Remote sensing identification and hazard assessment methods for spoil sites

Spoil sites, as loose accumulations, are prone to instability after disturbances and are a serious threat to the safety of downstream communities. This research aims to rapidly and accurately assess the potential hazards of the numerous spoil sides. An integrated approach that combines spatial, aerial, and ground techniques was developed to rapidly identify and interpret the key factors influencing the stability of spoil sites. Subsequently, based on the results of numerical simulation of multiple combinations of unfavorable working conditions by the material point method, a hazard assessment methodology for spoil sites is proposed, which combines the limit equilibrium method with the improved hierarchical analysis. The proposed method is applied and validated on spoil sites along an expressway. The achieved results reveal that remote sensing combined with unmanned aerial vehicle (UAV) verification technology is capable of quickly and accurately identifying the critical elements of spoil sites. The hazard assessment of the spoil site is represented by the hazard coefficient (P), where 0 < P < 1 indicates safety, 1 ≤ P < 5 signifies instability, and P ≥ 5 represents extreme instability. The effectiveness of the proposed assessment approach is then verified through the on-site validation, which provides a vital reference for rapid identification and batch assessment of spoil sites.