在既有建筑下修建浅埋暗挖岩石车站的关键技术

在既有建筑下方修建浅埋暗挖岩石车站的工程难度极大，如何保证上部既有建筑的安全和正常使用以及新建工程的安全是设计、施工的难点。以重庆北站(南广场)为例，提出在既有建筑下方修建浅埋暗挖岩石车站的若干关键技术，并通过数值模拟、现场监测进行验证，可为类似工程提供参考。研究结果表明：对大跨度、扁平的单层暗挖车站，在浅埋岩层中近距离下穿建筑物时采用中洞法是合理可行的，通过采取适当的工程措施能避免上部基础产生冲切破坏，有效保护建筑物，中洞结构施工是变形控制的关键工序；对浅埋岩层中的多层多跨地下结构，提出拱柱法的施工方法，解决传统PBA (框—梁—拱)工法应用于岩层时存在的开挖工序多、施工效率低等问题，能有效控制地层及上部建筑变形，其中地下一层结构施工是变形控制的关键工序。该方法对强风化及更好岩层中变形控制严格的地下车站具有重要应用价值。

Key Technologies for the Construction of Shallow-Buried Rock Metro Stations under Existing Buildings

The construction of shallow-buried underground rock stations under existing buildings is a particularly challenging engineering process. Ensuring the safety and normal use of existing superstructures is a key point in the design and construction. Taking Chongqing North Metro Station as an example, this paper proposes the construction technologies of shallow-buried rock stations under existing buildings, whose efficiency is verified by a numerical simulation and field monitoring. The technologies provide reference for similar projects. The research conclusions are as follows: For long-span and flat single-layer underground stations, the use of the mid-tunnel construction method is reasonable and practical when the station is nearly under a building in a shallow-buried rock stratum. The punching failure of the upper foundation can be avoided, and buildings can be effectively protected by taking rational engineering measures, and the construction of a structure in the mid-tunnel is the key process of deformation control. For multi-story and multi-span underground structures in shallow rock strata, the arch-column construction method is proposed. The method alleviates the challenges of having numerous excavation procedures and the low efficiency when the traditional pile-beam-arch construction method is applied to the rock strata. Moreover, this method can effectively control the deformation of superstructures, in which the construction of an underground one-store structure is the key process. This method can be applied to underground stations with strict deformation control in strong weathering and better strata.