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Measurement of dynamic soil characteristics (in French)
98A 873103 Effective stress analysis of seismic site respome. Short communication Prevost, J H lnt J Num Anal Meth Geomech VIO, N6, Nov-Dec 1986, P653-665 A procedure is presented which allows site response analyses to be performed with any general multidimensional finite element analysis package. Numerical results which corroborate the theory are presented. Also, as an illustration of the procedure, results of an effective stress analysis for the seismic response and liquefaction of a horizontally layered saturated sand deposit are presented. Auth.
873104 Crack tensor and its relation to wave velocity auisotropy in jointed rock masses Oda, M; Yamabe, T; Kamemura, K lnt J Rock Mech Min Sci V23, N6, Dec 1986, P387-397 Wave velocity anisotropy of three discontinuous materials (gypsum plaster samples with artificial cracks, granites with microcracks and jointed granites) is reported in detail with special emphasis on the relation between the anisotropy and crack geometry represented by the crack tensor. Such relations are useful for extracting information concerning the crack geometry of jointed rock masses from geophysical exploration.
873105 Weak elastic anisotropy Thomsen, L J Geopkys II51, NIO, Oct 1986, P1954-1966 Most bulk elastic media are weakly anisotropic. The equations governing weak anisotropy indicate that a certain anisotropic parameter, an awkward combination of elastic parameters, controls most anisotropic phenomena of importance in exploration geophysics, some of which are non-negligible even when the anisotropy is weak. Elementary facts about anisotropy are reviewed and the simplified angular dependence of wave velocities appropriate to weak anisotropy is presented. The anisotropic parameters identified have been used to analyse several common problems in petroleum geophysics. Discussion and conclusions are noted.
873106 Pore fluids and frequency-dependent wave propagation in rocks Jones, T D J Geophys V51, NIO, Oct 1986, P1939-1953 Laboratory measurements show seismic phase velocity and attenuation are dependent upon the fluid saturation and the product of frequency and pore fluid viscosity, with a peak in attenuation between the seismic and sonic bands. The dominant mechanism by which seismic energy is dissipated in the upper crust is local viscous fluid flow in pores of small aspect ratio. This behaviour is modelled as a series of linear viscoelastic elements with a narrow distribution of relaxation times, where velocity and attenuation are related through the Hilbert transform. Results indicate that the frequency content, phase spectrum, and velocity may be strong indicators of the type of pore fluid in a formation. Alternatively,if the type of pore flu!d is known, these attributes could be used to monitor temperature changes of a formation. 55 refs.
873107 Low strain dynamic properties of artificially cemented sand Acar, Y B; El-Tahir, A E J Geotech Engng Div ASCE Vl12, Nll, Not, 1986, P10011015 Torsional resonant column tests are conducted to study the effect of artificial cementation on low strain dynamic properties of Monterey No. 0 sand. Artificially cemented specimens are prepared using 1, 2, and 4 0 Portland cement by weight. It is determined that the maximum shear modulus increased and damping ratio decreased with an increase in the degree of cementation. The maximum dynamic shear moduli increased due to corresponding increases in stiffness coefficients. The stiffness ratio defined as the stiffness of cemented to uncemented specimens varied with the degree of cementation and density. 873108 Moduli and damping factors for dynamic analyses of cohesionless soils Seed, H B; Wong, R T; Idriss, I M; Tokimatsu, K J Geotech Engng Div ASCE VI12, Nll, Nov 1986, P10161032 Data are presented concerning the shear modulus and damping ratios of sands and gravelly soils as determined by laboratory and field tests. A simple relationship is proposed to relate the shear modulus of a cohesionless soil to a modulus stiffness coefficient, which is a soil property and depends on the characteristics of the soil, and the effective mean principle stress at any point in the soil. Values for the modulus at low strains are suggested, and it is shown that these values for sands can be estimated from the standard penetration resistance of the sand. Values for gravels are generally greater than those for sands by factors ranging from 1.35-2.5. Suggestions are made for determining the variation of shear modulus with shear strain and the damping ratios for both sandy and gravelly soils. Auth. 873109 Pore pressure in ocean-floor sands under random waves Rahman, M S; Layas, F M Marine Geotechnol V6, N4. 1986, P341-358 A general procedure for the analysis of pore water pressure in ocean floor sands under the action of random waves is presented. Using a simple linear model for the generation of pore pressure and incorporating the effect of simultaneous dissipation, a formulation of expected damage is developed in a stochastic framework. The formulation is incorporated into the computer program POLIQA and used to evaluate expected sea floor damage associated with the build up of pressure in terms of depth, permeability and time. 873110 Measurement of dynamic soil characteristics (In French) Luong, M P Rev Fr Geotech N37, 1986, P17-28 Laboratory and in situ tests to measure the dynamic modulus and damping ratio of soils over a wide range of deformation amplitudes of interest for the earthquake resistant design of engineering structures are examined. Measurement of ultrasonic or Rayleigh wave velocities and the determination of the required constants from these measurements, and the resonant column test are considered in some detail. The strain rate effects due to shock or explosive loading are also studied.
