大跨地铁车站近接既有建筑非扰动施工数值模拟与工法比选

Numerical Simulation and Method Optimization of Non-Disturbance Construction for a Large-Span Metro Station Adjacent to Existing Buildings

摘要: 依托重庆轨道交通15号线金童路站暗挖工程，针对特大断面车站在既有建筑群正下方施工的扰动控制问题，基于MIDAS GTS NX建立了包含地层、既有建筑与隧道结构的三维数值模型，对盾构法与铣挖法两种非扰动开挖方案的全过程施工力学响应进行了模拟，系统对比了两种工法下围岩三向应力、关键部位主应力、塑性区分布以及拱顶、仰拱、边墙位移与既有建筑变形的差异。结果表明：两种工法下围岩应力均处于可控范围，盾构法引起的水平向与竖向围岩应力总体小于铣挖法，围岩最大竖向压应力盾构法为1.92 MPa，铣挖法为2.16 MPa；盾构法下拱顶沉降3.25 mm、仰拱隆起5.90 mm，均小于铣挖法的5.75 mm与7.97 mm；盾构法下既有建筑最大位移1.652 mm，约为铣挖法3.270 mm的一半，两种工法下建筑变形均满足控制要求。综合施工安全、工效与环境影响，盾构法为该工程最优的非扰动施工方案，研究结果可为类似近接既有建筑的大断面地下工程工法选择与施工控制提供参考。

Abstract: Relying on the mined Jintongli Road Station of Chongqing Rail Transit Line 15, a three-dimensional numerical model including strata, existing buildings and tunnel structures was established with MIDAS GTS NX to address the disturbance control problem of a super-large cross-section station constructed directly beneath existing buildings. The whole-process mechanical responses of shield tunneling and milling excavation were simulated, and the differences in surrounding rock stresses, principal stresses at key positions, plastic zones, displacements of the crown, invert and sidewall, and deformation of existing buildings were compared. The results show that the stresses of the surrounding rock are controllable under both methods. The horizontal and vertical surrounding rock stresses induced by the shield tunneling method are generally lower than those induced by the milling excavation. The maximum vertical compressive stress in the surrounding rock is 1.92 MPa for the shield method and 2.16 MPa for the milling excavation. The crown settlement under the shield method is 3.25 mm and the invert heave is 5.90 mm, both smaller than the 5.75 mm and 7.97 mm for the milling excavation, respectively. The maximum displacement of the existing building under the shield method is 1.652 mm, approximately half of the 3.270 mm under the milling excavation. The building deformation meets the control requirements under both methods. Considering construction safety, efficiency, and environmental impact, the shield tunneling method is the optimal non-disturbing construction scheme for this project. The research results can provide a reference for the selection of construction methods and construction control of similar large-section underground projects adjacent to existing buildings.