EVALUATING THE INFLUENCE OF CLIMATIC FORCES ON ROCKFALL INITIATION

Rockfall poses serious hazards to safety and infrastructure along both excavated and naturally exposed rock slopes. Significant progress has been made in predicting time-to-failure for large-scale, progressive slope failures using monitoring techniques such as ground-based radar. However, small-scale, brittle rockfall events typically occur with little to no detectable precursory movement, which has precluded the prediction of such events by similar means. It is intuitively known throughout the geotechnical community that environmental forces (e.g. heavy rainfall) often lead to increased rockfall, but quantitative documentation of these relationships is lacking. The issue has become increasingly urgent considering the rising magnitude and frequency of weather events associated with climate change. Empirical correlations between environmental forces and rockfall events could be a critical first step in quantitatively predicting the likelihood of increased rockfall resulting from climatic perturbations, which has the potential to increase safety in a variety of industrial and natural environments. Recent advancements in real-time rockfall detection using thermal video in open pit mines by the University of Arizona’s Geotechnical Center of Excellence (GCE), have allowed for continuous spaciotemporal monitoring for rockfall events along excavated highwalls over periods of up to several months. Over 45,000 hours of thermal video have been collected in eight open pit mines across western North America using the GCEs thermal imaging trailer, specifically to assess the viability of using thermal video in rockfall detection and tracking. Numerous rockfall events have been documented from the thermal video archive, which includes the time, place, and weather conditions. Coupling these documented rockfall events with the concurrent environmental data such as precipitation, temperature (freeze-thaw), wind, and solar irradiance can illuminate potential correlations between rockfall occurrences and these environmental factors. Here, we present preliminary correlations between rockfall events observed using thermal imaging at several open pit mines in North America and the corresponding local climatic forces, with the ultimate goal of advancing the predictability of rockfall by understanding the factors that contribute to rock destabilization.