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Dynamic consolidation for a clay foundation with sand package
97A based on an 8-node quadrilateral element. Whilst of an exploratory nature, the study has shown that a reasonable impression of time-dependent anchor behaviour can be obtained using numerical analysis. 873096 Dynamic consolidation for a clay foundation with sand package Qian, J H; Zhao, W B; Qian, Z Proc 5th International Conference on Numerical Methods in Geomechanies, Nagoya, 1-5 April 1985 VI, P637-642. Publ Rotterdam: A. A. Balkema, 1985 After installing a sand package system, the soft clay foundation in a northern China harbour was improved by the dynamic consolidation method. Firstly, dynamic consolidation tests in the laboratory are described. Results of both loading and unloading modulus, and the empirical pore pressure formula of the soft clay samples extracted from the harbour foundations were obtained. Secondly, the finite difference method was employed for solving both the shock wave in the clay foundation due to impact on the ground surface and the dissipation of pore pressure by sand package. Finally, the calculated results of vertical and horizontal displacements, and pore pressures at intervals of time were compared with field measurements. By theoretical computations and field measurements, it was concluded that sand package is an effective measure, otherwise dynamic consolidation is not valid for soft clay foundation.
with overconsolidation ratio. Results are presented from two onshore and two offshore clays, and compared with other direct and indirect determinations of the coefficient of lateral stress for normally consolidated and overconsolidated clays, for loading, unloading and reloading.
Dynamic properties 873100 Stability of saturated sands under earthquake loading Wang Tian Song; Liu Ying Comput Geotech V2, N5, 1986, P309-326 An analytical method to evaluate the stability of saturated sands under earthquake loading is presented. Dynamic porewater pressure ratios in saturated sand and the critical porewater pressure ratios beyond which the sands will tend to an unstable state are computed. These ratios are used to establish criteria for evaluating stability and liquefaction.
873101 Effects of damping on the interpretation of geophysical measurements Abbiss, C P Geotechnique V36, N4, Dec 1986, P565-580
Both finite difference schemes and finite element schemes have been presented for calculating the effective stress and displacement in a soft foundation when acted on by vacuum preloading. Results calculated with these methods are in good agreements with data observed in field tests~
Measurements of damping in situ as a function of strain are described. Three different methods were used: hammer damping, resonance of an embedded pipe, and hysteresis due to cyclic loading. All three methods show distinct values of damping in boulder clay, which indicates clearly that an elastic behaviour must be taken into account. There is some evidence that damping is dependent on time as well as strain. When moduli derived from shear wave velocities are used to calculate settlement of loaded pads, corrections involving time dependence proportional to damping are required. Measurements were used to produce two class A predictions of the time dependent settlement of loaded pads that were within 20% of the observed values. Suitable viscoelastic models are considered. Auth.
873098 Time-deflection behaviour of a Hgid underreamed anchor in a deep clay layer Small, J C; Booker, J R University of Sydney School of Civil and Mining Engineering research report R522, March 1986, 27P
873102 Response of poroelastic halfspace to steady-state harmonic surface tractions Halpern, M C; Christiano, P Int d Num Anal Meth Geomeeh I"10, N6, Nov-Dec 1986, P609-632
The problem of consolidation of the soil around an anchor is examined. The analysis is carried out by applying a Hankel and a Laplace transform to the field variables in order to simplify the governing equations. The final solutions are obtained by numerically inverting both the Hankel and Laplace transformations. The unknown contact stress between the anchor and the soil, and the unknown flows in the plane of the anchor are approximated as a series of simple functions with unknown coefficients. By determining the coefficients of the terms in the series, the complete solution may be found. These results are used to examine the accuracy of some finite element solutions to the problem.
Traditionally, most formulations of dynamic halfspace problems have represented the material as either an elastic or a viscoelastic solid. Herein the counterpart of Lamb's elastodynamic problem is reformulated and solved for a liquidsaturated poroelastic halfspace using Biot's theory of poroelasticity. The responses of the solid and fluid phases due to steady-state harmonic concentrated loads applied to each phase at the surface are evaluated. The solutions are presented over a broad range of permeabilities and are compared to solutions to Lamb's problem for equivalent drained and undrained solids. Methodology is then introduced by which these results are treated as Green functions for the solution of a mixed boundary-value problem, namely, for the response of the poroelastic halfspace to steady-state harmonic vertical motion of a rigid,massless plate. It is observed that small differences exist among overall compliance functions for a drained solid, an undrained solid, and a liquid-saturated porous halfspace. Use of the poroelastic model permits the distribution between effective skeletal normal stresses and fluid stresses to be determined. Auth.
