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Response of poroelastic layers to moving loads
8A
D y n a m i c properties 851061 Near-field source characterization of contained nuclear explosions in tuff Stump, B W; Johnson, L R Bull Seismol Soe Am V74, N1, Feb 1984, P1-26 The seismic sources of three contained nuclear explosions in tuff are characterised, by applying the moment tensor source representation to near-field accelerometer recordings of the events.
851062 Exact solution of the problem of an SH pulse in a layered elastic half-space Abramovici, F Bull Seismol Soc Am V74, N2, April 1984, P377-393 851063 Apparatus for investigating earthquake-induced liquefaction experimentally. Technical note Morris, D V Can Geoteeh J V20, N4, No~' 1983, P840-845 An apparatus that simulates earthquake-induced liquefaction using a centrifuge has been developed. Instrumentation allows dynamic motion and cyclieaUy generated pore pressures to be measured. Modelling laws allow measurements to be related directly to an equivalent full-scale prototype. A pilot test has been carried out.
851064 Microstructural changes associated with thixotropic phenomena in clay soils Osipov, V I; Nikolaeva, S K; Sokolov, V N Geoteehnique V34, N3, Sept 1984, P293-303 A laboratory investigation was carried out in order to clarify the mechanism of thixotropic phenomena by examining the microstructural changes occurring in soils during deformation in a rotary viscometer with and without vibration. In the tests without vibration clay deformation occurs over a limited volume, the shear zone, accompanied by marked changes in the microstructure. In the tests with vibration the microstructure becomes more homogeneous and the shear zone disappears. In kaolinite clay and coarser dispersed soils (silty clay, watersaturated loess) the local areas of the structural framework (shear planes) become smoother and the orientation of the structural elements along the direction of the shear disappears. After vibration is halted the microstructure is rapidly restored to its initial state.
851065 Response of poroelastic layers to moving loads Burke, M; Kingsbury, H B lnt J Solids Struct 1120, NS, 1984, P499-511 Blot theory together with Fourier Transform techniques are used to study the response of a fluid-filled porous elastic material to surface tractions moving at constant speed. Layer response to a moving porous indenter and to a moving fluid pressure wave is determined. The fluid flow, pressure and stress distributions for the two cases are found to be markedly different.
851066 Shear and compression wave measurements in shocked polycrystalline aluminium oxide Gupta, Y M J Geophys Res V88, NB5, 10 May 1983, P4304-4312
An experimental technique has been developed that permits measurement of the velocity and amplitude of shear waves as well as compression waves in shocked geologic solids. Experimental measurements up to 90kbar compressive shock stresses were obtained for aluminium oxide. The shear wave velocity data is in good agreement with extrapolated ultrasonic test results.
851067 Frequency dependent ultrasonic properties of high-porosity sandstones Winkler, K W J Geophys Res V88, NB11, 10 Noc 1983. P9493-9499 Compressional wave phase velocities and attenuation have been measured in several high-porosity (20-26°0) sandstones, as a continuous function of frequency from 400kHz to 2MHz. Both dry and brine saturated samples were studied at effective pressures up to 40MPa. Dry samples all showed negative velocity dispersion and attenuation increasing as the third to fourth power of frequency. These data are interpreted as evidence of scattering within the samples. Brine saturated rocks showed positive velocity dispersion and attenuation increasing with a first to second power frequency dependence. These data are interpreted as evidence for a local fluid-flow loss mechanism.
851068 Bulk thermoelastic attenuation of composite materials Budiansky, B; Sumner, E E; O'ConneU, R J J Geophys Res V88, NB12, 10 Dec 1983. P10343-10348 A theoretical derivation for the effective, frequency-dependent thermoelastic bulk modulus of an isotropic composite, subjected to hydrostatic stress, producing volumetric strain is presented. Parametric studies show the influence of various elastic and thermal properties on thermoelastic damping. Numerical calculations are made for a hypothetical lower mantle assemblage of stishovite and magnesiowustite. The results show that thermoelastic dissipation in the lower mantle can account for the observed attenuation of the fundamental radial normal mode and can provide constraints on grain size.
851069 Nature of seismic reflections from deep crustal fault zones Jones, T D; Nur, A J Geophys Res V89, NB5, 10 May 1984. P3153-3171 Deep seismic reflection profiles that have recorded reflections from ductile shear zones within the crystalline basement are presented. From measurements of compressional wave velocity and velocity anisotropy in mylonites, recovered from exhumed ductile shear zones, the physical properties responsible for the seismic reflections from fault zones are identified. Seismic modelling of the amplitude and frequency content of reflections from thrust faults indicates that they are caused by a laminar structure of alternating high- and low-velocity zones. It is also shown that elevated pore pressure in shear zones may produce strong reflections. 61 refs.
851070 Boundary layer theory for Rayleigh Waves in a porous, fluidfilled half space Foda, M A; Mei, C C Soil Dynam Earthq Eagng V2, N2, April 1983, P62-65 A general boundary layer approximation of Blot's equations is used to study the propagation of Rayleigh waves through a fluid-filled half space. The results from the leading order solution are used in second order calculations to obtain the damping effect.
