Mechanics and modelling approaches of rockfall: a comprehensive review for hazard mitigation in hill roads

Rockfall, a rapid and high-impact landslide phenomenon, poses significant risks to lives, infrastructure, and transportation routes in hilly and mountainous regions. This hazard is characterized by sudden occurrences, widespread impact, fluctuating magnitudes, randomness, and a high fatality rate. The present study aims to provide a knowledge base for stakeholders in infrastructure projects in hilly regions by consolidating findings from reported studies on rockfall. Through a review of reported studies, three key aspects of rockfall are discussed: kinematics, source zone identification, and modelling approaches. Factors influencing rockfall detachment, modes of motion, impact force, and fragmentation are discussed, along with challenges in identifying potential source zones and proposed advanced methodologies for more precise identification and monitoring. Various modelling approaches for assessing rockfall characteristics and trajectories are evaluated, emphasizing the significance of numerical simulations and 3D modelling for accurate evaluation and mitigation strategy assessment. The study also highlights limitations in current modelling approaches and outlines future research directions including the integration of vegetation-related factors, incorporation of fragmentation phenomenon, utilization of advanced technologies for source zone identification, and advancements in rockfall detection and prediction through deep learning techniques. The ultimate goal is to apprise the stakeholders about present tools and techniques for conducting detailed rockfall trajectory simulation and prediction, so that the most suitable rockfall mitigation and/or protection strategy can be selected and implemented based on the specific characteristics of the site.