Study On Factors Of Influencing Rock Stability Of Advance Reinforced Tunnel With Large Cross-Section

In the engineering background of Liuyang River tunnels on Passenger Dedicated Railway from Wuhan to Guangzhou, research was carried out synthetically and systematically on factors influencing rock stability of shallow advance strengthening tunnel with large cross-section, by use of numerical simulation, model tests, field trials and other research tools.It was of great practical significance to research and develop on the pre-reinforcement method of shallow tunnel with large cross-section, to fill our country's gaps of the pre-reinforcement technology for shallow large-section tunnel and provide a theoretical guide for its construction. In this paper, the following research work was completed. 1. Comprehensive study on factors was conducted,including the contents and level of factors influencing rock stability of advance reinforced tunnel with large cross-section,and the parameter sensitivity.2.Through the study of factors sequence, the descending factors sequence whice influnced working face deformation was obtained,which was tunnel face pre-reinforcement, rock-level, construction methods, excavation footage and shelf-type support. The one which influnced vault deformation were rock-level, construction method, tunnel face pre-reinforcement, shelf-type support,and excavation footage.3.Parameter sensitivity study showed that grouting effect of working face was the only sensitive parameter of pre-reinforcement of GFRP anchor,in meeting the critical lap length. Shelf-type support parameters provide little effect on the surrounding rock deformation.4. Tunnel face stability was divided into three levels of A,B and C in NITM. In this paper,the railway tunnel surrounding rock classification and section size were taken as the main factors to propose a new classification method and classification number of the tunnel face stabilization.5. Based on the study of factors sequence and classification of the tunnel face stabilization, construction parameter series of advance reinforced tunnel with large cross-section were obtained to provide the reference basis for the construction of shallow tunnel with large cross-section for all grades of surrounding rock. 6.According to the parameter series of advance reinforeced tunnel with large cross-section, the best constuction parameters were obtained,which would be verified by model tests and field trials in the construction of Liuyang River tunnels on Passenger Dedicated Railway from Wuhan to Guangzhou.This research basically formed with pre-reinforcement technique which had the characteristics of China's large-section tunnel.The results had been successfully applied in Liuyang River tunnels on Passenger Dedicated Railway from Wuhan to Guangzhou.