Sustainability of Soil/Ground Environment under Changes in Groundwater Level in Bangkok Plain, Thailand

The groundwater level is a significant factor when assessing the sustainability of soil/ground environmental factors, such as bearing capacity behavior and soil surface displacement. Normally, groundwater level changes depend on deep-well pumping in industrial and economic development areas in many countries, especially Bangkok, Thailand. Groundwater level changes are related to pore water pressure changes and soil surface displacement, called land subsidence or rebound displacement. Changing soil strength and soil surface displacement during groundwater level changes depend on many factors. This study analyzes the behavior of soil around a single pile when the groundwater level changes and assesses the behavior of soil displacement when the groundwater level rises to the ground surface after prohibiting groundwater pumping. This research evaluates the behavior of soil by using a centrifuge machine and theoretical calculations (soil displacement analysis only). The results of both the centrifuge test and theoretical calculations were compared with the results from the Department of Groundwater Resources (DGR) and previous research conducted by other researchers. The soil surface displacement behavior in the centrifuge test showed a similar trend compared with the field measurement results of DGR. Meanwhile, the results of the theoretical calculations and the results of previous researchers showed a similar trend regarding the rebound in soil surface displacement. Furthermore, the bearing capacity of a single pile in stiff clay increased when the groundwater level decreased, and the bearing capacity in stiff clay increased further upon groundwater recovery or the rise to the ground surface. In medium-density sand, the bearing capacity increased when the groundwater level decreased and decreased when the groundwater level recovered to the ground surface.