Analysis of Rockfall Hazards Based on the Effect of Rock Size and Shape

Abstract

Rock sizes and shapes influence the trajectories of rockfall. Thus, this study examined the bounce height and runout distance of falling rocks on the basis of different rock sizes, rock shapes, and ground surfaces. A laboratory experiment of rocks with various sizes falling from 35°, 45°, and 60° slope angles and vertically on different ground surfaces was conducted in this study to understand the mechanism of falling rocks. RocFall 5.0 (Rocscience), a 2D rockfall numerical simulation program, was used to perform the probable bounce height and runout distance for various rock shapes on different ground surfaces. The laboratory experiment and a numerical simulation were compared to validate the applicability of laboratory testing in rockfall assessment and calibrate the coefficient of restitution, which is a critical parameter in bouncing blocks. Results indicated that steep slopes and hard ground surfaces cause a high bounce height of falling rocks. Moreover, light rocks bounce higher than heavy rocks, and rocks with round shapes bounce high initially and then roll further away from the falling slope. Therefore, the influence of rock sizes and shapes and impact surface material must not be omitted in investigating rockfall protective measures.