Seismic Analysis of Underground Twin-tunnels

• Main Authors: Pei-Lin You, 游佩琳
• Other Authors: 楊永斌
• Format: Others
• Language: zh-TW
• Published: 2014
• Online Access: http://ndltd.ncl.edu.tw/handle/21418313416085210663

碩士 === 國立臺灣大學 === 土木工程學研究所 === 102 === With the increase of urban population, the traffic congestion problem has become more and more serious in metropolitan areas. For its instant, convenient, high frequency service and high capacity characteristics, mass rapid transit (MRT) system has become one of the major transportation tools in metropolitan areas. Owing to the limited and precious ground areas available, most MRT routes have been built as underground tunnels, which can not only save the ground space, but reduce the noise interference. Taiwan is an island located on the circum-Pacific seismic belt where a large number of earthquakes occur each year. When a major earthquake takes place, it may cause the moving MRT trains to derail, or make underground tunnels collapse, thereby resulting in tremendous casualties because of the high capacity characteristics of the system. In view of the above, the purpose of the thesis is to investigate the impact of earthquakes on the underground tunnels by using numerical simulation methods. The study simulated the soil-structure interaction system by using the 2D coupled finite/infinite element approach method proposed by Yang et al. (1996). In order to deal with the wave scattering problem and to analyze the soil-tunnel interaction behaviors subjected to earthquakes, the study also adopted Zhao and Valliappan’s (1993) technique for simulation of the earthquake, and compared the numerical results obtained with the previous studies. Besides, this study investigates the seismic responses of single tunnel and twin-tunnels by utilizing the seismic data recorded during the 921 Chi-Chi Earthquake. Furthermore, parametric studies were conducted to examine the effects of various geometric and material parameters, such as the depth of the tunnels or the space between twin-tunnels, on the tunnel response. The study results show that the soil shear wave velocity and the depth of the tunnels are important parameters with respect to the seismic responses of the tunnels; however, the depth of the tunnels and the relative position of twin-tunnels have less influence on the seismic responses of the ground. In addition, the interaction between the twin-tunnels can result in the change of the principal stresses distribution on the adjacent sides of the two tunnels.