Study on surface settlement and structural deformation for large span subway station using a new pre-supporting system

A new construction pre-supporting system, Steel Tube Slab system (STS), is proposed for large underground space excavation with shallow depth. The adjacent steel pipes in STS method are connected by a couple of flanges, bolt and concrete in order to improve the flexural capacity and lateral stiffness of the whole structure. STS method is firstly adopted to construct the ultra-shallow buried and large span subway station in China. Ground settlement and structural deformation are monitored during the construction. A numerical model is established for the subway station, the reliability of the numerical model is verified by comparing the numerical results with monitored data. The influence of large span underground excavation on surrounding soil and existing buildings in soft soils are investigated. Results prove that STS method can effectively control and reduce the ground settlement during construction. This study can provide a strong guidance for application of STS method in soft soils....针对浅埋大跨度地下空间开挖工程，本研究提出一种新型施工预支护体系——钢管板体系（Steel Tube Slab system，STS）。该体系中相邻钢管通过成对法兰、螺栓及混凝土进行连接，以提升整体结构的抗弯承载力与侧向刚度。STS工法已在国内首次应用于超浅埋大跨度地铁站的施工建设。施工过程中，对地表沉降与结构变形开展了现场监测；针对该地铁站建立数值分析模型，并通过将数值模拟结果与监测数据对比，验证了模型的可靠性。研究了软土地层中大跨度地下开挖对周边土体及既有建（构）筑物的影响。结果表明，STS工法可在施工过程中有效控制并降低地表沉降。本研究可为STS体系在软土地层中的推广应用提供有力指导……