Research on the Timing of Secondary Lining Support for Super-large Section Subway Tunnel

Abstract

For the super-large section subway station tunnel, the timing of the secondary lining support is very important in the construction of shallow tunnelling subway station with double-side-drift method. In order to study the reasonable support time of secondary lining of large section subway station, this paper takes Wulidian subway station belongs to Chongqing Rail Transit Line 9 as the background project, and adopts the numerical simulation method to analyze. In this paper, the influence law of secondary lining supporting time on deformation of surrounding rock, stress of shotcrete lining and secondary lining are investigated, during the construction process with optimization method. The analysis results show that during the construction of the background project, when the distance between the tunnelling face and the secondary lining increases by 4m, the vertical displacement of surrounding rock increases by about 0.15mm, the maximum principal stress of the shotcrete and secondary lining increases by about 0.39MPa and 0.5MPa respectively. When the distance between the excavated palm face of the lower core soil and the secondary lining is 16m, it is a reasonable time for the secondary lining support.