Numerical Study on the Mechanism of Rockburst Prevention Using Artificial Fracture Method Based on Strain Energy Theory

The artificial fracture method to prevent rockburst is mostly based on experience, and it is often difficult to achieve the ideal effect of weakening the surrounding rock. The main reason is lacking of understanding of its prevention mechanism and theoretical guidance. Therefore, this paper takes a local rock mass with an artificial fracture on the tunnel wall as the research object, and the three-dimensional discrete element method was used to establish a simplified numerical model. Then the mechanism of artificial fractures to prevent rockburst was studied from the perspective of strain energy evolution theory, and its key influencing factors were discussed. The results show that: its prevention mechanism is firstly to limit the total strain energy of the rock mass through artificial fracture, which reduced the energy source; and increase the proportion of dissipated energy before structural failure, which induces more damage but reduces the storage limitation and post-peak release velocity of elastic strain energy. Eventually changes the local rock on the tunnel wall from sudden failure to gradual failure. But, the prevention effect is controlled by the width and the dip angle of the fracture. To reach the best effect, the artificial fracture should have a certain width and intersect with the maximum circumferential stress at a medium angle (around 45°). The research results are helpful to reveal the essential reasons for the unsatisfactory prevention effect in engineering practices, and provide a theoretical reference for design of the artificial fracture.