滨海地区盾构隧道近接下穿既有车站施工力学特性研究

Research on Construction Mechanics Characteristics of Shield Tunneling near Existing Stations in Coastal Areas

摘要:

依托福州地铁滨海快线福东区间下穿既有地铁4号线工程，采用FLAC3D平台开展精细化数值模拟。基于盾构掘进过程中的土体-盾构相互作用（如掌子面压力、注浆压力、盾壳摩擦力、刀盘扭矩）以及同步注浆的硬化与压力消散的影响，探讨邻近车站条件下盾构隧道近接下穿的施工力学特性。数值模拟与实测结果表明：既有地铁4号线车站及区间隧道在盾构掘进过程中以沉降为主，变形特征由单线下穿的“V型”演化为双线下穿后的“W型”。既有地连墙对土体变形主要表现为阻隔和牵制，有效减小既有4号线车站及区间隧道的变形。研究结论可为相似条件下盾构近接下穿工程的设计与施工提供理论支撑与实践参考。

Abstract:

Relying on the project of the Fudong section passing under the existing Metro Line 4 in Fuzhou Metro Binhai Express Line, the refined numerical simulation is carried out based on the FLAC3D platform. Based on the consideration of the soil-shield interaction during the shield tunneling process (such as face pressure, grouting pressure, shield shell friction force, cutter head torque), and the hardening and pressure dissipation of synchronous grouting, the construction mechanics characteristics of the near-passing of shield tunnels under the adjacent stations are discussed. The numerical simulation and measured results show that the existing stations and interval tunnel of Metro Line 4 are dominated by settlement during the shield tunneling, and the deformation features evolve from a “V shape” with a single-line underpassing to a “W shape” after a double-line underpassing. The existing diaphragm wall mainly manifests as barriers and restraints on soil deformation, which can effectively reduce the deformation of the existing stations and interval tunnel of Metro Line 4. The research conclusions can provide theoretical support and practical reference for the design and construction of shield near-tunneling projects under similar conditions.