Optimization Of Support Parameters For The Main Structure Of Badaling Undergroud Staion Of Beijing-Zhangjiakou Interctiy Railway

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 support parameters. The related work and results are as follows:(1) Similar projects domestic and international and the main methods of support parameters optimization were briefly summarized, which provided instruction and reference for design and construction of Badaling underground station;(2) The current popular mountain tunnels'support types and their mechanical mechanism were comprehensively analyzed; the numerical simulation methods of different support types were summarized and appraised, which established the theoretical basis for optimization of support parameters;(3) This thesis evaluated Badaling underground station's geological conditions and the initial stress fields, and used finite difference software FLAC3D to simulate the whole process of mid-cavern excavation method for station;(4) This thesis detailedly analyzed related characteristics of surrounding rock which without any support structures in the process of mid-cavern excavation as well as finishing constructing, these characteristics included characteristics of stress field, characteristics of displacement field, plastic zone and so on, which provided a basis of deciding for the final specific of support parameters optimization of Badaling underground station;(5) In virtue of orthogonal testing method, choosing length of anchor bar, anchor spacing, row spacing 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.