浅覆土矩形顶管施工对邻近基桩的影响规律研究

为研究因顶管施工的挤土效应对邻近高架桥基桩水平变形的影响，以无锡地铁青石路段1号地铁出入口为例，采用MIDAS GTS软件模拟浅覆土条件下矩形顶管顶进施工，计算在不同的顶管顶进距离、基桩与隧道间净距，以及不同的顶管开挖面顶进压力、管节与土体间摩阻力条件下的基桩水平变形。结果表明： 1）矩形顶管顶进施工时会造成邻近基桩发生沿顶进方向和垂直顶进方向的水平变形，且以沿顶进方向的水平变形为主； 2）不同于其他矩形顶管工程，浅覆土条件下基桩受顶管施工的影响范围约为隧道外4D（D为矩形顶管长边尺寸），基桩的水平变形随着净距的减小而增大，且当净距小于2D时，其水平变形呈非线性快速增加； 3）相对于开挖面顶进压力，管节与土体之间的摩阻力对基桩的影响更大，其水平位移变化可分为线性增长和非线性增长2个阶段。

Influence of Rectangular Pipe Jacking Construction on Adjacent Foundation Piles under Shallow Buried Soil

To investigate the influence of horizontal deformation of foundation pile adjacent to viaduct caused by soil squeezing effect of pipe jacking construction, a case study is conducted on the entrance and exit section of No.1 metro on Qingshi road in Wuxi, China. Furthermore, the Midas GTS software is used to simulate the construction process of rectangular pipe jacking under the condition of shallow buried soil, and the horizontal deformation of foundation piles under various jacking distance, clear space between the foundation pile and the tunnel, jacking pressure of the excavation face, and friction between pipe joint and soil is calculated. The results reveal the following: (1) The adjacent piles will deform along the jacking direction and vertical jacking direction during the jacking construction of rectangular pipe jacking, and the deformation is mainly along the jacking direction. (2) The influence range of pile jacking construction under the condition of shallow buried soil is about 〖WT〗4D 〖WT５《TNR》〗outside the tunnel 〖WT〗(D 〖WT５《TNR》〗is the long side size of rectangular pipe jacking), and the horizontal deformation of pile increases with a decrease in clear space; when the clear space is less than 〖WT〗2D, 〖WT５《TNR》〗the horizontal deformation of the pile increases nonlinearly and rapidly. (3) The friction between the pipe joint and the soil has a greater impact on the foundation pile than jacking pressure of the excavation face, and the increase of the horizontal displacement can be divided into two stages, i.e., linear and nonlinear growth.