D y n a m i c properties 851061 Near-field source characterization of contained nuclear explosions in tuff Stump, B W; Johnson, L R Bull Seismol Soe Am V74, N1, Feb 1984, P1-26 The seismic sources of three contained nuclear explosions in tuff are characterised, by applying the moment tensor source representation to near-field accelerometer recordings of the events.
851062 Exact solution of the problem of an SH pulse in a layered elastic half-space Abramovici, F Bull Seismol Soc Am V74, N2, April 1984, P377-393 851063 Apparatus for investigating earthquake-induced liquefaction experimentally. Technical note Morris, D V Can Geoteeh J V20, N4, No~' 1983, P840-845 An apparatus that simulates earthquake-induced liquefaction using a centrifuge has been developed. Instrumentation allows dynamic motion and cyclieaUy generated pore pressures to be measured. Modelling laws allow measurements to be related directly to an equivalent full-scale prototype. A pilot test has been carried out.
851064 Microstructural changes associated with thixotropic phenomena in clay soils Osipov, V I; Nikolaeva, S K; Sokolov, V N Geoteehnique V34, N3, Sept 1984, P293-303 A laboratory investigation was carried out in order to clarify the mechanism of thixotropic phenomena by examining the microstructural changes occurring in soils during deformation in a rotary viscometer with and without vibration. In the tests without vibration clay deformation occurs over a limited volume, the shear zone, accompanied by marked changes in the microstructure. In the tests with vibration the microstructure becomes more homogeneous and the shear zone disappears. In kaolinite clay and coarser dispersed soils (silty clay, watersaturated loess) the local areas of the structural framework (shear planes) become smoother and the orientation of the structural elements along the direction of the shear disappears. After vibration is halted the microstructure is rapidly restored to its initial state.
851065 Response of poroelastic layers to moving loads Burke, M; Kingsbury, H B lnt J Solids Struct 1120, NS, 1984, P499-511 Blot theory together with Fourier Transform techniques are used to study the response of a fluid-filled porous elastic material to surface tractions moving at constant speed. Layer response to a moving porous indenter and to a moving fluid pressure wave is determined. The fluid flow, pressure and stress distributions for the two cases are found to be markedly different.
851066 Shear and compression wave measurements in shocked polycrystalline aluminium oxide Gupta, Y M J Geophys Res V88, NB5, 10 May 1983, P4304-4312
An experimental technique has been developed that permits measurement of the velocity and amplitude of shear waves as well as compression waves in shocked geologic solids. Experimental measurements up to 90kbar compressive shock stresses were obtained for aluminium oxide. The shear wave velocity data is in good agreement with extrapolated ultrasonic test results.
851067 Frequency dependent ultrasonic properties of high-porosity sandstones Winkler, K W J Geophys Res V88, NB11, 10 Noc 1983. P9493-9499 Compressional wave phase velocities and attenuation have been measured in several high-porosity (20-26°0) sandstones, as a continuous function of frequency from 400kHz to 2MHz. Both dry and brine saturated samples were studied at effective pressures up to 40MPa. Dry samples all showed negative velocity dispersion and attenuation increasing as the third to fourth power of frequency. These data are interpreted as evidence of scattering within the samples. Brine saturated rocks showed positive velocity dispersion and attenuation increasing with a first to second power frequency dependence. These data are interpreted as evidence for a local fluid-flow loss mechanism.
851068 Bulk thermoelastic attenuation of composite materials Budiansky, B; Sumner, E E; O'ConneU, R J J Geophys Res V88, NB12, 10 Dec 1983. P10343-10348 A theoretical derivation for the effective, frequency-dependent thermoelastic bulk modulus of an isotropic composite, subjected to hydrostatic stress, producing volumetric strain is presented. Parametric studies show the influence of various elastic and thermal properties on thermoelastic damping. Numerical calculations are made for a hypothetical lower mantle assemblage of stishovite and magnesiowustite. The results show that thermoelastic dissipation in the lower mantle can account for the observed attenuation of the fundamental radial normal mode and can provide constraints on grain size.
851069 Nature of seismic reflections from deep crustal fault zones Jones, T D; Nur, A J Geophys Res V89, NB5, 10 May 1984. P3153-3171 Deep seismic reflection profiles that have recorded reflections from ductile shear zones within the crystalline basement are presented. From measurements of compressional wave velocity and velocity anisotropy in mylonites, recovered from exhumed ductile shear zones, the physical properties responsible for the seismic reflections from fault zones are identified. Seismic modelling of the amplitude and frequency content of reflections from thrust faults indicates that they are caused by a laminar structure of alternating high- and low-velocity zones. It is also shown that elevated pore pressure in shear zones may produce strong reflections. 61 refs.
851070 Boundary layer theory for Rayleigh Waves in a porous, fluidfilled half space Foda, M A; Mei, C C Soil Dynam Earthq Eagng V2, N2, April 1983, P62-65 A general boundary layer approximation of Blot's equations is used to study the propagation of Rayleigh waves through a fluid-filled half space. The results from the leading order solution are used in second order calculations to obtain the damping effect.