The Dewatering Reclamation of Deep Excavation in Metropolitan－A Preliminary Study of Kaohsiung Mass Rapid Transit System Project

• Main Authors: Chen, Fuw-Ming, 陳福明
• Other Authors: Ting, Cheh-Shyh
• Format: Others
• Language: zh-TW
• Published: 2005
• Online Access: http://ndltd.ncl.edu.tw/handle/91207111745719991087

碩士 === 國立屏東科技大學 === 土木工程系碩士班 === 93 === Because land resources are limited in metropolitan areas, people continue to develop aerial- and sub-surface space in order to open up more available space. Groundwater flows may be enhanced, however, when deep excavation is carried out during major construction. The method of intercepting the groundwater by pumping and discharge to a drainage ditch is used to solve these problems. This results in a considerable waste of water resources, since construction has been going on for a long time. The rapid transit system in Kaohsiung metropolis is taken as an example in the present paper for discussion on dewatering of deep excavations. Information relating to the current soil situation and basic groundwater data along the rail web were collated from geological survey reports. The pumped quantity from the deep excavation dewatering system can be calculated from the above information, as can the total dewatered amount at subway stations in the rapid transit system. Monitoring wells were established along the rapid transit network before the rapid transit system was constructed, to indicate the long-term groundwater quality and changes in water level. Sampling at fixed locations during construction is used to determine whether or not groundwater was polluted by construction and reclamation. The research showed that a conservative estimate of the total dewatering exceeds 106 m3 for the twenty-seven subway stations on the red and orange lines of the rapid transit system. Water quality meets control standards for second-order groundwater pollution; conductivity reaches 750 mho/cm, total hardness is above 150mg/L, and total dissolved solids exceed 250mg/L. The water is not suitable for drinking in the context of urban development, though it can be used for other environmental purposes and for supplementing groundwater, except when this is to be used for either domestic drinking water or farm irrigation. Keywords: Deep excavation; dewatering system; mass rapid-transit system;groundwater quality