A 3D microseismic data-driven damage model for jointed rock mass under hydro-mechanical coupling conditions and its application

Abstract

Rock mass is a fractured porous medium usually subjected to complex geostress and fluid pressure simultaneously. Moreover, the properties of rock mass change in time and space due to mining-induced fractures. Therefore, it is always challenging to accurately measure rock mass properties. In this study, a three-dimensional (3D) microseismic (MS) data-driven damage model for jointed rock mass under hydro-mechanical coupling conditions is proposed. It is a 3D finite element model that takes seepage, damage and stress field effects into account jointly. Multiple factors (i.e. joints, water and microseismicity) are used to optimize the rock mass mechanical parameters at different scales. The model is applied in Shirengou iron mine to study the damage evolution of rock mass and assess the crown pillar stability during the transition from open-pit to underground mining. It is found that the damage pattern is mostly controlled by the structure, water and rock mass parameters. The damage pattern is evidently different from the two-dimensional result and is more consistent with the field observations. This difference is caused by the MS-derived damage acting on the rock mass. MS data are responsible for gradually correcting the damage zone, changing the direction in which it expands, and promoting it to evolve close to reality. For the crown pillar, the proposed model yields a more trustworthy safety factor. In order to guarantee the stability of the pillar, it is suggested to take waterproof and reinforcement measures in areas with a high degree of damage.

Keywords

• Microseismic monitoring
• Numerical simulation
• Rock damage
• Jointed rock mass
• Hydro-mechanical coupling