Study On Construction Optimization And Estimation Of Stability For Shallow-buried Large Cross Section Rock Tunnel

Railway transportation as a great important communication infrastructure holds a high position in traffic system. Recently, with the rapid economic development in our country, the High Speed Rail construction has come to an age of speeding up, especially in mountain tunnels. For the property of large section tunnel is long span and complexity of construction method, it will cause too much soil disturbance and a complex stress. The key point for a tunneling method’s stability is to monitoring the disturbance and the stress.In the paper,based on the engineering of Xi’an-Chengdu high speed railway construction Deli tunnel, we start with acombination of the theoretical analysis, numerical simulation and field monitoring method.We made the conclusion of the best construction method and stabliaztion analysis of this large section tunnel.Firstly, we researched the theories in large section and heavy section tunnel related fields, check related information to master the large cross section tunnel under different working condition of mutual relationship between stress, deformation and settlement. According to the actual engineering data and field testing, we analyzed the stress of the large cross section tunnel under different working conditions, stability, settlement, etc. Secondly, under various operating conditions, we built2-D numerical model to simulate the excavation andanalized different working conditions of large cross section tunnel problems such as stress, deformation and settlement.Based on the 2-D numerical analysis results, we use 3-D numerical modles to simulate different conditons of the construction method.With the consideration of numerical analysis and the constructional economy and time cost, we optimized the construction method.Finally, the field monitoring were used to measure the simulated tunnel section.Using the compared data of the numerical simulation results and the measured values, we optimized the tunnel’s stability. The study on construction optimization and estimation of stability will provide some theoretical significance and constructional meanings.