考虑自重影响的饱和土体一维复杂非线性固结研究

根据宁波软土室内压缩试验数据,得到渗透系数及有效应力与孔隙比的非线性关系.考虑土体自重影响,采用以孔隙比为控制变量的一维大变形固结方程,应用偏微分有限元软件FLEXPDE,研究了不同压缩指数与渗透指数比值下土体有效应力和超静孔压在固结过程中沿深度的分布规律.试验结果和数值分析表明：考虑土体复杂非线性相对于假定固结系数及其他参数在固结过程中保持不变,计算结果更符合实际.在压缩指数与渗透指数比值不等于1的情况下,两种方法计算结果差别明显.为了真实反映土体固结过程中有效应力和超静孔压的分布,应考虑土体渗透性及压缩性的非线性变化.

Study on properties of one-dimensional complex nonlinear consolidation considering self-weight of saturated soils

The nonlinear equations of permeability coefficient and effective stress were derived as functions of void ratio from compression test data of Ningbo soft clay.Based on one-dimensional nonlinear large strain consolidation equation using void ratio as a control variable,the effect of self-weight of soil on consolidation was taken into account.The behavior of self-weight consolidation is strongly nonlinear.It is difficult to find analytical solutions to its controlling equation.Partial differential finite element software FLEXPDE was used to solve the consolidation equation.Distributions of effective stress and excess pore water pressure with depth were presented under conditions of different ratios between compression index and permeability index.The numerical results considering complex nonlinearity of soil were in better agreement with the laboratory test data than those obtained under the assumptions for constant consolidation coefficient and other parameters during consolidation.If the compression-permeability index ratio is not equal to 1.0,the results using these two methods differ significantly.In this case,the nonlinearity of permeability and compressibility should be considered in order to understand the real distributions of effective stress and excess pore water pressure with depth during consolidation.