Grouting Simulation and Stability Analysis of Coal Mine Goaf Considering Hydromechanical Coupling

Accidents involving goaf collapse and ground subsidence can pose a huge potential hazard to both human health and the environment. Grouting for underground goaf is an important action commonly undertaken to reduce hydraulic conductivity and enhance stability. Due to the geological complexity and interdisciplinary nature of it, studying the stability of grouted goaf and overlying structure is an issue of crucial importance. Research on the goaf stability analysis simplified the grouted rock mass as a homogeneous material and ignored the coupled rock mass-fluid flow processes. For the grouting simulation, previous studies mainly focused on the grouting simulation in a single borehole or planar fractures and simulated the grouting process by a two-dimensional seepage model. Only a few of them have represented the actual operational conditions with dense boreholes and turbulent flow. In this study, a three-dimensional (3D) geoengineering model was developed based on the non uniform rational B-splines-triangulated irregular network-boundary representation (NURBS-TINBRep) hybrid data structure to represent complex geological structures. Then, considering the Bingham fluid characteristic, a 3D k-epsilon turbulence mathematical model was proposed so that the flow characteristics of grout and multihole grouting process in sequence were modeled. By applying the hydromechanical coupling theory, a 3D stability analysis model based on the geoengineering model was performed to analyze the effectiveness of grouting reinforcement and the stability of the goaf. (C) 2016 American Society of Civil Engineers.