Model tests for studying the failure mechanism of dry granular soil slopes

The aim of this study is to investigate the behavior of sandy soil that has collapsed due to slope failures as well as to examine the influence area resulting from the failure. A model slope composed of three sections was employed to perform tests. The tests were conducted on various combinations of slope angle, slope height, slope surface condition, and the relative density of soil.Slope failure was induced by lifting up a retaining plate to cause the soil to collapse. Images of the sliding mass were taken by three cameras from different positions. The series of images clearly displayed the movement and development of granular flows. We then observed and measured the final profile of the soil and the shape of deposition area.The displacement of soil was measured by particle image velocimetry (PIV). Based on the measured displacement of flow, the front velocity of the flow was obtained. The slope angle and the internal friction angle of soil were found to be the most significant factors influencing the front velocity. Furthermore, a simplified equation based on Newton's law of motion is developed to predict the run-out of the flow. Comparison is then made between the measured and predicted run-out distances, and they are generally in good agreement.

Research Highlights
► Model test was used to investigate the failure mechanism of sandy soil slopes.
► PIV was employed to analyze the moving behavior of the granular flows.
► A simplified solution is developed to predict the run-out distance of the flow.
► The required parameters of the simplified solution are based on test results.
► Comparison made between the predicted value and the measurement is generally good.