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Rotational components of surface strong ground motion
290A 896007 Geotechnical survey of the Piraeus marl Costopoulos, S D
896011 Rotational components of surface strong ground motion Oliveira, C S; Bolt, B A
Soils Found V29, N1, March 1989, P138-150
Earthq Engng Struct Dynam V18, N4, April 1989, P517-526
Existing data are evaluated to identify the degradation mechanism of Piraeus marl due to weathering processes. Large numbers of laboratory tests are re-evaluated using correlations between selected index properties of the marl. Results are discussed.
Rotational components of seismic waves have been estimated from data collected by the SMART-1 strong motion array in Taiwan. Rotational components of the strain field were computed for five earthquakes of magnitude 5.7-7.8 and epicentral distances 6-84km. Measured values of pure rotation and rocking are in agreement with the spatial coherency structure observed in earthquakes. Much additional information is required to help understand response of structures to torsional seismic components.
896OO8 Erosion of unsurfaced earth and gravel roads Kumapley, N K Proc Ninth Regional Conference for Africa on Soil Mechanics and Foundation Engineering, Lagos, September 1987 V1,
P397-404. Publ Rotterdam: A A Balkema, 1987 Rill and gully erosion of unsurfaced roads in Ghana is a serious problem. The mechanics of soil erosion is briefly reviewed, and the effect on erosion of water, slope length and grade, and rainfall and runoff is discussed. Decomposed phyllites are widespread in Ghana. This clayey silt has much reduced strength when wet and is highly erodible. Erosion cannot be totally eliminated, but the potential of synthetic chemical soil stabilisers and lime stabilisers is discussed.
Earthquake mechanisms and effects See also: 896438
896012 Aseismic-seismogenic coupling for a long strike-slip fault Husseini, M I
Geophys J 1/97, N3, June 1989, P391-407 The quasistatic stage of a 2D mechanical model of a large strike slip earthquake stage is described in terms of the seismogenic depth, thickness of the crust, remote stress, and shear modulus of the crust. The dynamic earthquake stage is reached when energy release rate equals twice the shear fracture energy at the base of the seismogenic part of the fault. The dynamic earthquake stage is also described in terms of the previously considered parameters and depth of coseismic slip. 896013 Physical model for earthquakes. 3. Thermodynamical approach and its relation to nonclassical theories of nucleation Rundle, J B
J Geophys Res V94, NB3, March 1989, P2839-2855 896009 Transient scattering of elastic waves by dipping layers of arbitrary shape. Part 1: antiplanc strain model Eshraghi, H; Dravinski, M
Earthq Engng Struet Dynam V18, N3, March 1989, P397-415 Scattering of elastic waves by two dimensional multilayered dipping sediments of arbitrary shape embedded in an elastic half space is analysed using a boundary method. Both harmonic and transient incident wave fields are considered. Transient response is evaluated from the steady state solution using the fast Fourier transform. The sediments may cause significant changes to local amplification of strong ground motion. Motion can be affected by scattered surface waves in the sediments. Surface ground motion depends on nature of the incident wave, type of subsurface irregularity and location of the observation point. 896010 Transient scattering of elastic waves by dipping layers of arbitrary shape. Part 2: plane strain model Eshraghi, H; Dravinski, M
Earthq Engng Struct Dynam V18, N3, March 1989, P417-434 Scattering of elastic waves by dipping layers of arbitrary shape embedded in an elastic half space is investigated using a boundary method. A computationally effective model is used in which the unknown scattered wave field is expressed in terms of wave functions which satisfy the equations of motion and appropriate boundary conditions at infinity. Results show locally large amplifications may result from scattering of waves by dipping layers. Amplification depends on nature of the incident wave, location of observation point, geometry of subsurface irregularity, impedance contrast between layers and component of displacement being observed.
A theory of earthquakes, sliding and frictional slip consistent with fundamental thermodynamic considerations is presented. All systems tend towards a state of minimum Helmholtz free energy. Local, metastable equilibrium is possible. Earthquakes arise when the sudden decay of a fault system to a state closer to global, absolute equilibrium occurs. 896014 Cohesive zone model for dynamic shear faulting based on experimentally inferred constitutive relation and strong motion source parameters Ohnaka, M; Yamashita, J
J Geophys Res 1/94, NB4, April 1989, P4089-4104 When the earthquake source is modelled as a dynamically propagating shear crack with a rupture front near which the concentration of stresses is involved, the stress singularity of linear elastic fracture mechanics is avoided if the cohesive zone concept is introduced, whereby strength degrades with ongoing slip behind the propagating crack tip. A physically reasonable constitutive model, based on laboratory observations, of cohesive stress and slip displacement is proposed to describe dynamic breakdown processes during earthquake events. Predictions of the model agree well with experimental simulations and can explain interactions between strong motion source parameters for earthquakes. 896015 Development of stochastic ground movement: study of SMART-I array data Loh, C H; Su, G W; Yeh, C S Soil Dynam Earthq Engng I/8, NI, Jan 1989, P22-31 An attempt is made to estimate possible effects of source and local soil parameters on ground motion spectra. A stochastic soil amplification function is first developed. Soil deposit depth, soil density and shear modulus, and corner frequency
~" 1989 Pergamon Press pic. Reproduction not permitted
896011 Rotational components of surface strong ground motion Oliveira, C S; Bolt, B A
Soils Found V29, N1, March 1989, P138-150
Earthq Engng Struct Dynam V18, N4, April 1989, P517-526
Existing data are evaluated to identify the degradation mechanism of Piraeus marl due to weathering processes. Large numbers of laboratory tests are re-evaluated using correlations between selected index properties of the marl. Results are discussed.
