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Liquefaction and flow failure during earthquakes
84A 942186 Elastic waves through a simulated fractured medium Hsu, C J; Schoenberg, M
Geophysics V58, NT. July 1993, P964-977 Block specimens of roughened lucite plates held together in a press were prepared to represent rock containing parallel fractures. Ultrasonic wave velocities were measured parallel, normal, and oblique to the fractures. Velocity data are related to moduli of an equivalent anisotropic medium and the extent to which the medium parameters fit the linear slip (L-S) model of Schoenberg is examined. Fracture system parameters and isotropic background parameters are extracted from the data and dependence of fracture system parameters and independence of background parameters on static stress across the fractures is seen. 942187 Reasonable choices for material constants in seismic modeling Rosenbaum, J H
Geophysics V58, N7, July 1993, P978-986 In exploration geophysics it is often necessary to make educated guesses about unknown elastic and attenuation parameters of the formation when interpreting results. An extension is presented of the long-wavelength-equivalent-medium theory to the anelastic case in order to derive default options and stability criteria, which requires minimal information input, appears reasonable for many geological materials, and reduces to a proper description in the case of isotropy. 942188 Weak elastic anisotropy and the tube wave Norris, A N; Sinha, B K
Geophysics V58, NS, Aug 1993, P1091-1098 Influence of anisotropy on tube wave speed is examined using a perturbation method. Where anisotropy is weak, it is shown that speed can be expressed in terms of an effective shear modulus for an equivalent isotropic formation. Using in addition expressions for speeds of SH and quasi-SV waves along the borehole axis, 3 of the 5 elastic constants of a transversely isotropic formation tilted at a known angle with respect to the borehole axis can be obtained. A fourth constant can be derived using an expression for quasi-P wave speed along the borehole axis. 942189 Evaluation of the drop bar test for concrete and rock quality Charlie, W A; Ross, C A; Skinner, M M; Burleigh, J B
Geotech Test J V16. N3, Sept 1993, P350-364 The empirical method of assessing rock quality from the sound it produces when struck by a pick or steel bar is reexamined. The sound and the stress produced in the drop bar are evaluated. Instrumenting the drop bar extends the capability of the test and reduces its subjectivity. The work suggests that sound frequency and peak stress produced by dropping a steel bar can be used to evaluate in situ dynamic properties and, indirectly, in situ static properties of foundation materials. Limitations are discussed. 942190 Liquefaction and flow failure during earthquakes Ishihara, K
Geotechnique V43, N3, Sept 1993, P351-415 The 33rd Rankine Lecture. The triggering conditions for and consequences of earthquake-induced liquefaction of soils are discussed. The former is examined with respect to liquefaction analysis, note being taken of the onset condition governed by cyclic strength. Post-seismic liquefaction analysis, for which
residual strength is of major importance, is then considered, together with induced settlement and its prediction. Methods of estimating and interpreting residual strength from laboratory tests and correlations with SPT and CPT field data are described. It is shown that these correlations are consistent with many cases of flow failure associated with large earthquakes. 942191 Short-crested wave-induced soil response in a porous seabed of infinite thickness Hsu, J R C; Jeng, D S; Tsai, C P
Int J Nura Anal Meth Geomech V17, N8, Aug 1993. P553576 Short crested waves reflected off structures are conducive to scour of the bed in front of the structure. The resulting pore pressures and effective stresses induced by these reflected waves are derived analytically for an unsaturated anisotropic soil matrix of infinite depth in a 3-dimensional domain. The equations are verified against available solutions. The effects of wave obliquity, relative water depth, soil stiffness, and soil permeability on induced pore pressure are discussed. 942192 Project VELACS - control test results Arulanandan, K; Scott, R F
J Geotech Engng Div ASCE Vl19. N8, Aug 1993, P12761292 The Verification of Liquefaction Analysis by Centrifuge Studies (VELACS) project is an inter-university project ultimately aimed at studying the mechanisms of liquefaction-induced failures and testing numerical procedures used in their analysis. on the basis of dynamic model centrifuge tests. Initial work to evaluate dependence of test results on equipment and operator is described. Results from standard tests in 8 different centrifuges are compared. Although there is some scatter, they are close enough for use in analysis validation exercises. 942193 Pattern recognition approach to evaluation of soil liquefaction potential using piezocone data Yiqiang, D; Berrill, J B
Soil Dynam garthq Engng VI2, N2. 1993, P91-101 A pattern recognition approach to soil liquefaction prediction is presented in which the state of any soil layer at a level ground site is represented by a pattern in 7-dimensional feature space and the soil can be classified as liquefiable or nonliquefiable cohesive or cohesionless soil. Liquefaction potential is assessed according to the probability of the pattern belonging to each of these classes. Training patterns have been developed on the basis of piezocone and maximum ground acceleration data from sites in New Zealand. A Parzen window approach and a parameter estimation approach to pattern recognition are examined. 942194 Effect of confining pressure on dynamic soil properties using improved transfer function estimators Amini, F
Sail Dynam Eartlui Engng V12, N3, 1993, P145-147 The effect of variation of confining pressure on shear modulus and damping values for a soil under random excitation conditions, obtained using three new transfer function estimators (H2, H3 and H4) and the conventional estimator (HI), is discussed. Shear moduli are consistent and effectively independent of confining pressure and difference between damping values obtained by the various estimators decreases with increasing confining pressure.
