岩体裂隙面形貌特征对其渗流特性的影响研究∗

岩体裂隙面的形貌特征直接影响其渗流特性,为了分析二者的相关关系,采用劈裂法制备了单裂隙砂岩试样,进行了裂隙面扫描分析和渗流试验,基于分形维数在定量表达不规则曲线形貌特征方面的优势,提出了考虑裂隙面形貌各向异性特征的分形维数计算方法。研究结果表明:(1)基于矩阵理论的裂隙面综合分形维数,相当于用矩阵网格去覆盖整个裂隙面,可以较好地反映裂隙面的整体形貌特征;(2)裂隙面的形貌特征对其渗流特性影响显著,随着裂隙面综合分形维数逐渐增大,裂隙岩体的渗透系数逐渐减小,而且侧向应力越大,渗透系数的减小趋势越明显;(3)分析建立了裂隙岩样渗透系数kf与裂隙面综合分形维数■的相关关系,验证分析表明,该公式计算得到的裂隙岩样渗透系数与试验结果吻合较好。相关研究成果可为裂隙岩体渗流特性分析提供参考。

Study on the Influence of Morphology of Rock Mass Fracture Surface on Its Seepage Characteristics

The morphology of the fracture surface of the rock mass directly affects the seepage characteristics,and a single fracture sandstone sample was prepared by the splitting test to analyze their correlation.The fracture surface scanning analysis and seepage test were carried out to quantitatively express the morphological characteristics of irregular curves based on fractal dimension,and the fractal dimension calculation method was proposed considering the anisotropic characteristics of fracture surface morphology.The results show that:(1) The comprehensive fractal dimension of the fracture surface based on matrix theory is equivalent to covering the whole fracture surface with matrix grid,which can better reflect the overall topography of the fracture surface;(2) The morphological characteristics of the fracture surface have a significant influence on the seepage characteristics.As the fractal dimension of the fracture surface increases,the permeability coefficient of the fractured rock decreases gradually,and with the increase of the lateral stress,the decreasing trend of the permeability coefficient becomes more obvious.(3) The correlation between the permeability coefficient kf of the fractured rock sample and the comprehensive fractal dimension ■ of the fracture surface can be expressed,and the verification analysis shows that permeability coefficient of the fractured rock calculated by the proposed empirical formula agrees well with the experimental results.The related research results can provide reference for the analysis of seepage characteristics of fractured rock mass.