ABSTRACT
Rockfall has long been a serious problem to mountainous regions of the world. The design of rockfall mitigations requires estimations. on the horizontal and vertical travel distances of the probable rockfall events. The most popular approach for estimations is the use of computer programs in rockfall simulations, and it is important to note that the main parameter controlling the prediction is the coefficient of restitution. In view of this, we have recently done experiments simulating boulders falling onto soil slopes. We find that normal and tanegntial components of the coefficient of restitution (Rn and Rt ) increases with the dry density of the soil when the moisture content is less than the optimum water content, which leads to optimum soil compaction. When the optimum water content is exceeded, both Rn and Rt , remain roughly constant regardless of the values of the dry density of the soil.
