Research on Normal Restitution Coefficient of Rockfall Collision

Abstract

In the process of designing the engineering protection, the accuracy of calculating the trajectory of rockfall movement mainly depends on the value of normal restitution coefficient. The rockfall collision process is captured by DIMS9100 analysis system in the indoor physical model test where velocity parameters under different rockfall size, slope gradient, incident velocity and slope material conditions are collected. Then the normal collision restitution coefficient can be obtain by analyzing velocity parameters before and after collision. The results show that the normal restitution coefficient is not significantlyassociated with the size of rockfall and the incident velocity, but only related to the slope and the mechanical properties of slope materials; The material change from soil layer, simulated lawn to concrete, the corresponding stiffness increases as slope gradient of the soil layer, simulated lawn and concrete increases respectively, and therefore the normal recovery coefficient also shows an increasing trend. When the slopegradient and slope materials are considered in practical engineering applications, the normal restitution coefficient range of rockfall collision is 0.32 ~0.62 and the value of normal restitution coefficient is smaller than that of the existing data. It indicates that thevelocity decreases greatly in the normal direction during the test.