Centrifuge Modeling of Embankment Failure due to Underground Cavity and Its Electrical Resistivity Monitoring

In this paper, embankment or levee failure due to the interaction between a cavity within an embankment body and high water level was simulated in a centrifuge test and monitored by electrical resistivity tomography (ERT) survey technique. As the centrifuge modeling is an effective research tool for levee stability analysis and the ERT survey is generally adopted in field for health monitoring of levee, physical modeling of levee stability problem and its monitoring by the ERT survey in the centrifuge provides a great opportunity for researchers. Initially, 1 g preliminary test was performed for simulating the underground cavity using a buried ice block to ensure the simulation of such cavity in the centrifuge model. Subsequently, 20 g centrifuge test was performed. At the 20 g-level, over the three stages’ water level in river side was maintained to simulate expansion of the underground cavity with increase in groundwater level. Continuous ERT survey was simultaneously conducted to monitor the variation of internal state of the embankment body. During the final high water level, subsidence of levee surface occurred at the vertical location on top of the cavity which can lead to embankment failure. The ERT results (two dimensional contour plots) from the centrifuge test correspond well to the expected process of levee subsidence caused by upward development of inner cavity by showing definite resistivity difference between the cavity and adjacent soil. From the centrifuge test, it is concluded that the cavity within the embankment body could induce failure upon interacting with the high water level, and the ERT monitoring could effectively capture the geotechnical process which shows the upward development of underground cavity.