THE INFLUENCE OF ROCK SHAPE AND INITIAL ANGLE VARIATION ON ROCKFALL TRAJECTORY

Abstract

 The rockfall trajectory is affected by a number of parameters such as the material properties of rock and slope, slope geometry, rock initial condition, etc. The rock's initial condition such as initial angle and rock shape are unknown parameters and spatially variable parameters. This study investigates the influence of rock shape and initial angle variation on the rockfall trajectory. Under a slope model with the height of H = 15 m and an angle of 50°, the rockfall trajectory of nine rock shapes reflecting the flatness and elongation is released under different initial angles under Monte Carlo Simulation (MCS) using the Discrete Element Method (DEM). The 100 MCSs can ensure the error of reach probability within 0.001 considering rock shape and initial angle variation. The simulation results indicate that cuboidal compact rock shape tends to have concentrated and longitudinal trajectory distributions, whereas elongated or flattened shapes result in a wider and shorter trajectory distribution. Additionally, through mode analysis, a main region below the rock source is identified. This main region, with a width of 1.3 𝐻 and a length of 1.9 𝐻, captures 98% of the trajectory distribution, irrespective of variations in flatness and elongation of rock shapes.