Hydraulic Joint Splitting Failure Mechanism of Anti-dip Rock Slope Controlled by Regional Joints—Taking the “8·11” Da’anshan Rock Collapse in Beijing As An Example

In this paper, the “8·11” Da'anshan anti-dip rock collapse is taken as the research object. Through the investigation of regional joints, collapses, slope structure characteristics and dangerous rock mass deformation characteristics in Da'anshan area, the hydraulic splitting theory is used to analyze Da’anshan collapse mechanism. The results show that under the joint action of regional joints and differential weathering, a large number of high-steep 20~50 meter high anti-dip rock slopes are developed in the Da'anshan area, which provides favorable conditions for the occurrence of collapse disasters. Meanwhile, the spatial combination of the joint fracture network and the hard rock formation provides good geological conditions for rainfall infiltration, migration and storage. When encountering rainfall, the rainwater seeps along the rock mass and is filled with fissures. In the short-term after the rain stops, the cracks are still hydraulically split by the high water head, cause the cracks to expand and penetrate, and eventually lead to the instability and collapse of the dangerous rock mass.