Abstract: The characteristics and influencing factors of the offset ratio of rockfall movement were researched by model tests. Factors including falling height,slope type,slope cover,and rockfall mass influencing on the offset ratio were analyzed. The results indicate that the offset ratio of rockfalls from different heights (which means different velocities) increases with the increase of velocity;while the offset ratio of rockfalls from the top of the slope (0cm) is strongly random and has no regularity. The offset ratio on stepped slope is larger than that on steep-slow slope. When the slope cover is harder,the offset ratio is larger;and when the mass of rockfalls is smaller,the offset ratio is larger. The value of offset ratio is within the range of 0.5. In practical engineering,large velocity,stepped slope,small rock mass,and hard slope cover will result in big offset ratio and randomness. Therefore,in passive prevention,larger range of lateral threat should be considered. The research provides reference for rockfall protection.

Key words: rockfalls, offset ratio, model test, sensitive factors