Fundamental laboratory experiments of siphon drain for slope stabilization

Controlling the groundwater level in the slope can prevent the occurrence of landslides and maintain the stability of soil slopes. This paper aims to present the results of laboratory siphon drain experiments to evaluate the siphon drain effectiveness in lowering the water table in a model slope under different experimental conditions. The objective of the experiments was to observe and document the effect of the siphon well location, the siphon well spacing, and the initial groundwater level on the discharge and groundwater level. Five siphon pipes connected to five flushing units were used to extract the water from the slope. Several plastic manometer tubes were installed to monitor the water table. The laboratory experiments demonstrate that the siphon drains decreased the water level in the slope under different siphon well locations. The water seeping out of the slope toe decreased as the water extracted by the siphon drains increased. However, the siphon drains are useful to decrease the water level in the wells with a high-pressure head. Under high water due to rapid water level rise, the siphon drain can reduce the water table level within the slope up to 10 cm at the steady-state condition. In contrast, the siphon drain can effectively prevent the increase of the water table and further development of the seepage face area at the slope toe under low water level associated with a slow increase of water level.