Rotational components of seismic waves have been estimated from data collected by the SMART-1 strong motion array in Taiwan. Rotational components of the strain field were computed for five earthquakes of magnitude 5.7-7.8 and epicentral distances 6-84km. Measured values of pure rotation and rocking are in agreement with the spatial coherency structure observed in earthquakes. Much additional information is required to help understand response of structures to torsional seismic components.
896OO8 Erosion of unsurfaced earth and gravel roads Kumapley, N K Proc Ninth Regional Conference for Africa on Soil Mechanics and Foundation Engineering, Lagos, September 1987 V1,
P397-404. Publ Rotterdam: A A Balkema, 1987 Rill and gully erosion of unsurfaced roads in Ghana is a serious problem. The mechanics of soil erosion is briefly reviewed, and the effect on erosion of water, slope length and grade, and rainfall and runoff is discussed. Decomposed phyllites are widespread in Ghana. This clayey silt has much reduced strength when wet and is highly erodible. Erosion cannot be totally eliminated, but the potential of synthetic chemical soil stabilisers and lime stabilisers is discussed.
Earthquake mechanisms and effects See also: 896438
896012 Aseismic-seismogenic coupling for a long strike-slip fault Husseini, M I
Geophys J 1/97, N3, June 1989, P391-407 The quasistatic stage of a 2D mechanical model of a large strike slip earthquake stage is described in terms of the seismogenic depth, thickness of the crust, remote stress, and shear modulus of the crust. The dynamic earthquake stage is reached when energy release rate equals twice the shear fracture energy at the base of the seismogenic part of the fault. The dynamic earthquake stage is also described in terms of the previously considered parameters and depth of coseismic slip. 896013 Physical model for earthquakes. 3. Thermodynamical approach and its relation to nonclassical theories of nucleation Rundle, J B
J Geophys Res V94, NB3, March 1989, P2839-2855 896009 Transient scattering of elastic waves by dipping layers of arbitrary shape. Part 1: antiplanc strain model Eshraghi, H; Dravinski, M
Earthq Engng Struet Dynam V18, N3, March 1989, P397-415 Scattering of elastic waves by two dimensional multilayered dipping sediments of arbitrary shape embedded in an elastic half space is analysed using a boundary method. Both harmonic and transient incident wave fields are considered. Transient response is evaluated from the steady state solution using the fast Fourier transform. The sediments may cause significant changes to local amplification of strong ground motion. Motion can be affected by scattered surface waves in the sediments. Surface ground motion depends on nature of the incident wave, type of subsurface irregularity and location of the observation point. 896010 Transient scattering of elastic waves by dipping layers of arbitrary shape. Part 2: plane strain model Eshraghi, H; Dravinski, M
Earthq Engng Struct Dynam V18, N3, March 1989, P417-434 Scattering of elastic waves by dipping layers of arbitrary shape embedded in an elastic half space is investigated using a boundary method. A computationally effective model is used in which the unknown scattered wave field is expressed in terms of wave functions which satisfy the equations of motion and appropriate boundary conditions at infinity. Results show locally large amplifications may result from scattering of waves by dipping layers. Amplification depends on nature of the incident wave, location of observation point, geometry of subsurface irregularity, impedance contrast between layers and component of displacement being observed.
A theory of earthquakes, sliding and frictional slip consistent with fundamental thermodynamic considerations is presented. All systems tend towards a state of minimum Helmholtz free energy. Local, metastable equilibrium is possible. Earthquakes arise when the sudden decay of a fault system to a state closer to global, absolute equilibrium occurs. 896014 Cohesive zone model for dynamic shear faulting based on experimentally inferred constitutive relation and strong motion source parameters Ohnaka, M; Yamashita, J
J Geophys Res 1/94, NB4, April 1989, P4089-4104 When the earthquake source is modelled as a dynamically propagating shear crack with a rupture front near which the concentration of stresses is involved, the stress singularity of linear elastic fracture mechanics is avoided if the cohesive zone concept is introduced, whereby strength degrades with ongoing slip behind the propagating crack tip. A physically reasonable constitutive model, based on laboratory observations, of cohesive stress and slip displacement is proposed to describe dynamic breakdown processes during earthquake events. Predictions of the model agree well with experimental simulations and can explain interactions between strong motion source parameters for earthquakes. 896015 Development of stochastic ground movement: study of SMART-I array data Loh, C H; Su, G W; Yeh, C S Soil Dynam Earthq Engng I/8, NI, Jan 1989, P22-31 An attempt is made to estimate possible effects of source and local soil parameters on ground motion spectra. A stochastic soil amplification function is first developed. Soil deposit depth, soil density and shear modulus, and corner frequency
~" 1989 Pergamon Press pic. Reproduction not permitted