ANALYSIS OF ONE-DIMENSIONAL LARGE STRAIN CONSOLIDATION OF SOFT CLAY WITH THRESHOLD GRADIENT
LI Chuanxun1，XU Chao1，XIE Kanghe2
(1. Faculty of Civil Engineering and Mechanics，Jiangsu University，Zhenjiang，Jiangsu 212013，China；
2. Research Center of Coastal and Urban Geotechnical Engineering，Zhejiang University，Hangzhou，Zhejiang 310058，China)
Abstract：Threshold gradients and large deformation of thick soft soil may have been realized by researchers. However，the theory of large strain consolidation of soft clay with threshold gradient has rarely been reported. Supposing the constant coefficient of volume compressibility and the square relationship between coefficient of permeability and void ratio，the governing equation and solution conditions of large strain consolidation of soft clay with threshold gradient are developed in Lagrangian coordinates，in which excess pore water pressure serves as a variable. Finite difference method is adopted to obtain the solution for the problem of moving boundary which is induced by threshold gradients，and the reliability of numerical results is verified by comparing the numerical solutions under tiny threshold gradient(10－5) with analytical solutions in case of Darcy?s flow law. Thus，an effective method is provided to solve the problem of moving boundary. Finally，the influence of dimensionless variable R on consolidation behavior and the difference of consolidation behavior between large-strain and small-strain assumptions are analyzed，and the results show that the value of dimensionless variable R influences the final flow front location，the moving rate of flow front location and the dissipation rate of excess pore water pressure. The larger the value of R is，the slower the moving rate of flow front location is，and the slower the dissipation rate of excess pore water pressure is. The larger the value of R is，the larger the residual excess pore water pressure is, and the less the final settlement of soil layer is. The dissipation rate of excess pore water pressure with large-strain assumption is faster than that with small-strain assumption；furthermore，the residual excess pore water pressure with large-strain assumption is less than that with small-strain assumption. This consolidation behavior results in that the final settlement of foundation with large-strain assumption is larger than that with small-strain assumption.
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2015, Vol. 34 
