Fundamental study on impact response of sand cushion by distinct element method

This paper presents a computational approach for the impact response of the sand cushion under a falling rock by using distinct element method (DEM). At first, the static loading test and falling weight test for the sand cushion are performed by using a small size model. It is found that the impact load of a sand cushion can be estimated by using the spring constant of sand obtained in the static loading test. Secondly, the relation between the spring constant of sand and the fictitious elastic modulus of a sand element in DEM is found and the impact response analysis is performed by combining the DEM with Rigid Body Spring Model (RBSM). It has been confirmed that this computational approach can estimate the impact response of a sand cushion by comparing with the experimental results. Finally, the actual size impact tests have been simulated by this approach. It has been found the weight impact load is about 2 times smaller than the transmission impact load and the transmission energy factor is about 6approx.13% in the case of the span length of H type beam 8 approx.12 m and sand cushion 90cm.