平面裂隙接触面积对裂隙渗透性的影响

Effects of Contact Area on the Permeability of Planar Fractures

岩体裂隙中往往存在充填物或因应力作用使裂隙局部区域闭合，因此，实际裂隙常存在接触区域而极少为完全张开型。接触区的存在必将影响裂隙的渗透性，本文运用数学模型对此问题进行了研究。文中的模型采用随机分布理论模拟接触面积的分布，并采用等参单元有限元技术对圆形、矩形两类裂隙中的水流进行计算和分析，得出了接触面积对裂隙渗透系数及流量影响的表达式。现有的室内试验数据验证了部分计算结果。计算表明，接触面积对裂隙渗透性影响放大，当接触面积达到裂隙总面积的３０％时，裂隙渗透系数减小为原来的５０％。

ontact area exists in real fractures because of the fracture fillings or the closing area of the fracture walls caused by loads.The existence of the contact area will affect the permeability of the fracture and this is investigated numerically in this paper.The random number theory is adopted to simulate the distribution manner of the contact arca and the isoparametric ele-ment technique is employed to analyse the flow in disc-shaped and square-shaped fractures.The indoor experiment data in literature proves the numerical results.The formulae obtaint-din this paper show that the pormeability decreases by 50 percent of its initial value when the contact arca occupies 30 percent of the total area of the fracture wall.