| Summary: | 碩士 === 國立高雄應用科技大學 === 土木工程與防災科技研究所 === 96 === ABSTRACT
Regarding development of underground structure, the need of extremely large and deep excavations was found. In this study, a case history of a large-scale circular cofferdam excavation in Kaohsiung retained by diaphragm wall is explored. Back-analyses based on pumping record in this case are conducted so actual permeability of soils are interpreted. In addition, engineering performances of the excavation are examined in order to indicate influences on ground and structure responses from diaphragm walling. Discussions of the relationship between lateral and vertical movements are included in this paper so it is expected to provide a useful reference to similar excavations in Kaohsiung later on.
In this study, back-analyses indicate permeability of the 1st and 3rd layer of sand varies from 5×10-3 to 7×10-3 cm/sec. On contrary, permeability of the 5th layer of sand is much smaller, varies from 1.25×10-3 to 1.75×10-3 cm/sec.
Further, observations in this study show the maximum building settlement reaches up to 0.018% of depth of the wall. Considering movements induced by excavation, the maximum lateral wall movement is approximately 0.13% to 0.17% of the excavation depth and the maximum building settlement is 0.15% of the excavation depth. Lastly, the influence zone on surface level behind the wall is 4 times of the excavation depth.
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