Structural Optimization Of Badaling Underground Station With Cross-section Of Three Single Tunnels Of Beijing-Zhangjiakou Intercity Railway

Badaling Underground Station of Beijing-Zhangjiakou Intercity Railway will be built in Badaling mountain where is National Nature Reserve. It's the first intercity railway example which is constructed in the mountain, also is rare in the world. Badaling underground station is the focus control project of the proposed new Beijing-Zhangjiakou intercity railway because of deep setting depth, large excavating area, as well as the complex structural type. As far as now, there is few similar preliminary projects for reference. As a result, Engineering analogy method can't provide effective function.So it is necessary to do some research on the proposed structure program.Based on the main structure of Badaling underground station, this thesis will mainly do research on the optimization of the station's support parameters. The related work and results are as follows:(1) Such projects' features and difficulties, and overview of similar projects and reserch at home and abroad were briefly summarized. Which provided instruction and reference for design and construction for Badaling underground station;(2) The basic theory of mechanics of the tunnel and underground caverns, and the mechanical properties of the various parts of Tunnels and underground rock in the construction were comprehensively analyzed. Various factors affect the stability of surrounding rock were studied. And anchoring mechanism of anchor supporting in the"New Austrian Tunneling Method" was described in detail. It Provides a theoretical basis for excavation and surpporting of badaling Underground Station of Beijing-Zhangjiakou Intercity Railway.(3) The current contents and methods of structural optimization for underground structures were studied,which provide guidance for Badaling underground station(4) Badaling underground station's geological conditions were evaluated in this thesis.The finite difference procedure FLAC3D was used to simulate the whole process of three-step excavation method for the independent three tunnels' structural station;Also This thesis detailedly analyzed stability of surrounding rock and support structure under different excavations, and selected a suitable construction plan.This provided a basis of deciding for the final specific of support parameters optimization of Badaling underground station;(5) The orthogonal testing method was used to choose the more important factors from length of anchor bar, anchor spacing, row spacing and thickness of spray layer,by the evaluation index roof-to-floor relative displacement and two sides relative displacement. Then utilized the Quadratic Regression Test to do further research on length of anchor and thickness of spray layer. And finally determined the relationship between the thickness of sprayed concrete floor, bolt length and the roof-to-floor relative displacement, and made out the optimum scheme. This will provide some scientific theory evidence and guidence for follow-up design and construction of Badaling underground station.