beijing: Science Press, 1986
Large scale shear tests were carried out on mortar models simulating jointed rocks and reinforced with rock bolts. The apparatus, loading method, and results of the tests are shown. Finite element numerical analysis was used to model the rock joints and the bolts.
885101 Evaluation of bearing capacity of foundation ground for weathered granite Ishiwata, K, Yamada, K Proc International Symposium on Engineering in Complex Rock Formations, Beijing, 3-7 November 1986 P973-982. Publ Beijing: Science Press, 1986
Granite rock suffers very significant strength loss on weathering. The influence of overburden pressure cannot be neglected, and deformational and bearing capacity properties vary with depth. Weathered granite rock masses are thus best evaluated as multilayer systems. Using analysis of results of in situ tests, and laboratory tests at different confining pressures, a method was developed to estimate the bearing capacity and time dependent behaviour of weathered granite.
Fracture
processes
See also: 885040, 885466
885102 Use of permeability as an index to characterise internal structural changes and fracture mechanism: technical note Lee, D H; Juang, C H Geotecll Test J VII. NI. March 1988. P63-67
Avail: A simple testing method to characterise the fracture mechanism of a soft rock specimen during triaxial compression by measuring rock permeability is presented. Since internal structure directly affects permeability, the total change of internal structure is inferred from variation of permeability during testing. Triaxial compression tests, triaxial tests with relaxations and cyclic triaxial tests were conducted and illustrate the validity of the method.
885103 Influence of nearby fractures on stress measurements by hydraulic fracturing Wu, M; Wang, H F lnt J Rock Meek Min Sci 1/25, NI, Feb 1988, P15-23
The interaction between a vertical borehole and a nearby vertical fracture is modelled by an infinite plane containing a circular hole and a crack. Analytical expressions for the stress field are obtained in terms of integral equations. The solution may be used to indicate the effects of varying length and location of the crack on stress distribution at the borehole. Numerical results indicate the effect of the crack is weak when the crack length is short or the distance between the crack and the hole is relatively large. The model is applied to hydraulic fracturing data from Illinois, and suggests that the presence of nearby fractures is the likely cause of deviation between orientation of hydraulic fractures and the direction of maximum remote stress.
885104 Engineering of hydraulic fractures - state of the art and technology of the future Cleary, M P J Pet Tech V40, NI, Jan 1988, P13-21
Increased computing power and better materials models have allowed real time evaluation and control of the hydrofracturing process in the field. The basic components of design procedures are described. Hydrofracturing models and methods of establishing their credibility and usefulness are considered, and field applications discussed. Results from various models are illustrated and compared with field measurements. Possible advances for the future are considered.
885105 Hydraulic-fracture-treatment design simulation Acharya, R J Pet Tech V40, N2, Feb 1988, P139-142
Computer simulations of hydraulic fracturing treatments incorporate combinations of rock properties, fluid properties, and process variables. 2D, pseudo-3D, and 3D simulations are available, and many complex phenomena are considered in the fracture process. Assumptions and requirements differ from model to model, but a fully 3D model requires input of fracture mechanics and rock/fluid interaction information to be accurately run and interpreted.
885106 Fracture toughness testing of rock cores Hsiao, C; El Rabaa, A W Proc 28th US Symposium on Rock Mechanics, Tucson, 29 Jane-! July 1987 P141-148. Publ Rotterdam: A A Balkema, 1987
Three point bending core-based chevron-notched specimens were prepared in 4 rock types and load tested. The stress intensity coefficient was determined semi-analytically and the plasticity correction factor graphically, to calculate the fracture toughness of the rock. The values derived are approximately 20 to 35% below corrected ones in which plasticity corrections are applied.
© 1988 Pergamon Press plc. Reproduction not permitted