A bouncing ball model of rock falls triggered by earthquakes

摘要

Rock falls are frequently triggered by strong earthquakes, according to Keefer (1984). The procedure for determination of the incoming and outgoing rock velocity on impact with soil is based on the energy balance and the bearing capacity of a circular footing on the soil surface. The bouncing ball model can be used for prediction of rock fall parameters according to the results of analyses of three case histories. The main factors affecting rock fall trajectory are slope shape and ground type near the ground surface, i.e. soil or rock, as stated by Hoek (2006). Rock bouncing may exhibit chaotic behaviour and therefore the outcomes are unrepeatable and unpredictable, except for the extreme values of the rock velocity, jump height and fall distance. Small probability of collision of rock fall with a vehicle on the adjacent road or with a residential house is very significant for the individuals experiencing such collision. Assessed probability of collision may not be reliable because of chaotic nature of rock bouncing.