A development of pore water pressure model for multi-directional cyclic shearing of different clays

Tran Thanh Nhan

In the proceedings of: GeoVancouver 2016: 69th Canadian Geotechnical Conference

Session: GEOHAZARDS - IV Earthquakes and Tsunamis

ABSTRACT: This paper is to develop a model for cyclic shear-induced excess pore water pressure in clays subjected to undrained strain-controlled uni-directional and multi-directional cyclic shearing. By using the multi-directional cyclic simple test apparatus, several series of cyclic shear tests were carried out on normally consolidated Kaolinite clay, Tokyo bay clay and Kitakyushu clay under the various cyclic shear conditions such as uni-direction and multi-direction at phase difference = 200, 450, 700 and 900, cyclic shear strain amplitude ( = 0.05% - 2.0%), and the number of cycles n = 200. It is indicated from the experimental results that, irrespective of the undrained cyclic shearing conditions, the characteristic of pore water pressure during undrained cyclic shear is evidently affected by the plasticity of clayey soil. The higher the of the clay, the smaller the threshold cumulative shear strain for pore water pressure buildup (G*tp) and the slower rate of pore water pressure accumulation, leading to the lower level of cyclic shear-induced pore water pressure. In addition to the cumulative shear strain (G*), the plasticity index (Ip) is incorporated into an estimation method of pore water pressure as a function of its experimental constants. The excess pore water pressure generated by the undrained uni-directional and multi-directional cyclic shears was confirmed to be estimated precisely by the developed model for clays with a wide limits.

RÉSUMÉ: différentes argiles soumises non drainé déformation contrôlée unidirectionnelles et multidirectionnelles cyclique cisaillement. Au mavec plusieurs directions de cisaillement cyclique (Uni-direction et multi-direction à la différence de phase = 200, 450, 700 et 900) et des amplitudes de déformation en cisaillement cyclique ( = 0.05% - 2.0%), et le nombre de cycles est fixé comme n = 200. Des résultats expérimentaux, il est indiqué que, quel que soit le non drainé cyclique de cisaillement des conditions, la caractéristique de la pression interstitielle au cours du cisaillement cyclique est évidemment affectée par la plasticité des sols argileux. Limite de plus la A(G*tpe de cisaillement cyclique. En plus de la déformation de cisaillement cumulative (G*Ippression interstitielle excès sous non drainé unidirectionnelles et .

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