冻结暗挖法在地铁车站附属结构中的应用

Application of Freeze Excavation Method in Attached Structure of Subway Station

某地铁车站边上有三组地下高压电缆管廊横跨出入口和风道,下穿管廊段结构采用冻结暗挖法施工。地铁车站附属结构为矩形断面,跨度大,覆土小,与管廊斜交,且所处地层条件差,周边环境复杂。分析了工程技术难点,研究了冻结设计方案及关键施工措施。沿通道结构四周布置水平冻结管,形成强度高、封闭性好的冻结帷幕,兼做挡土和隔水作用,然后对开挖掌子面进行全断面注浆加固,之后采用CRD(交叉中隔壁)工法进行暗挖施工,结构施工完成后采用双液浆进行注浆。最后,采用有限元软件对冻结壁受力及位移进行了计算模拟,验证了设计方案的可行性。

There are three groups of high-pressure pipe galleries across the attached structure on the entrance and air duct of a metro station in Nanjing. Horizontal ground freezing and undermining method is adopted for the pipe galleries. The attached structure is a rectangular section with large span, shallow soil cover and oblique crossing the pipe galleries, the construction condition is very bad. After analyzing the technical difficulties in the project and the key construction measures in freezing scheme design, the horizontal freezing pipes are arranged around the attached structure to form a freezing curtain which will retain soils and isolate water; then the whole excavating face is strengthened by grouting, followed by excavation with CRD （central cross diagram） method and the soil is grouted with double-liquid cement after the construction. Finally, the stress and displacement of the frozen soil are computationally simulated with finite element method, the feasibility of the design is validated.