| When the long tunnel passes through the fault broken zone, it is easy to appear the deformation, collapse and other disaster problems, which seriously affect the safety and progress of construction , and endanger the safety of personnel. At present, the construction technique of safe and rapid crossing fault fracture zone is not mature. Therefore, it is of great practical significance to study systematically the rapid and safe construction of the tunnel through the fault fracture zone.Based on the engineering background of the Mountain Railway Tunnel, this paper first sums up the stability analysis of the surrounding rock in the fractured zone of the tunnel through fault the research actuality of the theory and method of tunnel support, secondly, the paper studies the tunnel structure deformation, stress and safety of tunnel crossing fault zone, and then optimizes the construction parameters of the project, and analyzes the data of the tunnel crossing fault zone. The main contents and achievements of this paper are as follows:(1) Analysis on the stability of tunnel with different dip angle faultsCombined with the geological structure of Mountain Project , through three-dimensional numerical simulation, the paper firstly analyzes and sums up the changing law of tunnel structure deformation and stress when crossing different inclination angles (such as 75°, 90°, 105° ) fault fracture zone. Then it discusses the feasibility of tunnel excavation and not doing initial support,analyzes and sums up the necessity of advance reinforcement, and finally makes a numerical analysis of the advance strengthening action of the tunnel crossing fault zone, and evaluates the safety of the tunnel structure , and verifies the effectiveness of the advanced reinforcement.(2) Optimization analysis of construction parameters of tunnel crossing fault ZoneCombined with the construction method of mountain railway tunnel concrete and supporting design, through three-dimensional numerical simulation of tunnel excavation footage and optimize the thickness of reinforced zone, from the tunnel structure deformation, stress, safety and other aspects of the comparative analysis,summarizes the influence of different construction parameters of the tunnel , and ultimately determine the reasonable construction the parameters, to ensure the safe and rapid construction of tunnel engineering.(3) Analysis of site construction monitoring resultsThrough the study of the field monitoring of typical section of tunnel, first analyzed the up and down the steps excavation supporting contribution to the tunnel deformation, the arch in the process of settling accounts for about 80%～85% of total settlement, and comparative analysis of the first line and second line respectively the role of structure deformation and stress of the tunnel, and their respective functions and contributions, lining as the main load-bearing structure of construction period at the beginning of the second lining as a safety reserve, The load sharing ratio of the initial support is 69.3%, and the load sharing ratio of the two lining is 30.7%, finally the field monitoring data and carries out a comparative analysis on the results of numerical calculation, to verify the numerical simulation method and the rationality of analysis method, in order to better guide the design and construction of similar projects.In a word, this paper analyzes the influence law of fault crushing zone on tunnel excavation from many aspects, verifies the rationality of "pipe advance and short footage" in tunnel excavation of weak surrounding rock, complements and perfects the research ideas of tunnel crossing fault Zone,and provides reference for this project and similar projects. |
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