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Field observation and analysis of wave-induced liquefaction in seabed
297A
Sadcl, M H; Lun Qiu; Boardman, W G; Shukla, A Int J Rock Mech Min Sci V29, N2, March 1992, P161-170
925190 P-wave velocity in granulites from South India: implications for the continental crust Ramachandran, C Tectonophysics V201, NI/2, Jan 1992, P187-198
An analysis for wave propagation in granular media has been developed in which dynamic load transfer between adjacent particles is simulated by a special finite element. The particulate medium is modelled by an elastic network which accounts for contact interaction and local microstructure. Displacement and rotation of particles are taken into account and normal and tangential forces can be calculated. Results from model tests on photoelastic materials were used in calibration of the analysis. Reasonable results are seen with linear stiffness and damping, but improvements are expected if nonlinearity is introduced.
P wave velocities were measured for 160 high grade metamorphic rocks from granulite terrain. The wide range in Vp for the charnockites and gneisses may be due to their complex prograde and retrograde metamorphic histories. Velocity-density relations show distinct trends for both rock types. Laboratory mean Vp of these rocks is consistent with mid-crustal DSS velocity in adjacent granite greenstone terrain, suggesting this rock may be underlain by a felsic granulite basement. Physical properties of the granulites are, however, inferior to those of lower crustal rocks, indicating they may not be of lower crustal origin.
925186 MndeHing wave propagation in granular media using elastic networks. Technical note
925187 Pore alignment between two dissimilar saturated poroelastic media: reflection and refraction at the interface Sharma, M D; Saini, T int J Solids Struct V29, N i l , 1992, P1361-1377 Elastic wave propagation in fluid saturated porous media is of interest to many disciplines and has been widely studied. Little attention has, however, been paid to wave propagation at a poroelastic/poroelastic interface, where boundary conditions depend on the connection between the interstices of the two media in contact. Blot theory is here used to study reflection and refraction of plane harmonic waves at such an interface. Effects of pore alignment of the two media on amplification and energy ratios are evaluated.
925188 Rayleigh wave propagation in horizontal layered models of the Western Continental Margin of the Iberian Peninsula Fitas, A J S; Mendes-Victor, L A Rev Gcofis V47, N2, 1991, P179-189
925191 Role of Rayleigh-waves in rock fragmentation Rossmanith, H P; Knasmillner, R E Proc 3rd International Symposium o n Rock Fragmentation by Blasting, Brisbane, 26-31 August 1990 P109-116. Publ Parkville: Aus[MM, 1990 Body waves from blasting interact with geometric surfaces producing Rayleigh waves. These propagate along free surfaces, most of the energy being concentrated within the vicinity of the surface. A very strong mixed mode stress intensity factor may result when Rayl¢igh waves interact with a crack front, which can result in fracture initiation. Photoclastic laboratory tests have been used to study history of the dynamic stress intensity factor resulting from interaction of Rayleigh waves with normal and inclined surface cracks. 925192 Interdisciplinary characterization of the FR! fracture zone Long, J C S; Majer, E L; Myer, L R; Peterson, J E; Karasaki, K; Martel, S J Proc 7th I S R M International Congress on Rock Meclumics, Aachen, 16-20 September 1991 VI. P549-556. Publ Rotterdam: A A Balkema, 1991
A finite element study of the propagation of Rayleigh waves in two semi-infinite, horizontally layered zones, representing the oceanic and continental zones of the western continental region of the Iberian peninsula, is presented. Wave periods of 1.5-60s are considered. Channel propagation is found under certain conditions. The physical character of the medium of propagation determines the difference in behaviour in the upper and lower zones.
An easily accessible fracture zone in the Grimsel Laboratory was studied in order to determine the fundamentals of seismic wave propagation in fractured media and to relate geophysical and hydraulic properties. Geologic analysis, laboratory core studies, seismic tomographic imaging, hydrological tests, and it situ stiffness measurements were carried out. The hydraulic significance of kakirite beating fractures identified by tomography is confirmed by hydraulic tests. The geomechanical tests were important in understanding the in situ seismic behaviour. Practicality of the integrated approach is demonstrated.
925189 Field observation and analysis of wave-induced liquefaction in seabed Zen, K; Yamazaki, H Soils Found V31, N4, Dec 1991, P161-179
925193 Effects of temperature on swelling of coal shale Huang, S L; Speck, R C; Wang, Z Proc 8th Annual Workshop Generic Mineral Technology Center Mine Systems Design and Ground Control, Reno, 5-6 November 1990 P75-85. Pubi Blacksburg: Virginia Polytechnic Institute and State University, 1990
Pore pressures and effective stress variations were measured in the breaker zone of a porous seabed. The wave-induced liquefaction is examined using a liquefaction criterion considering the spatial difference of the pore pressures in the seabed. Observed and estimated oscillatory pore pressures are compared. Factors influencing effective stress in the seabed are discussed. It is shown that the liquefaction potential of the seabed can be evaluated using the proposed criterion. Waveinduced liquefaction is closely related to upward seepage flow induced as a result of rapid lowering of the sea surface during passage of a wave trough.
Coal shales are known to absorb water, swell, and degrade on exposure to the atmosphere. The interaction with water becomes more complex at temperatures below freezing. Ultrasonic wave velocity as a function of temperature (0 to -10 deg C) has been evaluated for a range of sandy silty and clay soils. A power law relation is seen. Temperature and unfrozen water content are the two most significant parameters. Initial swelling tests on a variety of shales at 23 deg C are also reported. Effects of mineralogy and microstructure, humidity, and pore fluid chemistry are briefly discussed.
