不同围压下粗糙裂隙渗流规律试验研究

Experimental Study on Seepage Law of Rough Fractures Under Different Confining Pressures

了解应力耦合条件下裂隙岩体中的流体流动特性对于指导岩土工程设计具有重要意义。为了研究粗糙度和围压对裂隙岩体渗流的影响,首先通过三维形貌扫描仪获得了预制裂隙面的形貌数据;之后在围压为1.0~5.0 MPa的条件下,对不同粗糙度的砂岩裂隙试样开展了不匹配渗流试验。试验研究结果表明:在围压恒定时,不匹配砂岩裂隙中流量均随着压力梯度的增加而增大,而且,福希海默方程可以很好地描述压力梯度和流量之间的非线性关系。围压和压力梯度不变时,岩石裂隙中的流量随粗糙度的增加而减小。进一步研究发现,福希海默方程中的线性系数a和非线性系数b均随着表面粗糙度和围压的增加而增大。表观导水系数并非恒定不变的常数,其数值随着雷诺数的增大而减小,水力开度e随着围压的增大而减小。

Understanding the fluid flow characteristics in fractured rock mass under stress coupling conditions is of great significance for guiding geotechnical engineering design.In order to study the influences of roughness and confining pressure on the seepage of fractured rock mass,the morphology data of prefabricated fracture surfaces were obtained by three-dimensional topography scanner.Then,under the confining pressure of 1.0-5.0 MPa,the mismatched seepage tests were carried out on sandstone samples with different roughness.The experimental results show that when the confining pressure is constant,the flow rate in the mismatched sandstone fracture increases with the increase of pressure gradient,and the Fuchsheimer equation can well describe the nonlinear relationship between pressure gradient and flow rate.When the confining pressure and pressure gradient are constant,the flow rate in the rock fracture decreases with the increase of roughness.Further research shows that both the linear coefficient a and nonlinear coefficient b in the Fuchsheimer equation increase with the increase of surface roughness and confining pressure.The apparent hydraulic conductivity is not a constant,but decreases with the increase of Reynolds number,and the hydraulic aperture eh decreases with the increase of confining pressure.