Groundwater Control Measures for Deep Excavation of Bangkok MRT

Over the past few years, Mass Rapid Transit (MRT) Projects have been implemented in Bangkok as part of a master plan for the city and its surrounding areas. However, the underground construction of the MRT in Bangkok has become increasingly complicated due to the effects of the groundwater rebound in underlaid sand layers, which has posed a significant challenge in designing and building underground structures. Most of underground structures in the MRT projects are located deeper than the piezometric profile within the sand aquifer, which is currently at approximately 13 m deep from the ground level, making them vulnerable to hydraulic uplift and piping failures. Depending on factors such as station configuration, excavation level, and soil strata at the site, various methods including diaphragm cut-off wall, staged excavation, blanket grouting, and dewatering have been considered on a site-by-site basis and presented in this paper. This paper focuses on groundwater control measures for the MRT Blue Line Extension Project Contract 2 and the MRT Orange Line East Project Contract E1 and E2 and aims to serve as a reference for practitioners in the construction industry who are involved in deep excavation work with high groundwater pressure.