Security Risk Management Of Large-span Shallow Tunnel Beneath Highway In Beijing To Shanghai High-speed Railway

Tunnels of Beijing to Shanghai high speed railway have large-span, shallow, and beneath a variety and special of adverse geological conditions. Especially for the risk management and control during the process of Beijing to Shanghai high speed railway beneath Beijing to Fuzhou Expressway.This paper is focusing on the complex condition and risk control of Beijing to Shanghai high speed railway tunnel beneath the highway. At first, similar material, which was suitable for simulating the rock of beneath section, was researched and prepared. Non-linear regression analysis was used for determining changes on elastic modulus and other functions and trends of relevant indicators of similar material. Quadratic combination universal rotary design of response surface analysis was used for exploring the physical and mechanical indices of similar material such as cohesion and internal friction angle. After that, the best ratio of model test about IV level rock was determined. At second, combining scale model test and numerical simulation the two ways, scale model test of beneath section was designed. Model test with the ratio of 1:30 is prepared to identify pipe roof, advanced small pipe and other advance protection measures which are to be adopted during the beneath process. A variety of measures to pre-support were compared for the effects on controlling surface subsidence and rock pressure, and the final pre-support was fixed. Combining with the actual situation of beneath section, numerical simulation method was used to compare 6 construction methods such as two-step method. Through the calculation of surface subsidence, contact stress between surrounding rock and early support, early support and second lining. The best method for controlling risk of beneath section was fixed. Finally, through the way of monitoring, layouting monitoring instruments in beneath section, during excavation was monitoring, change processes of internal forces were analyzed and at the same time, the result of scale model test and numerical simulation was verified.