裂隙岩体渗透性影响因素的研究

采用UDEC离散单元法中关于裂隙岩体开挖模拟及水力全耦合分析模型,分析裂隙岩体洞室开挖后,因围岩应力与水力耦合作用导致裂隙隙宽变化及渗流变化的过程。为了更直观地了解耦合作用对裂隙岩体渗透特性的影响,以隧洞开挖为例,用开挖后隧洞内总涌水量来表征岩体的渗透特性。利用数值试验的方法,研究了块体边界大小、初始应力比、裂隙隙宽和裂隙夹角对开挖后隧洞内涌水量变化的影响,进而可以看出它们对裂隙岩体渗透性的影响。并得出如下结论：随着块体尺寸和初始应力比的增大,隧洞内总涌水量减少;随初始隙宽的增大涌水量增加并当达到某一固定值时保持不变;隧洞涌水量在θ2/θ1=3.5,其中θ1=30°,即两组节理的夹角为75°处达到最大。

Study on the Factors Affecting the Permeability of Fractured Rocks

The excavation simulation and fully-coupled model of the fractured rock in the discrete element method are used to analyze the changes in fracture aperture and in the seepage flow process after excavation.The flowing discharge after tunnel excavation is used to represent the permeability of the fractured rock mass in the article,in order to investigate the coupling effect on the permeability characteristics of the fractured rock mass.The effect on flowing discharge in the excavated cavity or tunnel by block boundary size,initial in-situ stress ratio,the fracture aperture and the included angle were studied based on the numerical test.It is found that with the increase of block size and the in-situ stress ratio,the flowing discharge in the excavated tunnel becomes decreasing;and with the increase of initial hydraulic aperture,the flowing discharge increases coincidently and keeps invariant with a fixed amount.The flowing discharge reaches the maximum value when the included angle between the two joint sets is 75.