Rockfall shed tunnel is one of the effective measures for rockfall disaster prevention in the mountain area.Determination of rockfall impact force is the key point in rockfall shed tunnel design.The variation law of rockfall impact force under the impact of rockfall weight

height and impact angle was studied based on the impact experiment.It was found that the rockfall impact force increases when falling height increases and impact angle reduces

and the increment ratio is up to 80.02%.The variation amplitude of the impact force with falling height is smaller for light rockfall and is larger for heavy rockfall.The impact force grows by 182.10%from the minimum value to the maximum value.The influence of rockfall weight is obvious than that of impact angle on the impact force.The increase rate reaches 48.99%.It was concluded that the rockfall weight is the most important factor that affects the value of impact force

followed by rockfall height and impact angle sequentially.The impact force calculation formulas of rockfall on the shed tunnel were derived by regression analysis at the end of this paper.The regression relation between the impact force and influence factors was highly significant through variance analysis.So the calculation formula can be used in impact force calculation of rockfall shed tunnels.