变附加应力条件下考虑桩体二维井阻作用的复合地基固结解析理论研究

Analytical study on consolidation of composite ground considering twodimensional well resistance under time and depth dependent stresses

通过在现有解的形式基础上增加一个二次多项式,提出一种新的复合地基固结解的形式及解答方法,推导得到地基附加应力既随时间变化也随深度变化条件下考虑桩体竖向及径向二维井阻作用的散体材料桩复合地基固结解析解,通过退化、与已有解的比较等方法对解进行分析验证。结果表明,现有的瞬时荷载下考虑桩体径竖向渗流的解、考虑桩体竖向渗流与变形协调的解、太沙基一维固结解等都是本文解的特例,这说明本文解的正确合理性。地基加载历时越长,固结越慢;地基底部附加应力越小,固结越快;考虑桩体径竖向二维井阻时地基固结比只考虑竖向井阻时慢,桩径比越小,桩体渗透系数越小,两者的差异越大。本文解的表达形式及解答方法,为复合地基固结度的求解提供一种新的思路,发展和完善了现有的复合地基固结理论。

A new solution for consolidation of composite ground was proposed by adding a quadratic polynomial to the previous solution. The analytical consolidation solution of composite ground considering the effect of two-dimensional well resistance was obtained for granular column under the condition of the additional ground stress varied with time and depth. The solution was compared with the previous simplified analytical expressions. The results show that many previous expressions are the special cases of the solutions deduced in this paper, such as the solution considering the effect of two-dimensional well resistance under the effect of instantaneous loading, the solution considering the seepage and vertical deformation of pile body as well as the Terzaghi one-dimensional consolidation solution, which indicate the correctness and reasonability of the solution obtained. The consolidation rate is increased with the increasing of loading rate and decreased with the increasing of additional stress at the bottom of the ground. The consolidation rate considering the two-dimensional well resistance of the columns is slower than the one considering only the vertical well resistance. The difference of the consolidation rates under the conditions of these two considerations is increased with the decreasing of permeability coefficient of column and the radius ratio of the influence zone to the column. The solution proposed in this paper provides a new idea for solving the consolidation process of composite foundation and contributes to the development and improvement of consolidation theory of composite ground.