Abstract:

Studying the uplift failure of overlying strata in lined hard-rock underground chambers in metal mines for compressed air energy storage (CAES) holds important theoretical and practical significance for promoting the large-scale and commercial application of CAES technology. The non-linear Hoek-Brown failure criterion was used to investigate the uplift failure mechanism of the strata overlying underground chambers in metal mines under the high internal pressure of CAES based on expressions of the established geological strength index (GSI) and disturbed factor D for characterizing the velocities of sound waves and seismic waves. Additionally, the influence patterns of relevant factors on the uplift failure and ultimate internal pressure of the chambers were explored. The results show that the proposed analysis method for uplift failure of CAES chambers based on the Hoek-Brown criterion of wave velocities in rocks considers key factors and therefore is more comprehensive and reasonable than conventional methods. These factors include the overburden strength, rock mass structure, excavation and blasting-induced disturbance, and lateral pressure coefficient. As the uniaxial compressive strength of rocks σ_ci , the wave velocity in the undisturbed rock massC_p.ud , and wave velocity in the disturbed rock massC_p.d  increase, the uplift failure range of those strata overlying the chambers gradually increase and the required ultimate internal pressure P_u  increases accordingly. Meanwhile, the stability of CAES chambers is also enhanced. Due to excavation-induced unloading of ore bodies, the lateral pressure coefficient k of the surrounding rock changes, significantly affecting the uplift failure of those strata overlying the CAES chambers. As the lateral pressure coefficient k increases, the angle α  of fracture surfaces in overlying strata gradually decreases, and the rate of this decrease also exhibits a declining trend. The research provides a basis for the stability evaluation of rocks surrounding underground chambers in mines used for CAES and a design criterion to prevent uplift failure.

Key words: wave velocity in rock mass, Hoek-Brown failure criterion, compressed air energy storage(CAES), caverns in mines, uplift failure, ultimate internal pressure