| Summary: | 碩士 === 國立臺北科技大學 === 土木與防災研究所 === 102 === In the retaining wall design for basement excavationi, buttress wall has been adopted along with diaphragm wall. However the diaphragm wall has to be constructed on the base of panel. Two adjacent primary panels are placed leaving out the secondary panel in between. Following the two primary panels, gaps are closed by the secondary panels. Primary panels have smaller width than secondary panels due to the use of end plates. The type of joint between diaphragm wall and buttress wall includes T-shape and non T-shape. There are advantage and disadvantage for each type joint used. In this study, the trench excavation, steel cage construction and concrete placement were recorded for both types of joints from several construction sites. Based on the information collected form these projects, the advantage and disadvantage for each type of joint will be discussed and compared in term of ease of construction, trench wall condition and the ability to minimize the deflection of diaphragm during excation.
During various stages of excavation, the wall defects were observed and were compared with the results of concrete take versus wall depth recorded in concrete placement and trench wall condition recorded from sonic logging. It is verified that the concrete take along with the trench wall condition can be used to estimate the quality condition of diaphragm wall and provide the information about what type of defect in diaphragm wall. Therefore any immediate measures can be taken before basement excavation to prevent any catastrophic foundation failure from happening and to reduce the possible property damage and human life loss.
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