Behaviour of the Soft Clay Ground under Tank

Firstly, the stress-strain relationship and anisotropies in strength and in stiffness of Jinshan clay are studied by the K0 consolidated triaxial tests and unconfined compression tests. The effects of the relative stiffness between tank and subsoil and the anisotropy of soft clay on the settlements are studied by finite element method.Secondly, based on the laboratory test results, the equations of nonlinear elastic parameters are developed, in which the effects of the initial anisotropic stress state and inherent anisotropy of the clay are considered. It is shown that the tangent modulus of the soil depends upon the mean effective stress and the strength mobilization, whereas the tangent Poissou's ratio depends upon the strength mobilization only. By means of the strength mobilization, the stiffness of soil may be related with the strength of soil.Finally, the consolidation process of the soft clay ground under two oil tanks, 10000m3 and 30000m3, in volume respectively, during the period of water test are analyzed based on Biot's consolidation theory by means of finite element method, the stiffness of the superstructure, ring wall and fills beneath tank being taken into account. The calculated settlements and pore water pressures agree well with the values obtained from the field measurement.