NUMERICAL ANALYSIS OF THE MECHANICAL EFFECT OF REACTION FORCE OF RECTANGULAR PIPE JACKING IN LARGE SECTION

With the background of the comprehensive pipe corridor project in Changhe West Road, Tongzhou District, Beijing, the simulation model of the back wall system of the pipe jacking initiation shaft was established by ABAQUS software in order to study the effect of jacking reaction force on the back wall system of rectangular pipe corridor with large section. This report analyses force and deformation of the back wall system and the surrounding soil layer in different jacking stages, by combining the jacking force monitoring data during the whole process of pipe corridor jacking. The numerical simulation results show five main results. The horizontal displacement of the back-back soil in the loading area increases and then decreases with the increase of depth under the action of the reaction force, while the horizontal displacement of the front wall soil gradually decreases with the increase of depth. The horizontal displacement of the surface soil around the wall gradually decreases with the increase of distance from the well perimeter; and the soil displacement decreases significantly within the reinforcement area, while the vertical displacement does not change significantly. The overall soil pressure is smaller than the passive soil pressure when back soil pressure in the loading area increases; and the overall soil pressure is smaller than the static soil pressure when the overall soil pressure at the front wall decreases. The soil reaction force and displacement at the loading centre show a linear trend with the increase of the top force. The concrete support at different locations of the starting well is significantly affected by the reaction force.