| Summary: | 碩士 === 國立臺灣科技大學 === 營建工程系 === 92 === The long tunnel construction plays a important role in Taiwan freeway networks. The overburden cover for Snow Mountain tunnel and Taiwan eastern tunnels are deeper than before. Understanding the complicated excavation mechanisms under deep overburden is needed for long tunnel planning, designing and construction. The section of Taiwan eastern tunnel are simulated by using a three dimensional numerical code FLAC3D in the study. At first, the overburden influence on tunnel behavior are investigated. The location of tunnel roof, corner, and invert are selected as analytic points, and their stress, deformation and plastic zone with bench cut during tunneling are analyzed. The analytic results show that the adjustment of stress, deformation and plastic zone during excavation are large for deeper overburden. At second, preliminary studies of dynamic effect are presented .by analyzing the stresses and plastic bearing dynamic simulation. Longer dynamic duration will induce higher stress increment on supports
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