Prediction of Shallow Failure on a Slope Using Volumetric Water Content Gradient Characteristics

Landslides that occur near residential regions are most commonly a result of shallow slope failure, which takes place as a consequence of heavy rainfall during the monsoon season, causing loss to human life and property. In this study, the characteristics of the volumetric water content (VWC) gradient were analyzed to predict shallow slope failure which was reproduced based on flume experiments performed at various slope conditions. The VWC gradient values were calculated for each measurement position and slope depth. Moreover, the VWC gradient characteristics during the occurrence and nonoccurrence of shallow slope failures were compared to those of an actual site that did not undergo slope failure. Our results show that the probability of failure increases with an increase in the VWC gradient value. Additionally, early warning criteria are proposed by dividing the range of the VWC gradient value into four stages in which the failure rate rapidly increased. Full-scale flume experiments were performed to simulate an actual site in terms of its scale, and the appropriate sensor installation positions were proposed to effectively predict the probability of failure.