ABSTRACT
With the existence of a high groundwater level in the Bangkok sand aquifer, deep MRT station excavation poses a significant risk of excavation instability and water ingress. In this paper, a groundwater controlling method during excavation of the Bangkok MRT Orange Line East Project is presented, supported by field pumping test observations. Deep well dewatering systems were installed inside the excavation area to decrease groundwater and maintain relatively dry environment during excavation. Prior to execution excavation in confined sand layer, pump-ing tests were conducted, and the test results demonstrated that diaphragm cut-off walls and de-watering can effectively control groundwater during excavation. The number of deep wells and amount of groundwater inflow were then estimated by back-analysis approach using pumping test results and dewatering records. Moreover, this finding can serve as a reference for evaluating the number of pumps in similar projects.
