群桩基础非线性有限元强度折减法极限分析

受到静载荷试验条件限制,群桩基础的极限载荷是通过单桩载荷试验极限值修正来确定群桩基础的极限载荷,所判定的极限载荷值往往缺少客观性。文中建立了多变量群桩基础承载力泛函数,首先基于加载过程中桩土系统的岩土材料强度参数与载荷施加参数具有相互匹配的同时性关系,引入强度折减系数,提出了基础安全储备系数,用以表示所施加外载荷与真实极限荷载的比值。其次,极限条件下群桩的桩端材料发生塑性变形,桩土系统从一种稳定状态快速进入另一种稳定状态的突变关系,在荷载位移关系上具体表现为拐点后出现一铅直线段,据此建立了群桩基础有限元强度折减法极限载荷判定条件。最后使用ANSYS软件进行了螺旋群桩基础的三维有限元强度折减法的工程应用分析,当外载荷207 800 N时的安全储备系数为1.16,极限荷载计算值为241 048 N小于静载荷试验判定极限荷载值249 400 N,误差3.35%,验证了群桩基础强度折减系数法的可行性。

Strength Reduction Method of No-linear FEM Limit Analysis for Pile Group Foundation

Confined by the condition of static loading test,the ultimate load of pile group is modified by the ultimate load of static loading test of a pile,so the estimated ultimate value lacks objectivity.The variables of universal function of bearing capacity of pile group are put up.First,based on one another matching parameters of strength for geotechnical material according to simultaneity relation in the forced pile foundation,and induced the strength reduction factor,the safety storage factor(SSF) is put up,w...