The Mechanism Research Of The Subway Tunnel Surrounding Rock Pressure

Recently, vigorous development of metro project brings both opportunities and challenges for the development of the tunnel and underground engineering. Compared with the more mature theoretical studies of designing and calculation method of the railway tunnel, the design of metro tunnel is still in the preliminary stage of development, and a lot of design theory research still refer to the railway tunnel standard. Especially, the calculation of surrounding rock pressure of the subway tunnel has no clear designing method. Therefore, based on the present situation of the surrounding rock pressure research, this article study on the formation law of the surrounding rock pressure arch, and put forward the calculation method of corresponding pressure arch boundary. The main research contents and results are as follows:(1)The theoretical analysis of the pressure of surrounding rock arch. On the basis of Rock and Soil Mechanics theory, combined with the existing research results, the formation law of the pressure of surrounding rock arch are putted forward, and the theoretical analysis of the shape of the surrounding rock pressure arch is a ring-shaped body, and this paper proposes the sphere of influence of the surrounding rock pressure arch which is the boundaries of the inside and outside.(2)The numerical simulation analysis for the surrounding rock arch are achieved by contrast the main stress vector of before and after the excavation of surrounding rock. It can be clearly found that after the tunnel excavation, the direction of principal stress vector of the surrounding country rock deflected, and it formed the formation of a closed circulation,which is the pressure arch intuitive embodied in the numerical simulation,confirming the pressure arch shape is a ring. Subsequent analysis of the influencing factors of surrounding rock pressure arch relationship has been the pressure arch and the impact of various factors. Influenced by many factors, combined with the means of sensitivity analysis, the main factors affect the pressure arch outer boundary, and thus deduce the calculation method of outer boundary of the pressure of surrounding rock arch.(3)Through the summary analysis of the surrounding rock pressure arch performance characteristics, and focused on the research of the tunnel span, buried depth, rock mechanics parameters and surrounding rock stress release rate of pressure arch effect, it obtained the pressure arch outer boundary calculation formula. On this basis, according to the existing surrounding rock pressure design calculation of the theoretical foundation, this paper puts forward the calculating method of the theory of arch based on pressure of surrounding rock. Finally, set the Beijing subway line10for example, the proposed design method is validated.