褥垫层参数对刚性桩复合地基受力特性的影响分析

Analysis on Influence of Mattress Layer Parameters on Stress Characteristics of Rigid Pile Composite Foundations

本文运用MIDAS GTS岩土有限元分析软件,通过数值试验分析,研究了刚性桩复合地基在不同厚度、不同弹性模量褥垫层的条件下,其承载力特性的影响。分析结果表明,褥垫层弹性模量一定时,随褥垫层厚度的增加,桩身分担荷载的比例迅速减小,而桩间土分担荷载的比例却逐渐增大,表现为桩土应力比随垫层厚度增加而降低的特点。另一方面,随着垫层弹性模量的减小桩尖刺入褥垫层量增大,导致桩土荷载分担比减小。褥垫的设置可以起到显著改变桩土应力比的作用,提高桩间土土体承载能力的发挥,并且可以削弱群桩的“边角效应”,使刚性桩承担荷载更加均匀。综合分析褥垫层分配桩土应力及桩身受荷模式,褥垫厚度在0.2~0.3m,弹性模量在60~90MPa的范围内比较合适。

In this paper,the bearing capacity characteristics of rigid pile composite foundations under different thicknesses and different modulus of elasticity mattress layer are studied by numerical experiments using MIDAS GTS geotechnical finite element analysis software.The analysis results show that when the elastic modulus of the mattress layer is constant,the proportion of the pile body loading decreases rapidly with the increasing thickness of the mattress layer,while the proportion of the pile soil loading gradually increases,which is manifested as the pile soil stress ratio decreases with the increasing thickness of the layer.On the other hand,with the decrease of the elastic modulus of the layer,the amount of pile tip penetration into the mattress layer increases,resulting in a decrease in the pile soil loading proportion.The setting of the mattress layer can significantly change the pile soil stress ratio,improve the bearing capacity of soil between piles,and weaken the“corner effect”of pile groups,so that rigid piles bear loads more uniformly.Based on the comprehensive analysis of the pile soil stress and pile body loading mode that the mattress layer distributes,it is appropriate to set the thickness of the mattress layer as 0.2~0.3 m and the elastic modulus within the range of 60~90 MPa.