Early estimation method of rockburst and large deformation of surrounding rock based on the deep borehole test

Abstract

In geotechnical engineering, several major catastrophic accidents occur frequently in areas of high in-situ stress. To study the influence of high in-situ stress on deep mining, the in-situ stress was tested using the hydraulic fracturing method in the mine. Based on the measured data of the initial stress, a comprehensive evaluation of the stress field of the deep surrounding rocks was carried out. Combining the physical and mechanical indexes of the surrounding rocks, field measurements, and theoretical analysis, the Russenes criterion and Turchaninov criterion were applied to evaluate the propensity of rockbursts of hard rocks in the mine area. In addition, the large deformation of the soft rock in the mine was predicted based on the large deformation classification criteria. The results demonstrate that the vertical stress is linearly related to the depth. The horizontal principal stress values tested in all holes except boreholes G and I are approximately linearly distributed with depth. The greater the depth, the greater the propensity for rockburst. For obvious deviation from the maximum horizontal main stress direction of the mining tunnel, the tendency of rockburst during construction is greater. Slight deformation occurs when the tunnel surrounding rock is shallow than 660 m; larger deformation occurs when the burial depth exceeds 660 m. Level-Ⅱ or level-Ⅲ deformations may occur near the bottom of holes F, G, and I due to the lower uniaxial compressive strength of the phyllites of these holes.