| Summary: | 碩士 === 國立高雄第一科技大學 === 營建工程研究所 === 100 === The new austrial tunneling method (NATM) is widely used in the rock tunneling. The construction concept of NATM was systematically introduced by Chinese Institute of Civil and Hydraulic Engineering in Taiwan since 1980. The NATM was firstly used to the construction for the Tze chiang tunnel of the domestic railroad in 1982 and were subsequently used for some rock tunnels in the construction. The NATM has now become a major construction for the rock tunneling.
Because of the thinner overburden in general on the tunnel portal, it is difficult to form the self-retaining of arches, and has great difficulty as well as risks during the construction especially in the site with poor geology.
Three tunnel portals under investigation in the study are located near seashore in northwestern part of Chai Shan mountain in Zuoying of Kaohsiung. Because of the weak colluvial soil consisted of the weathering mudstone and limestone presented and a huge rainfall encountered, the collapse of the tunnel portals were occurred. The types of collapse are included the settlement, slope collapse. crown collapse and squeezing of the tunnel portals. The purpose of this study is to carry out the investigation of the causes on the collapse of the tunnel portals and the proposal of countermeasures. It attempts to provide a reference for the similar poor geology where the collapses of tunnel portal are occurred.
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