Stress Characteristics and Rock Burst Prediction of the Xuefeng Mountain No.1 Tunnel: On-Site and Numerical Investigations

The risk level and disaster scale of rock bursts in deeply buried and highly stressed tunnels are commonly high, posing serious threats to their construction safety. This study employed a combination of on-site measurements and discrete-continuous coupled numerical simulations to analyze the geo-stress distribution characteristics of surrounding rock masses in the Xuefeng Mountain No.1 Tunnel. The evolution processes of rock burst failure in surrounding rock masses with different lithologies and buried at different depths were discussed. The risk of rock bursts along this long tunnel was predicted using the stress–strength ratio criterion and the energy method. The results showed that the principal stress values of surrounding rock masses in the Xuefeng Mountain No.1 Tunnel followed a distribution pattern of σx > σy > σz (where x, y, and z denoted the directions of tunnel cross-section and tunnel axis and the direction perpendicular to the ground), with average stress levels exceeding 20 MPa. It should be a typical tunnel dominated by horizontal tectonic stress. Stress concentration and elastic strain energy accumulation zones in this tunnel were mainly located at the bottom, and the largest displacements always occurred at the inverted arch. The main characteristics of rock burst failure in this tunnel included the sheet-like splitting of rock mass layers and the ejection of rock blocks. The risk evaluation of rock bursts across different sections of the tunnel, considering various rock types and buried depths, presented that these deeply buried slate and granite exhibited the highest risk level when assessed using the elastic strain energy index criterion. The comparative analysis between the elastic strain energy method and the stress–strength ratio criterion showed that the evaluation results obtained by the latter were more conservative. The findings of this study can provide a valuable reference for cognizing the geo-stress characteristics and predicting rock bursts in the surrounding rock masses of deep-buried and highly stressed tunnels.