Model test on deformation and failure behaviour of arching-type slope under excavation condition

Excavation is one of the common triggers for slope failures. Loss of support at the toe of a slope due to mining excavation can cause unloading of geomaterials close to the excavated area and stress redistribution. The deformation behaviour of arching-type slopes is different from the deformation behaviour of common dip slopes. Therefore, it is necessary to study the deformation and failure mechanism of slopes under excavation conditions. In this study, a series of physical model tests was conducted on arching-type slopes with different slope angles and relative densities. The physical models were monitored by various instrumentation, such as a digital camera, a high-speed camera, earth pressure gauges, and a multi-smartphone measurement system. The deformation characteristics during excavation were analysed by using particle image velocimetry (PIV). The results show that the yielding area, including the arch-shaped large deformation area and upper small deformation area, and two sides of unyielding areas were clearly observed and considered features of arching-type slope deformation related to the arching effect. In arching failures, slopes with higher relative densities can generate larger initial kinetic energy. Toe failure, sliding failures, tension cracks, and bulking failure subsequently occur in the final failure. The equations for the maximum excavation width and the curve of the stable arch of arching-type slopes are verified.