盾构隧道穿越断层破碎带开挖面稳定性研究

随着国内越江海隧道的快速发展，穿越断层破碎带盾构隧道开挖面稳定性的研究具有重要的理论价值和工程应用意义。文章考虑完整岩体与断层破碎带交界面的影响，改进既有楔形体 棱柱体模型，建立考虑地质交界面的极限平衡分析预测模型。基于极限平衡理论推导得到盾构隧道开挖面极限支护压力表达式，研究盾构隧道掘进趋近完整岩体与断层破碎带交界面过程中的极限支护力和破坏体倾角的变化规律。结果表明：当盾构隧道开挖面距离交界面较远时或已通过交界面后，隧道开挖面前方破坏岩土体范围都处于完整岩体或断层破碎带中，此时极限支护压力与常规的地层楔形体 棱柱体预测模型结果一致。当盾构隧道开挖面掘进至断层破碎带交界面距离小于临界破坏长度后，随着距交界面的不断减小隧道开挖面极限支护压力迅速增大，最大值约为完整岩体中极限支护压力的3.5倍，通过交界面后降低为断层破碎带中的极限支护力值。因此在该阶段应严格控制开挖面支护压力，避免发生涌水突泥事故。

The face stability of shield tunnel traversing the fault fracture zone

With the rapid development of the tunnels constructed under the rivers and seas in China, the research on face stability of shield tunnel in fault fracture zone with high hydraulic pressure has important theoretical value and engineering application significance. In this paper, considering the effect of interface between intact rock mass and fault fracture zone, the existing wedge-prism model is improved, and a new limit equilibrium prediction model considering geological interface is established. Based on the limit equilibrium theory, the expression of limit support pressure of shield tunnel surface is deduced, and the change laws of limit support pressure and failure inclination angle in the process of shield tunneling approaching the interface between intact rock mass and fault fracture zone are studied. The results show that when the shield tunnel face is far away from the interface face or has passed through the interface face, the failure range of the rock and soil mass in front of the tunnel excavation is consistent with that in the intact rock mass or fault fracture zone, and the result of the limit support pressure is consistent with the conventional existing wedge-prism model. When the shield tunnel is excavated to the distance of fault fracture zone interface is less than the critical failure length, as the distance decreases, the limit support pressure increases rapidly and the maximum is about 3.5 times than the value in intact rock mass. Therefore, the support pressure of tunnel face should be strictly controlled at this stage to avoid water gushing and mud sudden accident.