873097 Numerical analysis of soft foundation vacuum preloading Chen, H; Yon, S W Proc 5th International Conference on Numerical Methods in Geomechanics, Nagoya, 1-5 April 1985 111, P643-647. Publ Rotterdam: A. A. Balkema, 1985
873099 Coefficient of lateral stress from oedometer cell Dyvik, R; Lacasse, S; Martin, R T Norw Geotech Inst Publ N163, 1986, 4P An oedometer ring, specially made for the measurement of lateral stresses in soil specimens, has been successfully used to study the variation in the coefficient of earth pressure at rest
© 1987 Pergamon Journals Ltd. Reproduction not permitted
with overconsolidation ratio. Results are presented from two onshore and two offshore clays, and compared with other direct and indirect determinations of the coefficient of lateral stress for normally consolidated and overconsolidated clays, for loading, unloading and reloading.
Dynamic properties 873100 Stability of saturated sands under earthquake loading Wang Tian Song; Liu Ying Comput Geotech V2, N5, 1986, P309-326 An analytical method to evaluate the stability of saturated sands under earthquake loading is presented. Dynamic porewater pressure ratios in saturated sand and the critical porewater pressure ratios beyond which the sands will tend to an unstable state are computed. These ratios are used to establish criteria for evaluating stability and liquefaction.
873101 Effects of damping on the interpretation of geophysical measurements Abbiss, C P Geotechnique V36, N4, Dec 1986, P565-580
Both finite difference schemes and finite element schemes have been presented for calculating the effective stress and displacement in a soft foundation when acted on by vacuum preloading. Results calculated with these methods are in good agreements with data observed in field tests~
Measurements of damping in situ as a function of strain are described. Three different methods were used: hammer damping, resonance of an embedded pipe, and hysteresis due to cyclic loading. All three methods show distinct values of damping in boulder clay, which indicates clearly that an elastic behaviour must be taken into account. There is some evidence that damping is dependent on time as well as strain. When moduli derived from shear wave velocities are used to calculate settlement of loaded pads, corrections involving time dependence proportional to damping are required. Measurements were used to produce two class A predictions of the time dependent settlement of loaded pads that were within 20% of the observed values. Suitable viscoelastic models are considered. Auth.
873098 Time-deflection behaviour of a Hgid underreamed anchor in a deep clay layer Small, J C; Booker, J R University of Sydney School of Civil and Mining Engineering research report R522, March 1986, 27P
873102 Response of poroelastic halfspace to steady-state harmonic surface tractions Halpern, M C; Christiano, P Int d Num Anal Meth Geomeeh I"10, N6, Nov-Dec 1986, P609-632
The problem of consolidation of the soil around an anchor is examined. The analysis is carried out by applying a Hankel and a Laplace transform to the field variables in order to simplify the governing equations. The final solutions are obtained by numerically inverting both the Hankel and Laplace transformations. The unknown contact stress between the anchor and the soil, and the unknown flows in the plane of the anchor are approximated as a series of simple functions with unknown coefficients. By determining the coefficients of the terms in the series, the complete solution may be found. These results are used to examine the accuracy of some finite element solutions to the problem.
Traditionally, most formulations of dynamic halfspace problems have represented the material as either an elastic or a viscoelastic solid. Herein the counterpart of Lamb's elastodynamic problem is reformulated and solved for a liquidsaturated poroelastic halfspace using Biot's theory of poroelasticity. The responses of the solid and fluid phases due to steady-state harmonic concentrated loads applied to each phase at the surface are evaluated. The solutions are presented over a broad range of permeabilities and are compared to solutions to Lamb's problem for equivalent drained and undrained solids. Methodology is then introduced by which these results are treated as Green functions for the solution of a mixed boundary-value problem, namely, for the response of the poroelastic halfspace to steady-state harmonic vertical motion of a rigid,massless plate. It is observed that small differences exist among overall compliance functions for a drained solid, an undrained solid, and a liquid-saturated porous halfspace. Use of the poroelastic model permits the distribution between effective skeletal normal stresses and fluid stresses to be determined. Auth.
873097 Numerical analysis of soft foundation vacuum preloading Chen, H; Yon, S W Proc 5th International Conference on Numerical Methods in Geomechanics, Nagoya, 1-5 April 1985 111, P643-647. Publ Rotterdam: A. A. Balkema, 1985
873099 Coefficient of lateral stress from oedometer cell Dyvik, R; Lacasse, S; Martin, R T Norw Geotech Inst Publ N163, 1986, 4P An oedometer ring, specially made for the measurement of lateral stresses in soil specimens, has been successfully used to study the variation in the coefficient of earth pressure at rest
© 1987 Pergamon Journals Ltd. Reproduction not permitted