Prediction of rockburst tendency of horizontal layered hard rock tunnel in high ground stress environment: A case study

Rockburst is a critical dynamic hazard in deep high-stress hard rock tunnels. The Daxiagu Tunnel in southwestern China, crossing extensive horizontally layered dolomite under ultra-high stress, suffers frequent rockbursts poorly predicted by traditional methods, as most existing energy criteria are derived from intact rock without bedding weakening correction. This study develops a modified rockburst energy criterion via triaxial unloading tests, numerical simulation and field validation. Under 40 MPa confining pressure, dolomite energy storage limits drop to 52%, 42% and 30% of intact rock for 1 horizontal, 1 vertical and 4 horizontal bedding sets, respectively. Numerical simulation shows that vault principal stress doubles the initial value, with peak elastic strain energy of 233.5 kJ/m³ and 9 m excavation disturbance range. Field validation confirms that the modified criterion outperforms traditional strength-stress ratio criteria and matches actual records well, providing a reliable prediction method for similar projects.