不饱和十字交叉型裂隙流动的尺寸效应

The size effect of the unsaturated cross intersection fracture flow

随着煤矿开采深度的增加,矿井突水问题更加突出。由于岩体裂隙空间几何形态的复杂性,使得目前在研究裂隙岩体渗流特性方面还存在诸多困难,尤其关于十字交叉型裂隙的流体流动规律方面的研究较少。本文用Fluent对9种不同尺寸的十字交叉型裂隙进行二维渗流数值分析,从裂隙流体的压强场、速度场、水分布场、流体流量特征4个方面分析裂隙的尺寸效应。结果表明:纵向裂隙范围内的流体速度及压强相比于横向裂隙要大得多,且同一点处的速度和压强值随时间的变化趋势基本一致。当纵向裂隙宽度在0.1~0.3 mm之间时,存在一个临界值使得表面张力等于水的自重与气体施加的大气压力之和;横向裂隙宽度在0.3~0.5 mm之间时,存在一个临界值使得表面张力等于气体施加的大气压力。

The problem of water inrush is more prominent in deep coal mining. Due to complexity of geometry for rock mass fractures,there are still many difficulties in studying the seepage characteristics,especially,the rule of fluid flow in the cross fracture are less reported. In this paper,the seepage of cross fracture,with nine different sizes,was studied by using two-dimensional numerical analysis software Fluent. The size effects of fractures were analyzed from four aspects: pressure field,velocity field,water distribution field and fluid flow characteristics. The results show that the velocity and pressure in the range of longitudinal fracture are much larger than those in transverse fracture. The tendency of velocity with time is consistent with that of pressure at the same point. There is a critical value of longitudinal fracture between 0.1 mm and 0.3 mm that the surface tension is equal to the sum of the weight of the water and atmospheric pressure imposed by gas; and there is another critical value of transverse fracture between 0.3 mm and 0.5 mm that the surface tension equals the applied force of gas.