© 1987 Pergamon Journals Ltd. Reproduction not permitted
873104 Crack tensor and its relation to wave velocity auisotropy in jointed rock masses Oda, M; Yamabe, T; Kamemura, K lnt J Rock Mech Min Sci V23, N6, Dec 1986, P387-397 Wave velocity anisotropy of three discontinuous materials (gypsum plaster samples with artificial cracks, granites with microcracks and jointed granites) is reported in detail with special emphasis on the relation between the anisotropy and crack geometry represented by the crack tensor. Such relations are useful for extracting information concerning the crack geometry of jointed rock masses from geophysical exploration.
873105 Weak elastic anisotropy Thomsen, L J Geopkys II51, NIO, Oct 1986, P1954-1966 Most bulk elastic media are weakly anisotropic. The equations governing weak anisotropy indicate that a certain anisotropic parameter, an awkward combination of elastic parameters, controls most anisotropic phenomena of importance in exploration geophysics, some of which are non-negligible even when the anisotropy is weak. Elementary facts about anisotropy are reviewed and the simplified angular dependence of wave velocities appropriate to weak anisotropy is presented. The anisotropic parameters identified have been used to analyse several common problems in petroleum geophysics. Discussion and conclusions are noted.
873106 Pore fluids and frequency-dependent wave propagation in rocks Jones, T D J Geophys V51, NIO, Oct 1986, P1939-1953 Laboratory measurements show seismic phase velocity and attenuation are dependent upon the fluid saturation and the product of frequency and pore fluid viscosity, with a peak in attenuation between the seismic and sonic bands. The dominant mechanism by which seismic energy is dissipated in the upper crust is local viscous fluid flow in pores of small aspect ratio. This behaviour is modelled as a series of linear viscoelastic elements with a narrow distribution of relaxation times, where velocity and attenuation are related through the Hilbert transform. Results indicate that the frequency content, phase spectrum, and velocity may be strong indicators of the type of pore fluid in a formation. Alternatively,if the type of pore flu!d is known, these attributes could be used to monitor temperature changes of a formation. 55 refs.
873107 Low strain dynamic properties of artificially cemented sand Acar, Y B; El-Tahir, A E J Geotech Engng Div ASCE Vl12, Nll, Not, 1986, P10011015 Torsional resonant column tests are conducted to study the effect of artificial cementation on low strain dynamic properties of Monterey No. 0 sand. Artificially cemented specimens are prepared using 1, 2, and 4 0 Portland cement by weight. It is determined that the maximum shear modulus increased and damping ratio decreased with an increase in the degree of cementation. The maximum dynamic shear moduli increased due to corresponding increases in stiffness coefficients. The stiffness ratio defined as the stiffness of cemented to uncemented specimens varied with the degree of cementation and density. 873108 Moduli and damping factors for dynamic analyses of cohesionless soils Seed, H B; Wong, R T; Idriss, I M; Tokimatsu, K J Geotech Engng Div ASCE VI12, Nll, Nov 1986, P10161032 Data are presented concerning the shear modulus and damping ratios of sands and gravelly soils as determined by laboratory and field tests. A simple relationship is proposed to relate the shear modulus of a cohesionless soil to a modulus stiffness coefficient, which is a soil property and depends on the characteristics of the soil, and the effective mean principle stress at any point in the soil. Values for the modulus at low strains are suggested, and it is shown that these values for sands can be estimated from the standard penetration resistance of the sand. Values for gravels are generally greater than those for sands by factors ranging from 1.35-2.5. Suggestions are made for determining the variation of shear modulus with shear strain and the damping ratios for both sandy and gravelly soils. Auth. 873109 Pore pressure in ocean-floor sands under random waves Rahman, M S; Layas, F M Marine Geotechnol V6, N4. 1986, P341-358 A general procedure for the analysis of pore water pressure in ocean floor sands under the action of random waves is presented. Using a simple linear model for the generation of pore pressure and incorporating the effect of simultaneous dissipation, a formulation of expected damage is developed in a stochastic framework. The formulation is incorporated into the computer program POLIQA and used to evaluate expected sea floor damage associated with the build up of pressure in terms of depth, permeability and time. 873110 Measurement of dynamic soil characteristics (In French) Luong, M P Rev Fr Geotech N37, 1986, P17-28 Laboratory and in situ tests to measure the dynamic modulus and damping ratio of soils over a wide range of deformation amplitudes of interest for the earthquake resistant design of engineering structures are examined. Measurement of ultrasonic or Rayleigh wave velocities and the determination of the required constants from these measurements, and the resonant column test are considered in some detail. The strain rate effects due to shock or explosive loading are also studied.
© 1987 Pergamon Journals Ltd. Reproduction not permitted