理想砂井地基径向弹黏塑性固结分析

饱和黏土变形的非线性和流变特性已被人们所逐渐认识。为进一步探讨该特性对砂井地基固结过程的影响,引入考虑时间效应的统一硬化(UH)本构模型描述土体骨架弹黏塑性变形关系,在Barron砂井固结理论的基础上,重新推导砂井径向固结方程,并给出方程的隐式有限差分格式。通过与Berry基于压缩指数的显式数值解对比,验证本文计算方法的有效性。探讨了UH模型参数和渗透指数对砂井径向固结的影响。数值结果表明:黏性土的粘滞性使得固结前期砂井地基内部出现了孔压升高现象,并延缓了固结中后期砂井地基内孔隙水压力的整体消散。同时,随着初始超固结参数R₀、回弹指数C_s的增大或渗透指数C_k的减小,此现象变得更加明显。

Analysis on Radial Elastic Visco-Plastic Consolidation of Ideal Sand-drained Ground

The nonlinear and rheological properties of saturated clay deformation have been gradually recognized.In order to further investigate the influence of these characteristics on the consolidation process of sand-drained ground,the unified-hardening(UH) constitutive model considering time effect was introduced to describe the elastic visco-plastic deformation relationship of the soil skeleton.Basis on the Barron's consolidation theory,the radial consolidation equation of sand-drained ground was re-deduced,and its numerical analysis was performed using the implicit finite difference scheme.The validity of this method is verified by comparing the explicit numerical solution of Berry's based on the compression index.Then the effects of UH model parameters and permeability index on the radial consolidation process were discussed.The numerical results indicate that the viscosity of clay soil not only makes the pore water pressure rise inside the sand-drained ground in the early stage of consolidation,but also delays the overall dissipation of pore water pressure in the middle and late stage of consolidation.Meanwhile,with the increase of the initial over consolidated parameter R₀and the rebound index C_s or the decrease of the permeability index C_k,the phenomenon becomes more obvious.