旋喷群桩复合地基承载特性的数值分析

Numerical analysis of bearing characteristics of composite subgrade reinforced by chemical churning pile groups

旋喷桩加固软土地基在各种地基处理工程中得到了广泛应用。对旋喷桩的研究多数集中在其施工工艺的改进上,或者针对单桩的承载特性进行研究,而对旋喷群桩的承载特性则研究不多。根据工程实际情况,采用基于MIDAS-GTS的三维有限元分析技术,通过改变旋喷群桩的布置方式、桩弹性模量、桩长、桩径、桩距等设计参数及桩-土接触面等参数对旋喷群桩复合地基承载特性的影响进行了研究。研究表明:旋喷桩加固软土地基主要减小了地表至桩底深度范围内土体的竖向沉降,对桩底下方的土体沉降基本无影响;提高旋喷桩桩径及材料强度会提高复合地基承载能力;不同旋喷桩布置方式、桩-土之间是否设置Goodman接触面单元对地基承载能力基本无影响。

The method of soft soil subgrade reinforcement with chemical churning pile is used more and more in projects of subgrade treatment.At present,the researches about chemical churning pile usually focus on improvement in construction techniques or bearing characteristics of single pile.But research about bearing characteristics of chemical churning pile groups is not much.Based on MIDAS-GTS three-dimensional finite element analysis,the influence of design parameters on bearing characteristics of chemical churning pile groups is studied.These design parameters of chemical churning pile include layout,elastic modulus,length,diameter of piles,and distance between piles,the parameters of interface between piles and soil.The results show that the vertical settlement of soil within the range between surface and pile bottom is reduced in soft soil subgrade reinforced by chemical churning piles;but the method has little effect on the vertical settlement of soil under pile bottom.Larger pile diameter and higher material strength can improve the bearing capacity of composite subgrade.But different layouts of chemical churning piles and whether to set up Goodman interface element have little influence on bearing capacity of composite subgrade.