Scale parameters of soft structures for surrounding rock erosion prevention in rockburst-prone roadways

Practical experience in coal mines has suggested that establishing a loose and soft structure in the surrounding rock of roadways can play a role in wave attenuation, energy absorption and erosion prevention, which is conducive to the prevention of and reduction in the severity of rockburst disasters in coal mines. The scale parameters of soft structures includes two aspects: the size and the fracture degree of soft structures. The FLAC^3D numerical simulation software was used to study the failure characteristics of roadways with different impact positions (roof impact, side impact) and different impact energies (10⁴, 10⁵, 10⁶, and 10⁷ J). The stress reduction rates of soft structures with different sizes and fracture degrees were calculated. Based on the stress reduction rate of the soft structure, the energy absorption effect of the soft structure around the roadway was obtained as a logarithmic function of the soft structure size, which is a power function related to its fracture degree, and the intersection range of the two curves was fitted. The stress reduction rate was 30% when the soft structure size of the surrounding rock of the roadway was 10-15 m and the fracture degree was represented by 30-40% of the coal strength, which was the most reasonable range of scale parameters. The research conclusions provide a parametric basis for improving the theory and practice of rockburst prevention and support in coal mine roadways.