Risk zoning and targeted mitigation of high-altitude rockfalls in strong earthquake areas based on 3D kinematics and improved evaluation model

Abstract

High-altitude rockfalls in strong earthquake areas are characterized by high concealment and destructive power. Long-term natural weathering or human activities can easily create secondary risk exposures. Traditional 2D kinematic calculations and static evaluation methods struggle to accurately delineate threat zones in complex terrain. Taking a high-altitude rockfall behind a centralized resettlement site in a strong earthquake area in Southwest China as a case study, this paper proposes a comprehensive evaluation and protection framework of “3D Kinematic Simulation—Engineering Risk Zoning—Targeted Mitigation”. First, UAV photogrammetry was used to construct a high-precision 3D surface model, and 3D numerical simulation software was utilized to simulate the kinematics of unstable rock masses, quantifying dynamic parameters such as trajectory density, kinetic energy, and bounce height. Second, considering the dense residential areas and infrastructure below, the “Element at Risk Importance” indicator was introduced to construct an improved multi-factor weighted engineering risk evaluation model. Grid-based quantitative risk zoning was achieved under a GIS platform, accurately locking onto the extremely high-risk funnel zones. Finally, addressing the practical engineering pain point where existing 4m-high passive protection nets were artificially damaged to form 25 holes, the traditional approach of total reconstruction was abandoned. Instead, a targeted reinforcement scheme of locally adding passive nets was proposed based on the risk zoning results. This study not only overcomes the limitations of spatial hazard prediction for high-altitude rockfalls but also provides a novel paradigm for the scientific evaluation and economical maintenance of damaged disaster mitigation engineering in mountainous areas.