大断面组合式顶管机掘进排渣离散元仿真

顶管法已在地下工程中广泛应用,但对新型超大断面组合式顶管机掘进排渣过程中土体的运动和力学响应仍缺乏研究。本文建立了世界最大断面组合式顶管机的等尺寸模型,利用离散元法模拟顶管机的掘进排渣过程,研究排渣速度对土体运动行为和力学响应的影响。模拟结果表明,最佳的掘进-排渣速度比约为0.6 cm/rev,土仓流动性受上下两个半截面底部两侧刀盘的影响,滞排时土压随掘进累积增大,存在地表隆起倾向;超排时土压小于静止土压力,上覆土体随掘进由局部破坏发展为整体破坏。

DEM simulation of excavation and muck discharge of a combined pipe-jacking machine with a large section

The method of pipe jacking has been widely used in underground engineering. However, the research regarding the dynamics and mechanical responses of soil during the excavation process of the innovative combined pipe-jacking machine with a large section is still insufficient. A full-scale model of the combined pipe-jacking machine with the largest section in the world thus far is established in this study. The excavation and discharge process of the machine is modeled using the discrete element method (DEM), and the effects of discharge rates on the dynamics and responses of soil are analyzed. The results show that the optimal ratio of advance-discharge rate is approximately 0.6 cm/rev. The fluidity of soil is primarily influenced by the two cutterheads located at the bottom of both half sections. In the case of hypo-discharge, the soil pressure of the stratum cumulatively increases, and the ground surface is prone to rising. In contrast, in the case of hyper-discharge, the soil pressure is less than the static pressure, and a local failure of the covering stratum is formed, and then develops into a complete failure as the machine advances.