Comprehensive study of the Beijing Daanshan rockslide based on real-time videos, field investigations, and numerical modeling

Abstract

The depth-integrated model has been applied to the simulation of various kinds of earth surface flows. However, there are few studies that focus on the difference between the associated dynamic processes and the computational results. The recent Daanshan Village rockslide, recorded by 3 real-time videos from different view angles as well as pre-slide images and detailed field investigations, offers an opportunity to provide some new insights into this issue. In this paper, the failure mechanism and dynamic processes behind the Daanshan rockslide were analyzed in detail and simulation results obtained from depth-integrated modeling in both the vertical and rotated coordinate systems were compared with the videos and field investigations. The field investigations reveal that the rockslide was essentially controlled by the sedimentary unconformity interface and the interbedded black mudstone layers, and triggered by intense rainfall. The comparisons indicate that the simulated trimlines generally matched the real trimlines at each second, but at the initial stage, the simulated velocities are a little large. With respect to the final deposition area, the simulated runout distance and trimlines matched well with the field investigation results, and the accuracy estimated by the contact area percentage of the maximum impact area reached 91.46%. The simulation results obtained from the vertical and rotated coordinate systems show significant differences. The simulation accuracy of the rotated coordinate system was 91.46%, while for the vertical coordinate system it was 84.69%, demonstrating that the rotated coordinate system should be used, or the vertical acceleration should be modified to obtain credible results. This comprehensive analysis verified that the depth-integrated model can access both rockslide processes and the final deposition area. It is pointed out that the rotated coordinate system can obtain better results than the vertical coordinate system in areas with steep slopes, whereas the differences can be neglected when considering gentle slopes.