© 1992 Pergamon Press Ltd. Reproduction not permitted
Sadcl, M H; Lun Qiu; Boardman, W G; Shukla, A Int J Rock Mech Min Sci V29, N2, March 1992, P161-170
925190 P-wave velocity in granulites from South India: implications for the continental crust Ramachandran, C Tectonophysics V201, NI/2, Jan 1992, P187-198
An analysis for wave propagation in granular media has been developed in which dynamic load transfer between adjacent particles is simulated by a special finite element. The particulate medium is modelled by an elastic network which accounts for contact interaction and local microstructure. Displacement and rotation of particles are taken into account and normal and tangential forces can be calculated. Results from model tests on photoelastic materials were used in calibration of the analysis. Reasonable results are seen with linear stiffness and damping, but improvements are expected if nonlinearity is introduced.
P wave velocities were measured for 160 high grade metamorphic rocks from granulite terrain. The wide range in Vp for the charnockites and gneisses may be due to their complex prograde and retrograde metamorphic histories. Velocity-density relations show distinct trends for both rock types. Laboratory mean Vp of these rocks is consistent with mid-crustal DSS velocity in adjacent granite greenstone terrain, suggesting this rock may be underlain by a felsic granulite basement. Physical properties of the granulites are, however, inferior to those of lower crustal rocks, indicating they may not be of lower crustal origin.
925186 MndeHing wave propagation in granular media using elastic networks. Technical note
925187 Pore alignment between two dissimilar saturated poroelastic media: reflection and refraction at the interface Sharma, M D; Saini, T int J Solids Struct V29, N i l , 1992, P1361-1377 Elastic wave propagation in fluid saturated porous media is of interest to many disciplines and has been widely studied. Little attention has, however, been paid to wave propagation at a poroelastic/poroelastic interface, where boundary conditions depend on the connection between the interstices of the two media in contact. Blot theory is here used to study reflection and refraction of plane harmonic waves at such an interface. Effects of pore alignment of the two media on amplification and energy ratios are evaluated.
925188 Rayleigh wave propagation in horizontal layered models of the Western Continental Margin of the Iberian Peninsula Fitas, A J S; Mendes-Victor, L A Rev Gcofis V47, N2, 1991, P179-189
925191 Role of Rayleigh-waves in rock fragmentation Rossmanith, H P; Knasmillner, R E Proc 3rd International Symposium o n Rock Fragmentation by Blasting, Brisbane, 26-31 August 1990 P109-116. Publ Parkville: Aus[MM, 1990 Body waves from blasting interact with geometric surfaces producing Rayleigh waves. These propagate along free surfaces, most of the energy being concentrated within the vicinity of the surface. A very strong mixed mode stress intensity factor may result when Rayl¢igh waves interact with a crack front, which can result in fracture initiation. Photoclastic laboratory tests have been used to study history of the dynamic stress intensity factor resulting from interaction of Rayleigh waves with normal and inclined surface cracks. 925192 Interdisciplinary characterization of the FR! fracture zone Long, J C S; Majer, E L; Myer, L R; Peterson, J E; Karasaki, K; Martel, S J Proc 7th I S R M International Congress on Rock Meclumics, Aachen, 16-20 September 1991 VI. P549-556. Publ Rotterdam: A A Balkema, 1991
A finite element study of the propagation of Rayleigh waves in two semi-infinite, horizontally layered zones, representing the oceanic and continental zones of the western continental region of the Iberian peninsula, is presented. Wave periods of 1.5-60s are considered. Channel propagation is found under certain conditions. The physical character of the medium of propagation determines the difference in behaviour in the upper and lower zones.
An easily accessible fracture zone in the Grimsel Laboratory was studied in order to determine the fundamentals of seismic wave propagation in fractured media and to relate geophysical and hydraulic properties. Geologic analysis, laboratory core studies, seismic tomographic imaging, hydrological tests, and it situ stiffness measurements were carried out. The hydraulic significance of kakirite beating fractures identified by tomography is confirmed by hydraulic tests. The geomechanical tests were important in understanding the in situ seismic behaviour. Practicality of the integrated approach is demonstrated.
925189 Field observation and analysis of wave-induced liquefaction in seabed Zen, K; Yamazaki, H Soils Found V31, N4, Dec 1991, P161-179
925193 Effects of temperature on swelling of coal shale Huang, S L; Speck, R C; Wang, Z Proc 8th Annual Workshop Generic Mineral Technology Center Mine Systems Design and Ground Control, Reno, 5-6 November 1990 P75-85. Pubi Blacksburg: Virginia Polytechnic Institute and State University, 1990
Pore pressures and effective stress variations were measured in the breaker zone of a porous seabed. The wave-induced liquefaction is examined using a liquefaction criterion considering the spatial difference of the pore pressures in the seabed. Observed and estimated oscillatory pore pressures are compared. Factors influencing effective stress in the seabed are discussed. It is shown that the liquefaction potential of the seabed can be evaluated using the proposed criterion. Waveinduced liquefaction is closely related to upward seepage flow induced as a result of rapid lowering of the sea surface during passage of a wave trough.
Coal shales are known to absorb water, swell, and degrade on exposure to the atmosphere. The interaction with water becomes more complex at temperatures below freezing. Ultrasonic wave velocity as a function of temperature (0 to -10 deg C) has been evaluated for a range of sandy silty and clay soils. A power law relation is seen. Temperature and unfrozen water content are the two most significant parameters. Initial swelling tests on a variety of shales at 23 deg C are also reported. Effects of mineralogy and microstructure, humidity, and pore fluid chemistry are briefly discussed.
© 1992 Pergamon Press Ltd. Reproduction not permitted