Study On Seepage Characteristics Of Broken Rock Mass Under Erosion

Water outburst caused by geological structures such as Karst collapse columns and faults become one of the most heavy disasters and threaten the safty mining as coal mining developto the deep underground.In recent years,some researchers began to study the geological structure outburst from the aspect of solid-fluid system instability for broken rock.However,the problem of broken rock seepage instability caused by mass loss due to mass loss have not attracted enough attention.This project carry out systematically experimental and basic theoretical study on the coupling interaction of solid particle migration,fluid transport and broken rock deformation during the seepage of broken rock.The main research content including:(1)we considered the effect of filling material on the seepage characteristics of broken rock mass,and carried out the seepage testing for broken rock mass under the effect of particles transport by using the self-designed experiment system,analyzed the evolution of broken rock mass permeability under the effect of mass loss,and the study results indicated that the seepage characteristics of broken rock mass can be classified into three stages,i.e.the seepage slowing stage,rapid increase stage and seepage stability stage.(2)Based on the dual-porosity model,a fully coupled model for Karst Collapse Pillars(KCPs)water inrush was developed by incorporating the fractures and porosity evolution for KCPs,particles migration,and water seepage process.(3)The governing equation was implemented into COMSOL Multiphysics software.The heterogeneity of rocks in KCPs was determined using the parameters including porosity,seepage,particle concentration,water inflow as well as seepage channels evolution law was obtained accordingly.This numerical model was then used to investigate the water flow characteristics with erosion.The general approach developed in this work can be used to investigate the evolution of rock fracture networks for different rock properties and to offer a way that has been approved to be effective to predict water inrush time to avoid catastrophic consequences caused by broken geological structures such as faults and KCPs.This paper reveals the mechanism of water bursting caused by the geological structure such as the collapse column,and provides guidance and reference for its water inrush prevention and control from the perspective of the instability of the fluid-solid coupling system caused by the change of the permeability of the broken rock.