基于变形控制的密排管幕顶管施工顺序优化分析

Optimization Analysis of Pipe Jacking Construction Sequence with Dense Tube Curtain Based on Deformation Control

管幕可以为隧道施工提供强度较大的超前支护。为择优选择管幕施工顺序,减少管幕施工对地表沉降影响,以合肥大连路隧道工程为例,采用三维数值分析方法,考虑“先下排后上排连续顶入/先上排后下排连续顶入、先上排后下排间隔顶入”3种顶入顺序,研究不同管幕施工顺序对地表沉降的影响规律。研究结果表明:(1)上排顶管形成的土拱效应对下排起到保护作用,故最佳施工顺序为:先施工管幕上排顶管,再施工两侧及下排顶管;(2)由于顶管端头的高压旋喷加固和端部结构约束,管幕顶进引起的地表变形呈现端部小,中间大的特征;(3)侧排顶管不影响沉降叠加区最大沉降值,横向地表沉降曲线类似于S形,地表沉降最大值为12.7 mm,最终影响范围为24 m。

The pipe curtain could provide advanced support with high strength for the tunnel.In order to select the optimal construction sequence of pipe curtain and reduce the impact of pipe curtain construction on surface settlement,taking the Hefei Dalian Road Tunnel project as an example,the three-dimensional numerical analysis method was used to study the impact of different pipe curtain construction sequences on surface settlement by considering the three jacking sequences,inlcuding upper and lower row sequence,continuous jacking and interval jacking.The research results show that:(1)The soil arch effect formed by the top row of pipe jacking plays a protective role on the bottom row,and the best construction sequence is:construct the top row of pipe jacking on the pipe curtain firstly,then construct the two sides of the pipe curtain and the bottom row of pipe jacking;(2)The high pressure rotary jet grouting at the end of pipe jacking strengthens the soil and the end structure constraints,and the surface deformation caused by pipe curtain jacking shows the characteristics of small end settlement and large middle settlement;(3)Side row pipe jacking does not affect the maximum settlement value in the settlement superposition area;The horizontal surface settlement curve is similar to the S-shape,with the maximum surface settlement of 12.7 mm and the final impact range of 24 m.