Analysis Of Comprehensive Influence Of Large Span Subway Station Construction With PBA Method On Neighboring Existing Subway Station

At present, there are many of methods for construction of subway stations or other underground projects. Nevertheless, as one of construction method, PBA method has lots of advantages, such as high utilization rate of transverse section, strong applicability, less duration for construction, relative low costs, and so on. It is now widely used in the field of underground projects. In this paper, the large-scale Puhuangyu Station intersected with the existing line 5 in the new Beijing Subway line 14 is used as the background. A three-dimension model are established, it includes the two-story part and the three-story part (contains the station of existing subway line 5) of the station. And then, this paper gives a preliminary study about the problems relate to this project by the way of numerical calculation with the large general-purpose FEM software ANSYS.The main study contents:①The influence of ground surface subsidence caused by PBA construction method;②The influence of structure mechanical behavior about existing Metro line 5 station during the construction of new Metro line 14 station with PBA method;③The influence of structure mechanical behavior and subsidence of trajectory surface about existing Metro line 5 station while the mainline tunnel built by mining method pass through beneath the subway line 5 station almost meet each other;④The impact of punching hole in bent wall of existing subway line 5 station by transfer channels;⑤Optimizing control of subsidence on trajectory surface of the existing subway line 5 station.Based upon the study content, some main related results got in this paper:①Ground surface subsidence of two-story part of new subway line 14 station is slightly less than that of three-story part of the same one during the construction of new subway line 14 with PBA method. The ground surface subsidences of them are 42.10mm and 47.76mm;②Because far from the existing subway line 5 station, the influence of the construction of new subway line 14 station are negligible. The main affects for the existing subway line 5 station are the excavation of mainline tunnel and punching hole in bent wall in existing subway line 5 station by transfer channels. Stresses of existing subway line 5 station have increased to some extent during the mainline tunnel excavation progress. Stress intensity distributed around edges of the holes are relative stronger than other parts. Especially for the corners of holes, its stresses intensity are far stronger than any other part of the existing subway line 5 station brace system;③The excavation of mainline tunnel have stronger influence to the trajectory surface subsidence of existing line 5 station relative to other progress;④After the formation of the main structure, stresses of new subway line 14 station changes small, and some local parts have greater stress concentration;⑤It is can effectively control and reduce the trajectory surface subsidence of the existing subway line 5 station by using different kinds of expanded-grouting sections.Although this paper gave some segmental results, and it have some reference values to a certain extent for other similar projects, but this is only a preliminary study, there are still more problems for a further research.