矿井岩体破坏突水机制及非线性渗流模型初探

WATER INRUSH MECHANISM IN MINES AND NONLINEAR FLOW MODEL FOR FRACTURED ROCKS

矿山采动围岩破坏突水过程中,水流经历了在含水层中的Darcy层流、破碎带中的非Darcy快速流以及进入巷道中的Navier-Stokes紊流3个物理过程。研究表明Brinkman方程比较适合破碎带渗流特点;同时,将含水层Darcy渗流和巷道N-S流动有机联系在统一流动场中,基于质量守恒和压力平衡,建立突水流体流动数值模型。据此,以采动诱发陷落柱突水为例,应用COMSOL Multiphysics系统数值分析工具,通过在模型中耦合Brinkman,Navier-Stokes和Darcy方程,把含水层、岩体破碎带和巷道整个突水水流路径连接在一起,模拟突水流动全过程。计算结果表明,陷落柱作为含水层渗流和巷道突水自由流动的过渡区域,其渗透性变化对于突水压力和流速演变十分敏感,陷落柱或导水破碎带沟通了含水层和巷道之间的水力联系,而含水层充足的补给水量是保持恒定的高水压并沿陷落柱形成突水的根源。

The water inrush in mines may experience three processes including Darcy flow in a confined aquifer,non-Darcy flow in fractured zone in fault and Navier-Stokes′ turbulent flow in tunnel.A water-inrush model,in which the Brinkman equation is thought to be suitable for describing the fluid flow in the fractured zone in fault,and also the Darcy equation and the Navier-Stokes′s equation are receptively used to characterize the flow in confined aquifer and in tunneli,s proposed based on conservation of mass and pressure balancei,n order to predict the hydraulic processes during the water inrush.This model is considered to be promising and practical for characterizing the whole fluid flow and water-inrush processes.Then,as a typical example,the water-inrush due to karstic collapse columns,which is considered to be a coupled processes that can be characterized with Darcy equation in confined aquifer,Brinkman equation in fractured zone and Navier-Stokes′s equation in tunnel,is simulated when the above-proposed model is implemented into COMSOL Multiphysics.The complete fluid flow process in confined aquifer,fractured zone and tunnel are all numerically predicted.The numerical results indicate that,the karstic collapse column,being a fractured zone in rock mass,is the transition zone between linear Darcy flow in confined acquirer and water-inrush in tunnel,and its permeability is very sensitive to the water pressure and the flow velocity.The karstic collapse column or fractured zone is the channel that connects the confined aquifer and tunnel,and the recharge of confined aquifer is the main cause that leads to the high water pressure and the water inrush through the karstic collapse columns.