Dynamic analysis of rock-fall impact on shed tunnel structure

Shed tunnel structure was taken as prototype, and the contact force, displacement, damage, and energy of shed tunnel under rock-fall impact were studied.Rock-fall was simplified to rigid sphere, surrounding rock and soil were reduced to ideal elastic materials, and concrete was regarded as elastic-plastic material.The dynamic responses of rock-fall impact on shed tunnel structure at different speeds and incident angles were simulated by using ABAQUS finite element.Analysis result shows that when incident angle is unchanged, the greater rock-fall speed is, the greater the displacement is.When rock-fall speed is constant, the smaller rock-fall incident angle is, the greater the displacement is.The worst damage of concrete protective structure occurs at rock-fall contact area, the second damages are inclined leg pillar top and beam in connection with pillar, and the intensities of pillar top and beam joint should be strengthened in practical projects.Impact energy is mainly absorbed and consumed through the concrete protective structure of shed tunnel, the absorption and consumption of soil cushion layer are very limited.To alleviate the damage of rock-fall impact on the concrete protective structure, energy shock absorber can be added at shed tunnel bearing place.