THE EFFECT OF MATERIAL PROPERTY VARIATION ON ROCKFALL MOVEMENT

Abstract

Rockfall movements are characterized by 3 key indicators: runout distance, M_l, maximum kinetic energy, M_e, and maximum jumping height, M_h. This study investigates the influence of material property variations on rockfall movements and proposes a highly accurate prediction model based on the traditional Response Surface Methodology (RSM). Five material properties are considered, they are young’s modulus for rock, E_rock , density for rock, ρ_rock , young’s modulus for slope, E_slope , coefficient of restitution between rock and slope, COR, and kinetic friction coefficient between rock and slope, μ_f . When comparing rockfall movements without material property variations to those with material property variations, it is observed varying degrees of difference. That is, the mean value of difference shows little influence but the standard deviation (SD) of the difference of runout distance varies from 9% to 35%, maximum kinetic energy varies from 0% to 2% and maximum jumping height varies from 8% to 86%. Additionally, a developed approach based on the traditional RSM called ‘MCS+RSM’ is proposed by using fewer input material parameters to reach a higher fitting accuracy. Specifically, compared to the 5 input material parameters in the traditional RSM, the prediction using MCS+RSM only requires 1 or 3 parameters. For the same number of sample points as the traditional RSM, MCS+RSM can accurately predict the mean and the SD value of runout distance, M_l, and maximum jumping height, M_h, while the traditional RSM has a large error in the prediction of SD value.