Subway Tunnel Across The Existing Bridge And Ground Fissures With The Construction Site Monitoring And Numerical Simulation

As a kind of geological disaster distributed in many parts of China, ground fissure has given great impact and economic losses to people's life. Xi'an is one of the areas which suffered most from the ground fissure disaster. With the development of the city, the influence of the ground fissure becomes more obvious, such as No.2 Xi'an subway crossing many ground fissures. In order to ensure the safety of excavation and operation of subway tunnels in the zone of ground fissures, and also to provide reference for the similar constructions in the future, by taking NO.2 xi'an subway crossing f6 ground fissures segment and through the means of field monitoring and numerical simulation, this paper has studied the laws of Chang'an Interchange settlement and ground movement in the process of tunnel construction. The contents are mainly as follows:1. Introduced ground fissures distribution in China, summarized the reasons and the development of ground fissure hazards in our country and described the distribution and general geology of more than ten bands ground fissures in Xi'an area.2. Through the means of field monitoring, this paper has studied the laws of Chang'an Interchange settlement and ground movement in the process of tunnel construction. f6 Ground Fissure has significantly influenced on the settlement of Chang'an Interchange. Compared with some specifications, it is considered that Chang'an Interchange is safe in construction process and meets the operating requirements.3. Based on monitoring analysis, and according to the field practical situation, three-dimensional simulation has been conducted by ABAQUS finite element program on the spot. Compared the measured data and simulation value, and through simulation value, the author has analysized the law of layer level displacement and stress distribution of tunnel lining and surrounding rocks.4. Through collection of designing about several ground fissures in Xi'an area and No.2 Xi'an subway, this paper has established two-dimensional model with different horizontal distance from the tunnel center to the ground fissures. According to the simulation results and based on standard of maximum allowable ground settlement resulted from excavation of the subway in Beijing and Shenzhen, the author has reached the results that the suggested minimal fortification distance in Xi'an area subway tunnel near the ground fissures.