Abstract:

In order to take the effects of the profile on the trajectory of rockfall into account, the boulder is approximately supposed to be elliptic. According to the five common forms of rockfall, containing rolling, slide, collision, freely falling body movement and parabolic motion, the formulae to calculate the velocity of different kinds of motion are proposed respectively. When the boulder collide with earth, the elastoplastic deformations of earth are considered. Coefficient of restitution, which relates to the velocity before collision, the shape of boulder and geomaterial of earth, is presented. Moreover the impulse force due to collision are obtained on the basis of contact mechanics. Besides, the criterion of continuous rolling is put forward. Finally, an illustrative example is given to show the capability of the presented model to predict the rockfall trajectory of Shoulishan in Wanzhou of Chongqing.

Key words: elliptic boulder, elastoplastic collision, coefficient of restitution, movement trajectory