Rockfall hazard assessment and governing strategy for a cliff feature zone based on the high-resolution online images and terrain analysis

Abstract The geological disaster caused by the slope landslide rockfall has some significant properties, such as suddenness, unpredictability, higher harmfulness. In this paper, a cliff feature zone in Guizhou Province of China is selected as a case, the topographic data in the study area are obtained by the field survey, and the slop angle distribution (SAD) method with the topographic map is adopted to identify the potential rockfall source zone. The Rockfall Analyst software is applied to simulate the trajectory, frequency, height, and energy of the slope landslide rockfalls, and the accuracy of the rockfall model is verified by comparing the simulation results with the actual accident. Then, the rockfall hazard assessment is conducted for the whole Jinfeng street, and relevant governing strategies are proposed. The results show that the rockfall source zone area in the Jinfeng Street validated by using the SAD method with the rock outcrops in the topographic map is identified as 522,316 m2, which is 0.8% of the total area. The building area in the hazard zone are 81,105 m2, and the percentage of building area in the high-hazard and ultra-high-hazard zone reaches 25.6%. To reduce the hazards caused by the slope landslide rockfalls, according to the Code for Design of Rock Retaining Wall Engineering in Geological Hazards (T/CAGHP060 -2019), a stone retaining wall with the height of 5 m is built, and its stability is verified. The results indicate that after adding the stone retaining wall, the rockfall hazard zone area decreases to 2,580,371 m2, there is no ultra-high hazard zone, and the building area in the rockfall hazard zone reduces to 50,432 m2. After adding the stone retaining wall, for the residents who are still in the high hazard zone, a unified relocation strategy is recommended to ensure the safety of residents’ lives and property.