含下卧层复合地基固结的简化分析

Simplified Solution to Composite Foundation with Substratum

将加固区桩体和桩周土体径向整体作为一个研究对象,从而避开单独考虑因施工造成的涂抹作用的影响.根据单元体排出水量等于体积变化量的关系,用平均超孔隙水压力的概念推导出含下卧层复合地基的固结简化方程.通过改进加固区和下卧层区接触面的边界条件、考虑应力集中效应并结合初始边界条件得到了含下卧层复合地基中超孔隙水压力随时间变化的解析式,提出了反映沉降量大小的整体固结度计算方法.该方法可直接求得不同深度桩体和桩周土的平均超孔隙水压力和平均固结度,也可得到复合地基整体固结度.利用有限元法对解析解进行了对比分析,并通过参数变化的探讨研究了含下卧层复合地基的固结性状的变化规律.

With pile and its surrounding soil in radial direction studied as a whole, the effect of the coating caused by construction is not necessary to be considered independently. According to the equivalent of seepage discharge to volume change, a simplified consolidation formula of composite foundation with substratum is derived from the concept of average excess pore water pressure. Based on the improved boundary condition of the interface between the reinforced body and the substratum, and a study of the effect of stress concentration and the initial and boundary conditions, the analytic solution, which can reflect the relationship of the excess pore water pressure with consolidation time, is acquired and the degree of consolidation which can reflect settlement is obtained as well. This method can be used to obtain the average excess pore water pressure and average percent consolidation of the pile and its surrounding soil, and the average percent consolidation of the entire composite foundation. The feasibility of this analysis solution is testified by finite element method. The consolidation characteristic of composite foundation with substratum is studied through the calculation and analysis of different parameters.