Structural Optimization Of Badaling Underground Station With Three Span Tunnels Of Beijing-Zhangjiakou Intercity Railway

ABSTRACT:Badaling underground station is the focus control project of the proposed new Beijing-Zhangjiakou intercity railway. Railway station will be built in the mountain, for the first time it is constructed in China, being rare in the world. Because of deep setting depth, large excavating area, as well as the complex structural type, similar projects for reference is lacking in the preliminary design stage, as a result, there are great ambiguity and uncertainty on the selection of construction methods and support parameters.Basing on the main structure of Badaling underground station, this thesis will mainly study on how to optimize the station's construction methods. The related work and results are as follows:(1) Similar projects domestic and international and the main methods of construction were briefly summarized, which provided instruction and reference for design and construction of Badaling underground station;(2) The current popular mountain tunnels'construction methods and their mechanical mechanism were comprehensively analyzed, the numerical simulation methods of different construction methods were summarized and appraised, which established the theoretical basis for optimization of construction methods;(3) This thesis detailedly analyzed related characteristics of surrounding rock in the process of mid-cavern excavation as well as finishing constructing, these characteristics included characteristics of stress field,which provided a basis of deciding for the final specific of construction methods optimization of Badaling underground station;(4) In virtue of orthogonal testing method, choosing way of construction order, length of anchor bar, and thickness of spray layer as variables, the stability of surrounding rock was roundly assessed by roof-to-floor relative displacement, two sides relative displacement, surface subsidence and plastic zone volume and so on, finally the optimum scheme was obtained. This will provide some scientific theory evidence and have significant meanings for follow-up design and construction of Badaling underground station.