Research On The Seismic Calculation Method Of Railway Tunnel

Located between the Eurasia seismic zone and the circum-Pacific seismic belt, China is the largest continent shallow earthquake area around the world by the frequent earthquake activities. The seismic damage in China has the characteristics of wide distribution, high intensity and great harmfulness. Since the20th century, having experienced four seismic active periods, China is in the fifth period at the present. Despite of serious earthquake disaster by the frequent earthquake activities, China has become a country of the largest number, the largest scale and the fastest growing in tunnel construction. As the main railway lines are further extended to the western mountainous or hilly area, and the standards of high-speed railway are improved, the ratio of tunnel in trunk railway lines will be greatly increased. The tunnel project in railway engineering will become more and more important. And great quantities of tunnels being completed and under construction are located in high earthquake intensity area of China. As one of the main structure of the national lifeline, tunnel seismic calculation and design must be paid high attention. This dissertation is supported by Ministry of Railways key technology projects " Research on aseismic design standard and methods of railway tunnel", and Sichuan province scientific support plan " Key technology research of tunnel in high seismic intensity region ", and has carried out the research on the seismic calculation method of railway tunnel in combination with "Railway engineering aseismic design specification GB50111-2006" and the characteristics of the tunnel seismic design in China. The main work and research results are as follows.(1) Seismic damage examples and analysis of tunnelsOn the basis of tunnel damages at5.12Wenchuan earthquake and abundant seismic damage examples of tunnels at home and abroad, the earthquake damage models, the damage mechanisms and the influence factors of the tunnel are analyzed and summarized.(2) Tunnel seismic calculation method and their characteristicsThe characteristics and adaptabilities of earthquake coefficient method, seismic deformation method and dynamics time-history analysis of three commonly used seismic methods are concluded and comparatively analyzed as well as systematically studied. The corresponding evaluations and suggestions of tunnel seismic calculation methods are put forward.(3) Shaking table tests of tunnel earthquake responsesThe shaking table tests for different structure forms, different earthquake parameters, and different vibration directions, as well as different rock conditions, different buried depths, unsymmetrical loaded and symmetrical loaded tunnels are carried out. The earthquake response characteristics and rules of tunnel and surrounding rock are systematically studied. In addition, the shaking table tests for the isolation seism layer are completed to verify the shock absorption effect.(4) The brief and practical seismic calculation method of railway tunnelIn combination with the characteristics of the tunnel seismic design in China, earthquake coefficient method proposed by "Railway engineering aseismic design specification GB50111-2006" is reasonably modified by a large number of numerical calculations and validations of shaking table tests at typical working conditions. The brief and practical seismic calculation method of railway tunnel is proposed according to the different surrounding rock grade and different tunnel widths to adapt to the need of tunnel design and support the revision of the aseismic design specification of railway tunnel.To solve the railway tunnel construction problems in high earthquake intensity area of China, taking advantage of the data collection, theory analysis, numerical simulation, and shaking table test, the earthquake response characteristics and rules of tunnel and surrounding rock is ascertained. The earthquake coefficient method proposed by "Railway engineering aseismic design specification GB50111-2006" is reasonably modified in combination with the characteristics of the tunnel seismic design in China. The results will be useful to revise the aseismic design specification of railway engineering structures as well to provide support for actual project construction.