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Relationship between textures and sliding motion of experimentally deformed fault gouge: application to fault zone behaviour
2A
Environmental effects, weathering and soil formation 891007 Methods for estimating the critical shear stress of individual fractions in mixed-size sediment Wilcock, P R Water Resour Res V24, N7, July 1988, Pl127-1135 There are 2 methods for determining critical shear stress for individual fractions in mixed size sediment. One associates the stress with the largest grain moveable by a given flow, whilst the other approximates critical shear stress as that producing a small reference transport rate of a given fraction. A case study shows the two methods give different results, but these differences are largely methodological. A general definition of initial motion in mixed size sediment, which allows differences between the results to be explained, is presented.
Earthquake mechanisms and effects 891008 Wave scattering by a canyon of arbitrary shape in a layered half space Vogt, R F; Wolf, J P; Bachmann, H Earthq Engng Struct Dynam VI6, ?(6, Aug 1988, P803-812 The indirect boundary element method has been applied to determine the generalised scattered motion in the region of a valley of arbitrary shape in a layered half space. The importance of the combined influence of layering and topography is demonstrated. Out-of-plane and in-plane motions for inclined body waves and surface waves were examined. Amplification patterns within and adjacent to the valley are determined, and conclusions regarding region of influence, and specific layering and topographic effects presented. 891009 Influence of highly stratified dissipative soil on ground motion Xu, P C; Mal, A K Earthq Engng Struct Dynam VI6, N6, Aug 1988. P901-915 Earthquake ground motion at a given site is influenced by the mechanical properties of the soil in the vicinity. The influence of depth and properties of a sedimentary deposit consisting of a number of layers of homogeneous dissipative viscoelastic material is evaluated using a recently developed technique. Near surface low velocity layers have strong amplification effects at some frequencies. The commonly used one dimensional approach is seen to be valid at small epicentral distances only. Deamplification by material dissipation is shown to be important in most cases.
891011 Physical model for earthquakes. I. Fluctuations and interactions Rundle, J B J Geophys Res 1/93. NB6, June 1988, P6237-6254 Earthquakes are described as representing short term fluctuations about the long term motion of tectonic plates. Physical quantities which pertain to the occurrence of earthquakes depend on a physically meaningful quantity called the offset phase, the difference between the present state of slip on a fault and its long term average. Segments of a fault interact with each other during slip. A spatial averaging operation is applied to the fault plane to simplify mathematical treatment. A simplified, one dimensional earthquake model is illustrated. 891012 Modeling surface deformations at complex strike-slip plate boundaries Li, V C; Lim, H S J Geophys Res V93, NB7, July 1988, P7943-7954 An extension of the physical base traction model (Li and Rice, 1987) is presented which takes into account mechanical coupling between elastic and viscoplastic deformation and allows study of the spatial variation with distance from the fault, and time dependence over a complete earthquake cycle, of surface deformation rates. The loading and surface deformation near plate boundaries with geometric complexities, including a shallow creeping fault segment and two subparailel faults, is examined. The model produces data consistent with observations on the San Andreas fault and the Palmdale area. 891013 Relationship between textures and sliding motion of experimentally deformed fault gouge: application to fault zone behaviour Moore, D E; Summers, R; Byerlee, J D Key Questions in Rock Mechanics: Proc 29th US Symposhun, Minneapolis, 13-15 June 1988 PI03-110. Publ Rotterdam." A A Balkema, 1988 Clay rich and quartzofeldspathic fault zone materials were studied in the laboratory to investigate differences between samples that slide stably and those which show stick slip motion. Transition between sliding modes was correlated with Iocalisation of shear and increase in angle between boundary and Reidel shears. A possible earthquake mechanism proposed, based on these differences, involves localisation Of slip creating the potential for large stress build ups under favourable circumstances. This hypothesis is to be tested experimentally.
Frost action, permafrost and frozen ground See also." 891093, 891378
891010 Strain melting, the wetting transition and seismic instabilities Lomnitz-Adler, J Geophys J 1/94, NI. July 1988. P125-130 A fault mechanism is developed which involves wetting of a pre-existing planar defect by a molten phase of microscopic dimensions, lowering frictional forces on almost planar regions. For fault regions of finite thickness, this results in an order of magnitude increase in creep rate, which initiates macroscopic melting in the fault region. This mechanism can explain low stress drops and small heat flow anomalies near superficial faults, cutoff in seismicity with depth, and nonlinear deformation near the fault trace.