Geophysics V58, NT. July 1993, P964-977 Block specimens of roughened lucite plates held together in a press were prepared to represent rock containing parallel fractures. Ultrasonic wave velocities were measured parallel, normal, and oblique to the fractures. Velocity data are related to moduli of an equivalent anisotropic medium and the extent to which the medium parameters fit the linear slip (L-S) model of Schoenberg is examined. Fracture system parameters and isotropic background parameters are extracted from the data and dependence of fracture system parameters and independence of background parameters on static stress across the fractures is seen. 942187 Reasonable choices for material constants in seismic modeling Rosenbaum, J H
Geophysics V58, N7, July 1993, P978-986 In exploration geophysics it is often necessary to make educated guesses about unknown elastic and attenuation parameters of the formation when interpreting results. An extension is presented of the long-wavelength-equivalent-medium theory to the anelastic case in order to derive default options and stability criteria, which requires minimal information input, appears reasonable for many geological materials, and reduces to a proper description in the case of isotropy. 942188 Weak elastic anisotropy and the tube wave Norris, A N; Sinha, B K
Geophysics V58, NS, Aug 1993, P1091-1098 Influence of anisotropy on tube wave speed is examined using a perturbation method. Where anisotropy is weak, it is shown that speed can be expressed in terms of an effective shear modulus for an equivalent isotropic formation. Using in addition expressions for speeds of SH and quasi-SV waves along the borehole axis, 3 of the 5 elastic constants of a transversely isotropic formation tilted at a known angle with respect to the borehole axis can be obtained. A fourth constant can be derived using an expression for quasi-P wave speed along the borehole axis. 942189 Evaluation of the drop bar test for concrete and rock quality Charlie, W A; Ross, C A; Skinner, M M; Burleigh, J B
Geotech Test J V16. N3, Sept 1993, P350-364 The empirical method of assessing rock quality from the sound it produces when struck by a pick or steel bar is reexamined. The sound and the stress produced in the drop bar are evaluated. Instrumenting the drop bar extends the capability of the test and reduces its subjectivity. The work suggests that sound frequency and peak stress produced by dropping a steel bar can be used to evaluate in situ dynamic properties and, indirectly, in situ static properties of foundation materials. Limitations are discussed. 942190 Liquefaction and flow failure during earthquakes Ishihara, K
Geotechnique V43, N3, Sept 1993, P351-415 The 33rd Rankine Lecture. The triggering conditions for and consequences of earthquake-induced liquefaction of soils are discussed. The former is examined with respect to liquefaction analysis, note being taken of the onset condition governed by cyclic strength. Post-seismic liquefaction analysis, for which
residual strength is of major importance, is then considered, together with induced settlement and its prediction. Methods of estimating and interpreting residual strength from laboratory tests and correlations with SPT and CPT field data are described. It is shown that these correlations are consistent with many cases of flow failure associated with large earthquakes. 942191 Short-crested wave-induced soil response in a porous seabed of infinite thickness Hsu, J R C; Jeng, D S; Tsai, C P
Int J Nura Anal Meth Geomech V17, N8, Aug 1993. P553576 Short crested waves reflected off structures are conducive to scour of the bed in front of the structure. The resulting pore pressures and effective stresses induced by these reflected waves are derived analytically for an unsaturated anisotropic soil matrix of infinite depth in a 3-dimensional domain. The equations are verified against available solutions. The effects of wave obliquity, relative water depth, soil stiffness, and soil permeability on induced pore pressure are discussed. 942192 Project VELACS - control test results Arulanandan, K; Scott, R F
J Geotech Engng Div ASCE Vl19. N8, Aug 1993, P12761292 The Verification of Liquefaction Analysis by Centrifuge Studies (VELACS) project is an inter-university project ultimately aimed at studying the mechanisms of liquefaction-induced failures and testing numerical procedures used in their analysis. on the basis of dynamic model centrifuge tests. Initial work to evaluate dependence of test results on equipment and operator is described. Results from standard tests in 8 different centrifuges are compared. Although there is some scatter, they are close enough for use in analysis validation exercises. 942193 Pattern recognition approach to evaluation of soil liquefaction potential using piezocone data Yiqiang, D; Berrill, J B
Soil Dynam garthq Engng VI2, N2. 1993, P91-101 A pattern recognition approach to soil liquefaction prediction is presented in which the state of any soil layer at a level ground site is represented by a pattern in 7-dimensional feature space and the soil can be classified as liquefiable or nonliquefiable cohesive or cohesionless soil. Liquefaction potential is assessed according to the probability of the pattern belonging to each of these classes. Training patterns have been developed on the basis of piezocone and maximum ground acceleration data from sites in New Zealand. A Parzen window approach and a parameter estimation approach to pattern recognition are examined. 942194 Effect of confining pressure on dynamic soil properties using improved transfer function estimators Amini, F
Sail Dynam Eartlui Engng V12, N3, 1993, P145-147 The effect of variation of confining pressure on shear modulus and damping values for a soil under random excitation conditions, obtained using three new transfer function estimators (H2, H3 and H4) and the conventional estimator (HI), is discussed. Shear moduli are consistent and effectively independent of confining pressure and difference between damping values obtained by the various estimators decreases with increasing confining pressure.