886181 Liquefaction-induced compaction and settlement of sand during earthquakes

283A _ behaviour, and analysis of the data shows a relation between ratio of resistivity of permafrost in its frozen and unfrozen state, and extent of freezing of interstitial water. 886175 Low-frequency tube waves in permeable rocks Chang, S K; Liu, H L; Johnson, D L Geophysics V53, N4. April 1988, P519-527 Low-frequency tube waves in permeable boreholes are of interest since their propagation depends on in situ rock permeability. Low frequency asymptotics are used to unify two approaches describing tube waves. One is White’s derivation in which low-frequency tube-wave velocity and attenuation are expressed as functions of frequency. The second is the full solution of tube-wave properties based on Biot theory. The low frequency tube wave expression derived is similar to White’s, but corrected to include elasticity of the solid frame around the borehole. It gives solutions close to the full solution below 3OOHz. 886176 Centrifuge liquefaction tests in a laminar box Hushmand, B; Scott, R F; Crouse, C B Geotechnigue V38, N2, June 1988, P253-262 A box made of freely moving aluminium lamellae was constructed to allow shear distortion in soil to develop unimpeded by the container. Accelerometers, displacement transducers, and pore pressure sensors were installed in saturated and unsaturated sand samples in the box, which were subject to earthquake excitation in a centrifuge. Results obtained under controlled conditions were compared with various calculation methods for liquefaction prediction. 886177 Axisymmetric Lagrangian technique for predicting earth penetration h&ding penetrator response Schwer, L E; Rosinsky, R; Day, J Int J Num Anal Meth Geomech V12. N3, May-June 1988, P235-262 A computational technique for earth penetration is presented which incorporates a deformable target model and a deformable penetrator, both discretized to represent expected terradynamic and structural responses. Time dependent terradynamic to penetration interaction is achieved by using a sliding interface between the two models. Target to penetrator interaction is included in one calculation in a continuous and consistent manner. Calculated penetrations are compared with results of large scale field tests using reinforced concrete targets. 886178 Pseudo-plane strtin analysis of wave propagation problems a~Mng from detonations of explosives in cylindrical boreholes Ang, K K; Valliappan, S Int J Num Anal Meth Geomech V12, N3. May-June 1988, P301-322 Three dimensional finite element analysis of wave propagation is very expensive, and often approximate modelling in two dimensions is used as a cheaper alternative. It is demonstrated that the conventional two dimensional plane strain analysis produces erroneously excessive results, due to inability to correctly model rapid attenuation of amplitude of outwardly propagating waves. A pseudo-plane strain concept is introduced to overcome this problem. Results of its application are presented. 0

886179 Two-dimensional direct boundary integral method for elastodynamics Crouch, S L; Tian, Y lnt J Rock Mech Min Sci V2.5, N3, June 1988, P149-158 The mathematical and numerical development of a boundary element method for two dimensional elastodynamic problems, based on a time-domain formulation of the two dimensional boundary integral method, is presented. Two examples illustrate use of the model. The first is for a suddenly pressurised circular hole in an initially unstressed infinite plate, whilst the second is for two circular holes, one of which is suddenly pressurised. The model seems to handle the wave reflections properly if a sufficiently small time step is chosen.

886180 Regression models for evaluating liquefaction probability Liao, S S C; Veneziano, D; Whitman, R V J Geotech Engng Div ASCE VI14. N4, April 1988, P389-411 Statistical techniques developed to calculate the probability of liquefaction as a function of earthquake load and soil resistance parameters are presented. Results are obtained based on 218 case histories of liquefaction and non-liquefaction. Binary regression is used to develop 4 models of liquefaction behaviour. Two are local, using a form of cyclic stress ratio as a measure of earthquake intensity, and 2 are source, in which earthquake intensity is replaced by earthquake source characteristics. The models are applied to field data to illustrate their different features.

886181 Liquefaction-induced compaction and settlement of sand during earthquakes Nagase, H; Ishihara, K Soils Found V28, NI, March 1988, P65-76 Two series of simple shear tests, one in uni-directional, the other in multi-directional loading conditions, were undertaken on loose, medium dense and dense sand samples, employing 12 irregular time histories of motion from major earthquakes. After load application, generated pore water pressures were allowed to dissipate and volumetric strain measured. Results show that reconsolidation volumetric strain correlates uniquely with magnitude of maximum shear strain induced during irregular loading.

886182 Liquefaction strength of sands subjected to sustained pressure Tatsuoka, F; Kato, H; Kimura, M; Pradhan, T B S Soils Found V28. Nl, March 1988. P119-I31 Cyclic undrained triaxial tests were conducted on sand specimens consolidated under sustained pressure or overconsolidated, and the results compared. Results show that strength increased after 68 days under sustained pressure, equivalent to the increase obtained by overconsolidation with OCR at 2. Increase in strength due to long term consolidation and overconsolidation is shown to be a similar function of axial plastic strain sustained during consolidation history, suggesting the strength increase is due to a similar mechanism in each. The sands containing fines show a larger increase in strength than those without.

1988 Pergamon Press plc. Reproduction

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