The Study of the Behavior of Deep Excavation Induced by Dewatering in Sand

• Main Authors: Fu-Yuan Chang, 張福原
• Other Authors: Bin-Chen Hsiung
• Format: Others
• Language: zh-TW
• Published: 2007
• Online Access: http://ndltd.ncl.edu.tw/handle/41205331986359387135

碩士 === 國立高雄應用科技大學 === 土木工程與防災科技研究所 === 95 === In order to proceed the construction as well as to preVent the uplift failure, it is quite often that dewatering in deep excavations in sand is necessary. Thus, it is essential to complete a study to understand influences on adjacent ground and structure caused by the dewatering. In general, theories of “well” and “half-infinite space” were applied for analyses of dewatering. However, as the influences from retaining structures are excluded, the predictions using such theories are too conservative in the simulation related to dewatering in deep excavations. First, in this study, a case study of dewatering in an excavation for an underground tank was selected and a back analysis using finite element program SEEP/W is carried out based on this case. An additional set of analysis accompanied with Theis theory is established for the comparison. It was found that the predicted draw-down curve caused by dewatering from both analyses is similar. Second, one more case from an excavation in Kaohsiung rapid transit systems was chosen for the back analysis in this study. It was concluded that using SEEP/W with steady-state analysis and an adequate estimation of flow channels could predict actual quantity of water-pumping on site successfully. At last, a full improvement of soil inside the excavation is considered to preVent the effects on ground and structure outside the excavation generated by dewatering. The thickness of improved soil is 3.5m and it was carried out starting from toe of retaining wall. Such arrangement eliminated the influence on ground and structures outside the excavation effectively. However, this measure could not reduce the effects on ground and structures outside the excavation if only soils near the retaining structure were improved.