Calculation Of Surrounding Rock Pressure And Parameter Sensitivity Analysis Of Neighborhood Tunnel

The determination of surrounding rock pressure is the key to the design of tunnel lining support,especially for the neighborhood tunnel,how to quickly and accurately determine the size of surrounding rock pressure and failure mechanism is the top priority in tunnel design and construction.In this paper,theoretical analysis,numerical simulation and indoor model test are used to study the surrounding rock pressure of neighborhood tunnel.The main research results are as follows:(1)This paper summarizes the previous research status of surrounding rock pressure theory of neighborhood tunnel,and compares and analyzes the relationship and difference between the theories,so as to provide reference for the later research of surrounding rock pressure of neighborhood tunnel.(2)Based on the indoor model test,the progressive failure process and failure mechanism of surrounding rock of shallow buried tunnel with small spacing are revealed,and the failure mode of surrounding rock pressure calculation of shallow buried tunnel with small spacing is established.(3)Based on the upper bound theorem of limit analysis and related flow rules,the failure mode of multiple rigid blocks and its corresponding velocity field of shallow buried tunnels with small clear distance are constructed.The semi analytical solution of surrounding rock pressure of shallow buried tunnels with small clear distance is derived.The influence of various parameters(coefficient K,buried depth h,clear distance D,etc.)on surrounding rock pressure distribution under the failure mode is analyzed.(4)Using MATLAB software to optimize the objective function,the optimal upper bound solution of the surrounding rock pressure under the failure mode is obtained,and the optimal solution of the limit analysis in this paper is compared with the results calculated according to the standard method,which verifies the rationality and feasibility of the failure mode and theoretical calculation formula.(5)The relationship between the height of combined collapse arch and the aspect ratio of neighborhood tunnel under different surrounding rock grades is calculated by using the finite element numerical software,and the formula fitting is carried out.Then,based on the static equilibrium theory,the calculation formula of surrounding rock pressure of deep buried tunnel with small clear distance is derived,and the influence of various factors such as buried depth h,clear distance D and surrounding rock grade s on the surrounding rock pressure distribution of deep buried tunnel with small clear distance is discussed.