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Seismic wave propagation across multiple fractures
162A properties of soapstone masonry, and effects of presence of pore fluids where crack to pore hydraulic connections are important are illustrated in detail. 93318O Seismic wave propagation across multiple fractures Myer, L R; Hopkins, D; Peterson, J E; Cook, N G W
Proc Conference on Fractured and Jointed Rock Masses, Lake Tahoe, 3-5 June 1992 Pl13-117. Publ California: Lawrence Berkeley Laboratory, 1992 Where detailed resolution of rock structures is required from geophysical data, the effects of each discrete fracture on wave propagation must be evaluated. Results of a theoretical approach to model effects of single fractures using a displacement discontinuity theory are discussed. Laboratory measurements which support the theory and demonstrate its applicability to multifracture systems are summarised. The ability of theory to replicate field measurements made in a fractured basalt rock mass is finally illustrated. 933181 Interrelationship between the hydraulic and seismic properties of fractures Pyrak-Nolte, L J Proc Conference on Fractured and Jointed Rock Masses, Lake Tahoe, 3-5 Jane 1992 Pl18-125. Publ California: Lawrence Berkeley Laboratory, 1992 Relations between fracture specific stiffness, fluid flow through the fracture, and apparent wave attenuation have been investigated. A stratified continuum percolation model is used to generate fracture void topologies to model flow through the fracture, its mechanical displacement, and fracture specific stiffness. Effects of the fracture on P and S wave transmission are examined using a displacement discontinuity model. Specific stiffness is seen to be the primary link between hydraulic and seismic characteristics of discrete fractures. Experimental data plots of fluid flow against fracture stiffness or against transmitted wave energy for three different fractures fall on a common curve. 933182 Characterization of diseontinnom rock masses in the field with sLlrface waves Nadianos, M N; Nelson, P P; Stokoe, K H Proc Conference on Fractured and Jointed Rock Masses, Lake Tahoe, 3-5 June 1992 P191-198. Publ California: Lawrence Berkeley Laboratory, 1992 The Spectral Analysis of Surface Waves (SASW) method is widely applied to field nondestructive evaluation of stiffness variations in rock masses. The advantages of exponential windowing of time records when interpreting SASW data are illustrated. Tests are described from a quarry in Austin White Lime, with discontinuous and blast-damaged rock, and from the WIPP. In the latter, elastic properties have been seen to change in the period 1988-1990, probably as a result of stress relief. It is also shown that some near-surface examinations may only sample intact rock. 933183 Liqeefactioa poteatinl in ~ u r c h McCnhon, I F; Elder, D M; Yetton, M D Prnc 6th Aastralia-New Zealaml Coteference on GeomeckaMcs, Clwistckureh, 3-7 Fehntury 1992 P526-531. Publ New Zealand: New Zealand Geomechanics Society, 1992 Liquefaction potential of Christchurch has recently been reviewed. At least one third of the urban area is built on a generally sandy soil profile with high water table. For soils for
which adequate test data exist, analysis suggests that liquefaction is likely during an earthquake with return period about 30 years (based on regional seismicity levels). Liquefaction has not been reported in Christchurch, but it appears that an earthquake of sufficient magnitude to cause liquefaction has not occurred since European settlement. The potential for liquefaction in Christchurch is significant, but scarcity of quality data prevents hazard zonation. 933184 Undrained shear behaviour of sand under surface wave stress conditions Sugano, T; Yanagisawa, E Proc Ninth Asian Regional Conference on Soil Mechanics and Foundation Engineering, Bangkok, 9-13 December 1991 V1,
P71-74. Publ Thailand." Southeast Asian Geotechnical Society, 1991 Undrained deformation characteristics of sands under stress state conditions simulating those during Love wave or Raleigh wave propagation have been studied. A biaxial shear apparatus is used to simulate the former. A hollow cylinder torsional shear apparatus is used for the case of principal stress axis rotation, as in the Raleigh wave propagation condition. Liquefaction resistance is seen to be influenced by the inherent and induced anisotropy of the specimen and by direction and shape of stress path. 933185 Cyclic strength and deformation characteristics of saturated sand in plane strain tests Uchida, Y; Kimata, T; Hasegawa, T
Proc Ninth Asian Regional Conference on Soil Mechanics and Foundation Engineering, Bangkok, 9-13 December 1991 V1, P91-94. Publ Thailand." Southeast Asian Geotechnical Society, 1991 Liquefaction resistance of saturated Toyoura sand has been examined in cyclic plane strain tests. The undrained strength obtained was similar to that in cyclic torsional shear and greater than that in cyclic triaxial shear. Anisotropically consolidated samples failed as a result of accumulation of plastic strain with decrease in effective confining pressure. The intermediate principal stress was dependent on major and minor principal stresses in a large strain domain of the plane strain conditions. These deformation characteristics should be considered when formulating constitutive models for sand structures subject to dynamic loads. 933156 Prediction of preventing liquefaction of improved soil by threed i m e m / o ~ an~ym Fukutake, K; Ohtsuki, A
Proc lnternatiomd Comference on Geotedudcal F~tgincering
for Coastal De~lopment, GEO-COAST~I, Yokakama, 3-6 September 1991 P447-452. Publ Japan: Coastal Development Institute of Technology, 1991 It is difficult using 2D analysis to evaluate the earthquake resistance of a soil containing 3D inhomogeneities and under multi-directional loading. A 3D effective stress analysis is proposed for assessment of liquefaction resistance of sandy ground containing wall type (partial)or lattice-likeimprovement. The constitutive model is based on the RambbrgOsgood model combined with the 'Bowl' dilatancy model of Fukutake and Matsuoka 0989). Its application indicates the relativeineffectivenessof the partialimprovement and the significantincrease in excess pore water pressure when unidirectional vibration is replaced by multidirectionalexcitation.
