关键词:

地铁车站, 改扩建, 深基坑, 明挖, 盖挖, 钢管混凝土柱

Abstract: During the rehabilitation of an existing metro station, a series of problems occurred, such as the water and soil pressure imbalance between the newlyadded semirange station and the existing foundation pit, large width of the foundation pit extended at both ends, and complex traffic diversion and reconstruction of transfer node. Accordingly, a set of relatively perfect rehabilitation scheme is formed through detailed comparison and analysis of foundation pits in each section based on numerical analysis results considering various action combinations and structural type transformation in construction process and permanent use stage. The main conclusions are drawn as follows: (1) The existing semirange of the foundation pit has been excavated to the bottom, thus the new half should be constructed by the cutandcover topdown method. (2) The extended foundation pit at both ends should be constructed by the combination of open cut and cutandcover methods, and the anchor cable support that can be recycled should be adopted. (3) The foundation pit at the transfer node should be constructed by the cutandcover topdown method. (4) The concretefilled steeltubular column combined with temporary column and permanent column should be adopted for the vertical support components of the cutandcover section, and the middle pile foundation (also used as uplift pile) shall be set under the column. In addition, the timehistory analysis method is used to verify that the main structure of the station can meet the requirements of seismic performance Ⅱ under levelE3 earthquake effect.

Key words: metro station, reconstruction and expansion, deep foundation pit, open-cut, cut-and-cover method, concrete-filled steel-tubular column