| Summary: | 碩士 === 國立金門大學 === 土木與工程管理學系碩士班 === 106 === The objective of this research is to develop the fragility curves of the defense shelter tunnels subjected to seismic responses. Qiong-Lin Battle Tunnel will select as a case study, because this tunnel has numerous tourists to pave a visit here. The emphasis of this study will focus on the safety of this tunnel.
Prior to 410 years ago, in 1604, a 7.5 magnitude earthquake struck Kinmen Island. Tremendous loss of lives and damage of structures on this island had been recorded in the history.
Because of the Civil War, numerous defense shelter tunnels had been constructed on this island. Most of them have been demolished or abandoned, but this unique feature of this underground structure attracts numerous tourists to visit and to experience walking inside of the tunnel. The safety of these tunnels becomes the main concerns for tourists. However, very few research conducting the safety evaluation of the defense shelter tunnel on this island. This is a motivation to do this research to provide a safety evaluation. Furthermore, if it were not adequate in the structure strength, the retrofit of this tunnel will be proposed.
This research is presented in seven chapters. In the first chapter, the motivation, objective, methodology of the research, and outline of this study are described.
Chapter 2 deals with the literature review. The topic describes related studies on underground structures subjected to earthquakes, soil-structure interaction of the tunnels, and quiet elements of the soil medium.
Chapter 3 covers the description of Qiong-Lin Battle Tunnel in Kinmen. The dimension of design sheets are verified with the field measurement. The locations and severity of the tunnels were identified and recorded.
Chapter 4 provides the tunnels subjected to the external forces. The forces include: one is the heavy truck loads on the ground levels during infrastructure construction, and the other is the seismic loadings. The shear velocities in close proximity to the sites were calculated on the basis of the bored holes. The contour lines of the identical shear velocities are illustrated accordingly.
In addition, these velocities are the basis of the site classification. After the site is determined, the selection of input ground accelerations can be made with the compatible design spectra.
The soil medium is modeled with the near-field nonlinear springs on the basis of the ALA design code. In addition, the far-field soil medium is modeled with a linear elastic shell element. The quiet elements are also adopted to avoid the reflection of the shear waves.
The safety evaluation of the basement excavations closed to tunnels is also performed. The capacity of the tunnels is achieved with the nonlinear pushover analysis.
In addition, the modal analyses are performed in Chapter 5. Several results are achieved with the numerous nonlinear analyses. These can be included two parts: one for the tunnel sections with oval deformations, and the other for a three dimension analysis with a nonlinear spring boundary.
Chapter 6 is devoted to the development of the fragility curves. The maximum likelihood theory is utilized to achieve the fragility curves. The damage criteria of the underground structures are mainly dominated by the surrounding soil relative displacements. The drift failure of the tunnels serves as a damage index to classify the probability of the different damage states in terms of the PGA.
The conclusions and final remarks are addressed in Chapter 7.
The fragility curves developed in this research provide the safety evaluation of the defense shelter tunnels in Kinmen.
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