891014 Subsoil investigation of ice lensing at the Calgary, Canada, frost heave test facility Carlson, L E; Nixon, J F Can Geotech J 1/25, N2, May 1988, P307-319 Several frost heave mitigation modes were studied in a chilled pipeline frost heave test facility. These included deeper burial to increase pressure on the frost front below the pipe and replacement of the silty soil around the pipe with gravel for a noninsulated pipe. Frost heave at the deep burial and gravel sections was less than at the control section. Other pipe sections tested the effects of insulation of the pipe on long term frost heave and effects of replacing silt around an insulated
1989 Pergamon Press plc. Reproduction not permitted
Environmental effects, weathering and soil formation 891007 Methods for estimating the critical shear stress of individual fractions in mixed-size sediment Wilcock, P R Water Resour Res V24, N7, July 1988, Pl127-1135 There are 2 methods for determining critical shear stress for individual fractions in mixed size sediment. One associates the stress with the largest grain moveable by a given flow, whilst the other approximates critical shear stress as that producing a small reference transport rate of a given fraction. A case study shows the two methods give different results, but these differences are largely methodological. A general definition of initial motion in mixed size sediment, which allows differences between the results to be explained, is presented.
Earthquake mechanisms and effects 891008 Wave scattering by a canyon of arbitrary shape in a layered half space Vogt, R F; Wolf, J P; Bachmann, H Earthq Engng Struct Dynam VI6, ?(6, Aug 1988, P803-812 The indirect boundary element method has been applied to determine the generalised scattered motion in the region of a valley of arbitrary shape in a layered half space. The importance of the combined influence of layering and topography is demonstrated. Out-of-plane and in-plane motions for inclined body waves and surface waves were examined. Amplification patterns within and adjacent to the valley are determined, and conclusions regarding region of influence, and specific layering and topographic effects presented. 891009 Influence of highly stratified dissipative soil on ground motion Xu, P C; Mal, A K Earthq Engng Struct Dynam VI6, N6, Aug 1988. P901-915 Earthquake ground motion at a given site is influenced by the mechanical properties of the soil in the vicinity. The influence of depth and properties of a sedimentary deposit consisting of a number of layers of homogeneous dissipative viscoelastic material is evaluated using a recently developed technique. Near surface low velocity layers have strong amplification effects at some frequencies. The commonly used one dimensional approach is seen to be valid at small epicentral distances only. Deamplification by material dissipation is shown to be important in most cases.
891011 Physical model for earthquakes. I. Fluctuations and interactions Rundle, J B J Geophys Res 1/93. NB6, June 1988, P6237-6254 Earthquakes are described as representing short term fluctuations about the long term motion of tectonic plates. Physical quantities which pertain to the occurrence of earthquakes depend on a physically meaningful quantity called the offset phase, the difference between the present state of slip on a fault and its long term average. Segments of a fault interact with each other during slip. A spatial averaging operation is applied to the fault plane to simplify mathematical treatment. A simplified, one dimensional earthquake model is illustrated. 891012 Modeling surface deformations at complex strike-slip plate boundaries Li, V C; Lim, H S J Geophys Res V93, NB7, July 1988, P7943-7954 An extension of the physical base traction model (Li and Rice, 1987) is presented which takes into account mechanical coupling between elastic and viscoplastic deformation and allows study of the spatial variation with distance from the fault, and time dependence over a complete earthquake cycle, of surface deformation rates. The loading and surface deformation near plate boundaries with geometric complexities, including a shallow creeping fault segment and two subparailel faults, is examined. The model produces data consistent with observations on the San Andreas fault and the Palmdale area. 891013 Relationship between textures and sliding motion of experimentally deformed fault gouge: application to fault zone behaviour Moore, D E; Summers, R; Byerlee, J D Key Questions in Rock Mechanics: Proc 29th US Symposhun, Minneapolis, 13-15 June 1988 PI03-110. Publ Rotterdam." A A Balkema, 1988 Clay rich and quartzofeldspathic fault zone materials were studied in the laboratory to investigate differences between samples that slide stably and those which show stick slip motion. Transition between sliding modes was correlated with Iocalisation of shear and increase in angle between boundary and Reidel shears. A possible earthquake mechanism proposed, based on these differences, involves localisation Of slip creating the potential for large stress build ups under favourable circumstances. This hypothesis is to be tested experimentally.
Frost action, permafrost and frozen ground See also." 891093, 891378
891010 Strain melting, the wetting transition and seismic instabilities Lomnitz-Adler, J Geophys J 1/94, NI. July 1988. P125-130 A fault mechanism is developed which involves wetting of a pre-existing planar defect by a molten phase of microscopic dimensions, lowering frictional forces on almost planar regions. For fault regions of finite thickness, this results in an order of magnitude increase in creep rate, which initiates macroscopic melting in the fault region. This mechanism can explain low stress drops and small heat flow anomalies near superficial faults, cutoff in seismicity with depth, and nonlinear deformation near the fault trace.
891014 Subsoil investigation of ice lensing at the Calgary, Canada, frost heave test facility Carlson, L E; Nixon, J F Can Geotech J 1/25, N2, May 1988, P307-319 Several frost heave mitigation modes were studied in a chilled pipeline frost heave test facility. These included deeper burial to increase pressure on the frost front below the pipe and replacement of the silty soil around the pipe with gravel for a noninsulated pipe. Frost heave at the deep burial and gravel sections was less than at the control section. Other pipe sections tested the effects of insulation of the pipe on long term frost heave and effects of replacing silt around an insulated
1989 Pergamon Press plc. Reproduction not permitted