盾构重叠隧道施工力学行为分析

我国地铁建设的快速发展，就涉及地铁建设中上下重叠隧道的相关问题进行研究。利用三维有限元方法并结合广州某重叠盾构施工的地铁工程实例分析了下洞（左线）隧道受上洞（右线）开挖产生的影响范围、上洞盾构在不同推进力下对下洞位移、应力和应变产生的影响和下洞局部范围在有临时支护条件下随上洞开挖产生位移和内力变化。分析表明：下洞隧道结构受上洞盾构施工的影响表示形式为上洞盾构前方的下洞结构存在向下桡曲，而在后方则向上隆起，直至趋于一个定值，其中下洞盾构机的盾尾需在上洞盾构机盾头前方的50 m；上洞隧道在推进过程中，推进力是控制下洞结构变形的主要因素。此时，应严格控制上洞盾构隧道施工时盾构机推进力大小并仔细对下洞结构变形进行监测；对下洞隧道施作临时支撑可以有效减小位移和结构的受力特性；分析计算得出的结论对于盾构重叠隧道设计和施工有一定指导意义。

Analysis of Construction Mechanical Behavior for Overlapping Tunnel Shield

In view of the rapid development of subway construction , issues related with the construction of vertically stacked subway tunnels are studied .Based on the example of Guangzhou metro overlap shield tunneling construction , through the dimensional finite element method , the influence of the upper hole （ right lane ） on the lower hole（left lane） construction, including the impact range of upper hole excavation on the lower hole , the influence of the upper hole shield under different propulsion on the displacement , stress and strain of the lower hole , and local displacement and force changes of the lower hole with temporary support conditions under the im -pact of the upper hole excavation .Analyses show the lower hole structure goes downward at the front end of the upper hole shield , and goes upward at the rear end , until it tends to be a constant value .In the case of the ex-ample of this article , the lower hole shield machine tail need to be 50 m in front of the upper hole shield machine head;In the advancing the process of the upper hole , propulsion force is the main factor to control lower hole structure deformation .thus the upper hole TBM propulsion should be strictly controlled during tunneling and low -er hole structure deformation carefully monitored;temporary support structure for the lower hole tunnel can effec-tively reduce the displacement and stress .The conclusion of this article may provide some guidance for overlap shield tunnel design and construction .