路堤分级填筑条件下不排水端承桩复合地基固结分析

利用均质化技术将桩土复合地基均质化为均质土地基,考虑桩土相互作用,给出均质化后复合地基的等价压缩模量。在等应力假定基础上,建立了路堤分级填筑条件下不排水端承桩复合地基固结方程,给出复合地基固结的解析解,并与有限元法解答进行了对比;对不排水端承桩复合地基固结性状作了分析。研究发现,不排水端承桩复合地基固结速率远大于天然地基,在其他条件相同时,瞬时加荷情况下复合地基固结速率最大。复合地基固结速率随置换率、桩土模量比及加荷速率的增加而增大。复合地基置换率存在最佳值,超过最佳置换率后,复合地基固结速率随置换率增加增幅较小。

Consolidation Analysis of Composite Ground with Undrained Penetrating Piles under Stage Embankment Construction

Soft ground improved by penetrating piles was treated as a homogeneous soil deposit by means of homogenization technique.The equivalent compression modulus of the composite ground was proposed with consideration of mutual interaction between piles and surrounding soil.Based on the assumption of equal stress condition,consolidation equation of composite ground with undrained penetrating piles under stage embankment construction was established,and analytical solutions for degree of consolidation of the composite ground were presented.The validity of the proposed method was conformed through comparison between the present analytical solutions and the finite element analyses.Consolidation characteristics of the composite ground were investigated.It is shown that(1) consolidation rate of natural ground is much slower than that of the composite ground;(2) the consolidation rate of the composite ground under instantaneous loading is faster than that under the same conditions;(3) consolidation rate of the composite ground increases with the increase of replacement ratio,compression modulus ratio between pile and its surrounding soil,and loading rate;(4) there is an optimum replacement ratio for the composite ground,in excess of which the consolidation rate of the composite ground changes hardly with increasing replacement ratio.