Abstract: The slot-cut method is put forward, aiming at the problem of frequent rockburst for hydropower projects in Southwest China. The mechanism and method of slot-cut prevention of delayed rockburst are discussed by theoretical analysis, numerical simulation, and construction technology. The existence of slots provides extra space for circumferential deformation, thus decreases the circumferential stress on the surface of surrounding rock mass. The plastic strain formed on the slot bottom and between slots absorbs part of the elastic strain energy stored in the rock mass. It’s revealed by the numerical analysis that the location, spacing and number of slots should be arranged reasonably for better prevention effect. In actual practice, the slots-cutting operation should be well designed, for more accurate control on the dimensions of slots, and can be accomplished by drill-blasting or accumulative explosives pre-split blasting.

Key words: rockburst, in-situ stress, slot-cut, cumulative presplit