Numerical Impact Response Analysis of Rockfall Protection Galleries

In Japan, rockfall protection galleries have been designed on the basis of the allowable stress design concept. To establish a rational impact-resistant design procedure for the galleries, an understanding of both elastic and elasto-plastic dynamic behavior of the galleries under impact loading is required. In addition, an evaluation method for the load-carrying capacity is also necessary. To meet these requirements, a three-dimensional numerical analysis method is proposed and its applicability is verified by comparing it with the experimental results of a prototype reinforced concrete girder with a sand cushion under falling-weight impact loading. Subsequently, using a prototype gallery with a sand cushion subjected to falling-weight impact loading, numerical simulations were conducted by varying the magnitude of input impact energy. The analysis of impact force, penetration of the weight into the sand cushion, displacement of the roof slab, crack patterns, and the safety margin of the gallery are discussed.