Abstract: In order to understand the failure process of landslide dam, nine sets of flume model experiments were conducted, the depth erosion and tracing of dam breach was further discussed, and the relationship of moving velocity of up-tracing point and breach depth was also analyzed. The results indicated that the angles between the erosion layer and the base bed were changing during the dam failure of non-cohesive landslide dam; The locations of up-tracing and down-tracing point were unfixed,but they could not move to the dam heel; When the slope of the upstream and downstream face slope increased to a maximum of 1:1.5, the ratio of the maximum distance from down-tracing point to downstream toe of the dam to the length of the dam along the flow direction (reflecting the final relative position of the down-tracing point) was correspondingly reduced to the minimum values of 0.24 and 0.18; When the relative scale of the dam reduced from 1 to 1/2, the value of x_p^*/x_d^* was correspondingly increased from 0.38 to 0.47. The dimensionless moving velocity of up-tracing point was constantly changing; There was a time delay of the peak breach water depth relative to the peak moving velocity, and the dimensionless delay time was about 0.04.

Key words: landslide dam, breach developing, depth erosion, tracing, overtopping