管幕钢顶管顶进施工力学效应分析

Mechanical Effect Analysis of Pipe Jacking Construction with Steel Pipe Roof

为研究管幕钢顶管顶进施工过程钢管产生的力学效应,建立顶管-泥浆-复合地层数值模型,分析钢顶管内力及泥浆界面受力特征。研究结果表明:顶管在顶入时主要受到泥浆正向压力和剪切作用,沿轴向顶管轴力尾部至前端逐渐减小,竖向顶管轴力下部略大于上部,从而形成微小转动弯矩致使尾部略微上浮;在同一横截面,顶管下部轴力大于上部轴力,轴向上顶管尾部轴力大于前端轴力,顶管顶入所需荷载随顶入长度增加而增大,增长曲线呈非线性,随顶入深度增大,增幅逐渐减少;受泥浆力学特性和地层围压影响,泥浆剪应力由顶管顶部至底部逐渐增大,顶管顶入距离越长,泥浆剪应力极值越小。

In order to study the mechanical effect of steel pipe during pipe jacking construction,a numerical model of pipe jacking-mud-composite formation is established,and the internal force of steel pipe jacking and the stress characteristics of mud interface are analyzed.The research results show that:pipe jacking is mainly subjected to the forward pressure and shear action of mud during jacking,and the axial force of pipe jacking along the axial direction gradually decreases from the tail to the front end,and the axial force of pipe jacking along the vertical direction is slightly greater than that at the upper part,thereby forming a small rotational bending moment to make the tail float slightly;on the same cross section,the axial force at the lower part of the pipe jacking is greater than that at the upper part;in the axial direction,the axial force at the end of pipe jacking is greater than the axial force at the front end.The load required for pipe jacking increases with the increase of jacking length,and the growth curve is nonlinear.With the increase of jacking depth,the increase gradually decreases;affected by the mechanical properties of the mud and the confining pressure of the formation,the shear stress of the mud gradually increases from the top to the bottom of the pipe jacking.The longer the jacking distance,the smaller the extreme value of mud shear stress.