Simulation analysis of a shallow-covered large cross-section rectangular pipe-jacking crossing highway

Abstract

In this paper, based on a large cross-section shallow overburden rectangular pipe jacking project, using numerical simulation method to analyze the impact of pipe jacking construction on the highway, taking into account the positive jacking force of pipe jacking machine head on the soil, grouting pressure of slurry sleeve, setting of isolation steel pipe concrete curtain, friction-reducing slurry sleeve and other factors. The main conclusions are as follows: (1) the front jacking force is between the theoretical Rankine active earth pressure and the Rankine passive earth pressure. With the increase of jacking force, the road surface appears different degrees of uplift. When the jacking force is set between the active earth pressure and the static earth pressure, the uplift rate is the largest. In order to facilitate the construction control, it is suggested to control according to the theoretical static earth pressure; (2) the theoretical grouting control pressure The top of the pipe jacking is taken as the overlying water and soil pressure at the top of the mud jacket, and the bottom of the pipe jacking is taken as the sum of the overlying water and soil pressure and the hydro-static pressure of the mud sleeve. Based on the analysis of 0.8 times, 1.0 times and 1.2 times control grouting pressure, with the increase of grouting control pressure, the pavement heave gradually increases. It is recommended to adopt 0.8 times theoretical grouting pressure to ensure the thickness of the slurry sleeve meets the requirements and reduce the impact on the pavement; (3) setting concrete-filled steel tube curtain or anti friction slurry sleeve can reduce the impact of pipe jacking construction When the steel pipe curtain has been set up, there is no obvious back soil effect without the anti friction mud sleeve.