Numerical simulation on dynamic response of the shed-tunnel structure under multiple rockfall impacts

To exploring the dynamic response characteristics of the shed-tunnel structure under multiple rockfall impacts, an FEM-SPH coupled numerical model is established based on ANSYS/LS-DYNA and is also tested with the data before. Then, the model is combined with the full restart technique to study the effects of the shed-tunnel structure dynamic response under multiple rockfall impacts by considering four factors, e.g., rockfall impact velocity, rockfall mass, impact angle and rockfall shape. The results show that the impact force, buffer top impact displacement, roof displacement and plastic strain of the shed-tunnel are positively correlated with the rockfall mass, velocity and angle. The impact force, roof displacement and plastic strain of the shed-tunnel structure generated by the cuboid rockfall impact are all larger than those of the spherical rockfall, and the impact displacement generated by the spherical rockfall impact is larger than that of the cuboid. For the cuboid rockfall, the impact displacement, roof displacement and plastic strain are negatively correlated with the contact area. Under the multiple rockfall impacts, the peak impact force usually increases firstly and then tends to be stable.