不同粗糙裂隙表面几何特性与渗流研究

Study on Geometric Characteristics and Seepage of Rock Fracture Surfaces with Different Roughness

为研究裂隙形貌特征及对渗流特性的影响,采用四目高精度三维扫描仪,测量劈裂破坏后的岩石裂隙三维形貌,通过Geomagic Studio软件选取基准面进行点云处理,基于地理信息技术(GIS)获取裂隙表面形貌参数,导入Comsol数值分析软件,分析了恒定水头下,裂隙粗糙度对水头变化、流速和水力传导率的影响。结果表明:(1)裂隙面粗糙高度基本符合正态分布,随着粗糙度系数J_(JRC)的增大,裂隙面粗糙高度频率分布直方图由标准型逐渐演变为陡壁型、偏峰型、锯齿型,坡向分布趋于集中,平均坡度逐渐增大;(2)流体在裂隙内流动存在绕流现象,并且粗糙度不同的区域流速大小存在显著差异,粗糙度系数J_(JRC)大的区域水头减小速率较慢;(3)流速和水力传导率(K_(s))与J_(JRC)呈指数函数关系,水力传导率随着裂隙面粗糙度系数J_(JRC)的增大而减小,减小趋势在J_(JRC)大于10以后而逐渐变缓。

In order to study the characteristics of fracture morphology and its influence on seepage characteristics,the three-dimensional morphology of rock fracture after splitting failure was measured by four-eye high-precision three-dimensional scanner.Through Geomagic Studio software,the datum plane was selected for point cloud processing.Based on geographic information technology(GIS),the fracture surface topography parameters were obtained and imported into Comsol numerical analysis software to analyze the influence of fracture roughness on head change,flow velocity and hydraulic conductivity under constant head.The results are drawn as follows.Firstly,the roughness height of fracture surface basically conforms to normal distribution.With the increase of the roughness coefficient J_(JRC),the frequency distribution histogram of the roughness height of the fracture surface gradually evolves from the standard type to the steep wall type,the peak type and the sawtooth type.The slope direction distribution tends to be concentrated,and the average slope gradually increases.Secondly,there is a phenomenon of flow around the fluid in the fracture,and the velocity is significantly different in the areas with different roughness.The decrease rate of the water head in the area with large roughness coefficient J_(JRC) is slow.Thirdly,the flow velocity and hydraulic conductivity(Ks)have an exponential function relationship with J_(JRC).The hydraulic conductivity decreases with the increase of fracture surface roughness coefficient J_(JRC),and the decreasing trend gradually slows down after J_(JRC) is greater than 10.