Research on rockfall movement characteristics and protective measures of dangerous rock zone of Changyang Jigong rock

Addressing the persistent rockfall hazards along the Jigong unstable rock zone in Changyang County, Yichang Province, which have long threatened the operational safety of both the highway and the Qingjiang waterway, this study employed UAV photography and field survey data. By using Rocfall and Rockfall Analyst software to simulate rockfall trajectories, and applying the entropy weighting method to determine factor weights, a multi-factor overlay analysis yielded a hazard ous zoning map for the unstable rock zone. This analysis proposed the construction of an open-cut tunnel as a protective measure. Results indicated that the primary failure mode of the dangerous rock zone was free-falling rock. The majority of rockfalls in the central-eastern section struck the highway directly, while others leaped over the roadway platform and tumbled into the Qingjiang River. Conversely, most rockfalls in the western section ceased the movement within vegetation-covered areas, posing non threat to passing pedestrians or vehicles on the highway. The steeply sloping areas adjacent to the road in the central-eastern zone constituted an extremely high-risk zone. Therefore, an open-cut tunnel with a buffer layer at its crown should be constructed in this area. Comparison of simulation results before and after implementing protective measures verified that this approach could effectively block falling rocks, ensuring the operational safety of both the highway and the Qingjiang river waterway.