Influences of stone content on stability of gravel soil slope based on DIC analysis

To study the influence of stone content on the stability of gravel soil slopes, static overload tests were carried out on slopes with different stone contents. By combining model tests combined with digital image correlation （DIC） technology, the deformation of the soil body in both the whole field and local field of the slope was analyzed. The findings indicated that the stone content had a significant controlling effect on the bearing capacity and deformation characteristics of gravel soil slope, and two threshold values of stone content, i.e. 20% and 70% were found based on the ultimate bearing capacity. Further analysis was conducted at the meso-scale to understand the deformation behaviour of local soil and the movement of gravel during the shearing process. The local soil was found to exhibit the shear dilatancy effect, resulting in a significant increase in porosity in the shear zone. By tracing the movement of gravel and its surrounding sand particles in the local soil, it was found that the gravel can affect the development of shear zone, and five modes of shear zone surrounding stone were summarized: unilateral rock bypass mode, bifurcation mode, crossing rock and bifurcation composite mode, bifurcation and unilateral rock bypass and crossing rock composite mode, and unilateral rock bypass and crossing rock composite mode. The research results provided a reference for further understanding the inherent mechanism of gravel soil slope instability.