软黏土层一维有限应变固结的超静孔压消散研究

根据土力学固结理论计算分析软黏土层固结过程的超静孔隙水压力值，确定软黏土体固结过程的强度增长，对排水固结法处理软土地基至关重要。软黏土层固结过程中土体变形较大时，有限应变固结理论和小应变固结理论计算分析软黏土固结所得结果差异较大。利用非线性有限元法及程序，通过对软黏土层固结工程算例的计算结果分析，研究了有限应变固结理论和小应变固结理论计算分析软黏土层一维固结超静孔压值消散的差异；探讨了软黏土体一维固结过程中，几何非线性、土体渗透性变化和压缩性变化对超静孔隙水压力消散的影响。研究结果表明，当土体的变形较大时，有限应变固结理论计算出的超静孔压要比小应变固结理论得到的值消散的更快。考虑土体固结过程中渗透性的变化时，超静孔压消散变慢；可用软黏土渗透性变化指数ck 反映渗透性变化对超静孔压消散的影响，渗透性变化指数ck值越小、超静孔压消散越慢。固结过程中软黏土压缩性的大小及变化也影响超静孔压的消散，可用软黏土的压缩指数cc反映固结过程中压缩性的大小及变化对超静孔压消散的影响，软黏土的压缩指数cc越小，固结过程软黏土层中的超静孔压消散越快。

Research on dissipation of excess pore water pressure in one-dimensional finite strain consolidation of soft clays

It is very important for soft clay foundation treatment by consolidation that to calculate and analyse dissipation of excess pore water pressure in the process of soft clay consolidation according to the consolidation theory of soil mechanics, and to estimate increase of shear strength of soft clay. When the deformation of soft clay layer in consolidation is large, the consolidation analysis results of finite strain consolidation theory are different from those of small strain consolidation theory. Using the nonlinear finite element method and program and analyzing computational results of engineering examples of soft clay layer consolidation, this paper studies the differences of dissipation of excess pore water pressure which are obtained from finite strain consolidation theory and small strain consolidation theory, and studies effects of geometrical nonlinearity, variable permeability and variable compressibility on dissipation of excess pore water pressure in the process of one-dimensional soft clay layer consolidation. The research results show that the dissipation of excess pore water pressure obtained from finite strain consolidation theory is faster than that obtained from small strain consolidation theory，as the deformation of soft clay layer in consolidation is large. The dissipation of excess pore water pressure becomes slower when the variation of permeability of soft clay is taken into account; the permeability change index ck can represent the effect of variation of permeability on the dissipation of excess pore water; the smaller the ck is, the slower the dissipation of excess pore water is. The value and the variation of compressibility of soft clay also have effect on the dissipation of excess pore water pressure is; the compressibility change index ck can represent the effect of the value and the variation of permeability on the dissipation of excess pore water pressure; the smaller the cc is, the faster the dissipation of excess pore water pressure is.