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.