前伏溶洞巷道开挖突水数值模拟研究

Numerical Simulation of Water Burst in Roadway Excavation with Karst Cave Ahead

为研究前伏溶洞对巷道开挖围岩稳定性的影响,文章结合工程实例,采用FLAC^3D建立考虑渗流-应力-损伤相互影响的数值模型,分析了溶洞巷道围岩在开挖过程中应力、变形、塑性区以及渗流场的变化特征。分析结果表明:(1)当工作面靠近溶洞时,溶洞对巷道前方岩体的分区破裂损伤现象有一定的抑制作用;(2)随着工作面距溶洞距离的减小,巷道工作面岩体最大位移将逐渐增大并出现"突变"特征,同时最大位移位置也会随着涌水通道的变化而不断变化;(3)当防水岩柱小于一定厚度时,前伏溶洞巷道围岩涌水量将会突然增大,表现出明显的突水现象;(4)巷道围岩渗流与渗透系数变化是导致前伏溶洞巷道突然发生坍塌、掉块以及突水的根本原因。

In order to research the influence of karst cave ahead of roadway on surrounding rock stability,a numeri⁃cal model is established by FLAC^3D considering the interaction of seepage,stress and damage,the variation charac⁃teristics of stress,deformation,plastic zone and seepage field of surrounding rocks during excavation are analyzed.The numerical results show that:(1)when working face is close to krast cave,the karst cave has certain effect of inhi⁃bition to the zonal disintegration of surrounding rock ahead of roadway;(2)with the decrease of distance from karst cave,the maximum displacement of rock mass will gradually increase and present"abrupt change"characteristics,while the position of maximum displacement will change with the variation of water inflow channel;(3)when waterproof pillar is less than a certain thickness,the water inflow of surrounding rocks will suddenly increase and show obvious water burst;(4)seepageand variation of permeability coefficient of surrounding rocks are the basic reasons to cause collapse,chip off-falling and water inflow.