Abstract: In order to explore the influence of the relative positional relationship between the dynamic load and the long axis of the elliptical cavern on the characteristics of impact rockburst, a cuboid sample with an elliptical hole is prepared. With two positional relationships of disturbance direction parallel or perpendicular to the long axis of the elliptical cavern, the elliptical cavern impact rockburst experiments are carried out. With the aid of video recording device, the characteristics of the impact rockburst of the elliptical cavern are discussed in terms of damage process of rockburst ejection, ejection speed, failure mode and fragment size. The experimental results show that the rockburst processes of the two samples with different positional relationships are the same, and the rockburst pits are all V-shaped. The initial failure stress, rockburst stress, rockburst ejection velocity, rockburst pit size, fragment mass and proportion of coarse-grained fragments of the samples whose disturbance direction is perpendicular to the long axis of the ellipse are smaller than those of the samples whose disturbance direction is parallel to the long axis. The fragment characteristics of the samples whose disturbance direction is perpendicular to the long axis of the ellipse are mainly presented as thin stripes. The samples whose disturbance direction is parallel to the long axis of the ellipse can significantly improve the bearing capacity of the cavern structure. However, the rockburst phenomenon is more severe and its debris characteristics are mainly of thick plate.

Key words: elliptical cavern, long and short axes, impact rockburst, ejection velocity, fragment characteristics