随着地铁车站在城市中的修建工期越来越紧张,一种车站修建新工艺“先隧后站”法应运而生且愈加成熟,其适配的开挖方法是“先隧后站”法中关键的一环。以重庆市4号线某暗挖地铁车站工程为依托,采用有限元软件FLAC3D对三种开挖方法(双侧壁导坑法、CD法和三台阶七步开挖法)进行数值模拟,研究得出了三种开挖方法下地层的沉降规律及车站支护结构、盾构临时管片衬砌与开挖之间的应力应变响应规律。结果表明:地层沉降随着埋深的增加而增大,其中双侧壁导坑法产生的沉降最小,三台阶七步法产生的沉降最大;三种开挖方法下锚杆及二次衬砌的应力分布规律几乎一致,其中双侧壁导坑法的锚杆轴力高出另外两种开挖法均约30%,而三台阶七步法的二次衬砌受力特征优于其他开挖法;对比盾构临时管片衬砌的应力应变分布规律,双侧壁导坑法明显优于CD法和三台阶七步法。

As the construction conditions of metro stations in cities become more and more complex, a new station construction technology “tunnel before station” method emerged and became more mature, and the appropriate excavation method is a key part of the “tunnel before station” method. Based on an underground subway station project of Line 4 in Chongqing City, this paper uses finite element software FLAC3D to conduct numerical simulation of three excavation methods (double-sidewall diversion method, CD method and three-step seven-step excavation method). The settlement law of the stratum under three excavation methods and the stress-strain response law between station supporting structure, shield temporary segment lining and excavation are studied. The results show that: The formation settlement increases with the increase of buried depth, in which the two-sidewall diversion method produces the smallest settlement, and the three-step seven-step method produces the largest settlement. Under the three excavation methods, the stress distribution of the bolt and the secondary lining is almost the same, in which the axial force of the double-wall driving method is about 30% higher than that of the other two excavation methods, while the stress characteristics of the secondary lining with the three-step and seven-step method are superior to the other excavation methods. Compared with the stress and strain distribution of shield temporary segment lining, the double-sidewall heading method is obviously superior to CD method and three-step seven-step method.