Theoretical solutions for consolidation of composite foundation considering non-uniform distribution of initial excess pore water pressure and radial-vertical combined flows in a granular column

Abstract

In this paper, the consolidation problem of composite foundation is studied to consider the non-uniform distribution of initial excess pore water pressure along depth and the radialvertical combined flows in a granular column. The general theoretical solutions are obtained by introducing a new initial condition. The consolidation theory of composite foundation advanced herein is distinguished from the existing ones for that the initial excess pore water pressure is non-uniformly along depth in the foundation, and the radial flow in granular columns is considered. And thus, the three special cases for non-uniform distribution of initial excess pore water pressure which including the uniform, triangle and inverted triangle distribution are discussed, and the corresponding particular solutions of average excess pore water pressure and average degree of consolidation are derived. According to these analytical solutions, the relevant programs are coded. The influence of a few major factors on the consolidation course of composite ground is investigated, and the results are prepared in graph forms. Therefore, it is shown that the distribution of initial excess pore water pressure has obvious influence on the consolidation of composite ground with single drainage boundary; the consolidation of composite foundation is accelerated with the increase in the ratio of the top initial excess pore pressure to the bottom one in the foundation; the consolidation rate is at its maximum when the initial excess pore pressure distributes in the form of a inverted triangle and at its minimum when the initial excess pore pressure distributes in the form of a triangle; the smaller the value of k h /k s and n, that is, the smaller the degree of soil disturbance and the drainage radius of a granular column is, the faster the consolidation rate is; the higher the compression modulus of a granular column is, the faster the consolidation rate is.