岩溶隧道开挖过程中突水发生机制复杂,本文以Darcy定律、Brinkman方程及Navier-Stokes(N-S)等渗流方程为基础,应用多场耦合数值分析工具,在计算模型中耦合Darcy流、Brinkman和N-S等不同的渗流控制方程,将深部含水层、隧道开挖破碎带和隧道临空面整个突水水流路径相连接,实现突水流动的全过程模拟。明月山隧道突水算例表明,在开挖扰动作用下,地下水沿节理裂隙流动导致隧道突水;单一裂隙水流速和水压较大,而多管道溶隙具有分流分压作用;隧道与断层呈小角度相交时流速较小,断层能起到截水的作用,而呈大角度相交时,断层不仅有导水的作用,更加剧了突水的流通。
The mechanism of water burst in karst tunnel excavation is complex.Based on Darcy's law,Brinkman equation and Navier-Stokes(N-S) equations,multi-coupling software is used to simulate water burst process in this paper.Deep aquifer can be expressed using Darcy's law,the broken zone of excavation is expressed using Brinkman equation and free face of the tunnel is expressed using N-S equations in a karst tunnel.Taken the Mingyueshan tunnel as an example,the results show that single fracture flow is small,but the whole complex cross rock fracture is likely to cause water pressure to concentrate.Through the external disturbance,groundwater may flows along the cracks and eventually leads to water burst in a tunnel.The velocity of flow is slow if the fault obtains even small angle with the tunnel,because the fault can play the role in water cut.While with the wide-angle intersection,the fault is not only the role of hydraulic conductivity,but also exacerbates the flow channel.