大尺寸矩形顶管始发井反力墙数值模拟与监测

Numerical Simulation and Monitoring of Reaction Wall of Launching Shaft for Large Rectangular Pipe Jacking

为分析顶推反力荷载对墙后土体位移、应力、孔隙水压力的影响,以及不同反力加载深度、土体弹性模量、加固体厚度、加固体深度对墙后土体水平位移的影响,建立顶管顶进过程中工作井反力墙稳定性的动态三维有限元分析模型,研究结果表明:1)反力荷载仅影响对应的部分土体区域,反力加载区域附近的土体水平位移变化大;2)地面除0 m附近出现较大沉陷外,其他位置均表现为隆起,隆起呈平行"波痕"状;3)反力荷载只是改变墙后土体的土压力类型,没有改变土压力的分布形态;4)顶推反力的大小对土体孔压的变化影响轻微;5)反向顶推力合力点深度及土体弹性模量对土体侧向位移影响较大;6)加固体深度和厚度对土体侧向位移影响轻微。

In this paper, a dynamic three-dimensional finite element analysis model for the stability of the reaction wall during pipe jacking is established, so as to analyze the influence of the jacking reaction load on the displacement, stress and pore water pressure of the soil behind the wall and that of soil elastic modulus, solid thickness and solid depth on the horizontal displacement of soil behind the wall. The results show that:( 1) The reaction load only affects the corresponding part of the soil area, and the horizontal displacement of the soil around the reaction load area varies greatly.(2) Except for a large subsidence of ground right above reaction wall, the other areas show uplifts with parallel wave shape.(3) The reaction load only changes the type of earth pressure behind the wall, and does not change the distribution of earth pressure.(4) The jacking reaction load affects the soil pore pressure little.(5) The depth of the combined force point of the reverse jacking force and the elastic modulus of the soil have a greater effect on the lateral displacement of the soil.(6) The solid depth and thickness affect the lateral displacement of soil little.