© 1993 Pergamon Press Ltd. Reproduction not permitted
Proc Conference on Fractured and Jointed Rock Masses, Lake Tahoe, 3-5 June 1992 Pl13-117. Publ California: Lawrence Berkeley Laboratory, 1992 Where detailed resolution of rock structures is required from geophysical data, the effects of each discrete fracture on wave propagation must be evaluated. Results of a theoretical approach to model effects of single fractures using a displacement discontinuity theory are discussed. Laboratory measurements which support the theory and demonstrate its applicability to multifracture systems are summarised. The ability of theory to replicate field measurements made in a fractured basalt rock mass is finally illustrated. 933181 Interrelationship between the hydraulic and seismic properties of fractures Pyrak-Nolte, L J Proc Conference on Fractured and Jointed Rock Masses, Lake Tahoe, 3-5 Jane 1992 Pl18-125. Publ California: Lawrence Berkeley Laboratory, 1992 Relations between fracture specific stiffness, fluid flow through the fracture, and apparent wave attenuation have been investigated. A stratified continuum percolation model is used to generate fracture void topologies to model flow through the fracture, its mechanical displacement, and fracture specific stiffness. Effects of the fracture on P and S wave transmission are examined using a displacement discontinuity model. Specific stiffness is seen to be the primary link between hydraulic and seismic characteristics of discrete fractures. Experimental data plots of fluid flow against fracture stiffness or against transmitted wave energy for three different fractures fall on a common curve. 933182 Characterization of diseontinnom rock masses in the field with sLlrface waves Nadianos, M N; Nelson, P P; Stokoe, K H Proc Conference on Fractured and Jointed Rock Masses, Lake Tahoe, 3-5 June 1992 P191-198. Publ California: Lawrence Berkeley Laboratory, 1992 The Spectral Analysis of Surface Waves (SASW) method is widely applied to field nondestructive evaluation of stiffness variations in rock masses. The advantages of exponential windowing of time records when interpreting SASW data are illustrated. Tests are described from a quarry in Austin White Lime, with discontinuous and blast-damaged rock, and from the WIPP. In the latter, elastic properties have been seen to change in the period 1988-1990, probably as a result of stress relief. It is also shown that some near-surface examinations may only sample intact rock. 933183 Liqeefactioa poteatinl in ~ u r c h McCnhon, I F; Elder, D M; Yetton, M D Prnc 6th Aastralia-New Zealaml Coteference on GeomeckaMcs, Clwistckureh, 3-7 Fehntury 1992 P526-531. Publ New Zealand: New Zealand Geomechanics Society, 1992 Liquefaction potential of Christchurch has recently been reviewed. At least one third of the urban area is built on a generally sandy soil profile with high water table. For soils for
which adequate test data exist, analysis suggests that liquefaction is likely during an earthquake with return period about 30 years (based on regional seismicity levels). Liquefaction has not been reported in Christchurch, but it appears that an earthquake of sufficient magnitude to cause liquefaction has not occurred since European settlement. The potential for liquefaction in Christchurch is significant, but scarcity of quality data prevents hazard zonation. 933184 Undrained shear behaviour of sand under surface wave stress conditions Sugano, T; Yanagisawa, E Proc Ninth Asian Regional Conference on Soil Mechanics and Foundation Engineering, Bangkok, 9-13 December 1991 V1,
P71-74. Publ Thailand." Southeast Asian Geotechnical Society, 1991 Undrained deformation characteristics of sands under stress state conditions simulating those during Love wave or Raleigh wave propagation have been studied. A biaxial shear apparatus is used to simulate the former. A hollow cylinder torsional shear apparatus is used for the case of principal stress axis rotation, as in the Raleigh wave propagation condition. Liquefaction resistance is seen to be influenced by the inherent and induced anisotropy of the specimen and by direction and shape of stress path. 933185 Cyclic strength and deformation characteristics of saturated sand in plane strain tests Uchida, Y; Kimata, T; Hasegawa, T
Proc Ninth Asian Regional Conference on Soil Mechanics and Foundation Engineering, Bangkok, 9-13 December 1991 V1, P91-94. Publ Thailand." Southeast Asian Geotechnical Society, 1991 Liquefaction resistance of saturated Toyoura sand has been examined in cyclic plane strain tests. The undrained strength obtained was similar to that in cyclic torsional shear and greater than that in cyclic triaxial shear. Anisotropically consolidated samples failed as a result of accumulation of plastic strain with decrease in effective confining pressure. The intermediate principal stress was dependent on major and minor principal stresses in a large strain domain of the plane strain conditions. These deformation characteristics should be considered when formulating constitutive models for sand structures subject to dynamic loads. 933156 Prediction of preventing liquefaction of improved soil by threed i m e m / o ~ an~ym Fukutake, K; Ohtsuki, A
Proc lnternatiomd Comference on Geotedudcal F~tgincering
for Coastal De~lopment, GEO-COAST~I, Yokakama, 3-6 September 1991 P447-452. Publ Japan: Coastal Development Institute of Technology, 1991 It is difficult using 2D analysis to evaluate the earthquake resistance of a soil containing 3D inhomogeneities and under multi-directional loading. A 3D effective stress analysis is proposed for assessment of liquefaction resistance of sandy ground containing wall type (partial)or lattice-likeimprovement. The constitutive model is based on the RambbrgOsgood model combined with the 'Bowl' dilatancy model of Fukutake and Matsuoka 0989). Its application indicates the relativeineffectivenessof the partialimprovement and the significantincrease in excess pore water pressure when unidirectional vibration is replaced by multidirectionalexcitation.
© 1993 Pergamon Press Ltd. Reproduction not permitted