摘要
裂隙岩体渗流具有非均匀性和各向异性,其复杂性体现在单裂隙的密度、产状和迹长等参数上以及裂隙网络的连通性上,而裂隙网络的连通性是三维裂隙岩体渗流参数计算的一个难题。目前三维裂隙岩体渗流参数的计算方法因其模型假设的不同而各有优缺点。为分析裂隙岩体水力各向异性及其渗透系数,基于降维思路,提出了三维裂隙岩体密集切面求解渗透系数的新方法。该方法在三维裂隙网络模拟的基础上,通过不同方向密集切面逼近裂隙岩体,将三维裂隙网络分解成多个连续的二维切面裂隙网络,对切面裂隙网络使用图论法分析裂隙水力的连通性和渗透路径,设置水头边界条件计算渗透系数,通过空间上线、面、体的关系,将二维空间上的渗透系数计算结果表达三维空间上的方向性,构建三维裂隙岩体网络的渗透张量。将切面渗透系数视为渗透椭圆计算切面渗透系数,给出了一种新的岩体渗透张量的求解公式。同时讨论了尺度效应和裂隙岩体渗透各向异性的表征方式,通过构建三维和二维裂隙网络,截取不同大小的单元体计算渗透系数,得出典型单元体的边长为20 m,并通过野外现场钻孔压水实验验证了方法的可行性。研究成果可以为求解不同尺度、非均质裂隙岩体各方向渗透系数提供参考。
[Objective]The seepage in fractured rock masses is non-uniform and anisotropic,with its complexity reflected in the density,orientation,and trace length of individual fractures,as well as the connectivity of fracture networks.The connectivity of fracture networks poses a significant challenge in calculating the seepage parameters of three-dimensional(3D)fractured rock masses.Currently,methods for calculating seepage parameters of 3D fractured rock masses have their own advantages and disadvantages,depending on the model assumptions they used.To analyse the hydraulic anisotropy and permeability coefficients of fractured rock masses,a new method for solving the permeability coefficient of a 3D fractured rock mass based on dense sections is proposed using the dimensionality reduction.[Methods]This method involves simulating 3D fracture networks and approximating fractured rock masses using dense sections in different directions.The 3D fracture network is decomposed into multiple continuous two-dimensional(2D)sectional fracture networks,and the graph theory is applied to analysing the hydraulic connectivity and permeability paths.Water head boundary conditions are then set to calculate the permeability coefficient.By leveraging the geometric relationships among lines,surfaces,and volumes in 3D space,the calculated permeability coefficient is expressed as the directional permeability in 3D space,and a permeability tensor for the 3D fractured rock mass is constructed.[Results]By treating the section permeability coefficient as a permeability ellipse,the new method calculates the equivalent permeability coefficient of the section and provides a formula for the equivalent permeability tensor of the rock mass.The scale effect and representation of anisotropy in the rock mass are also discussed.The 3D and 2D fracture networks are constructed,and different sizes of unit cells are intercepted to calculate the permeability coefficient,with a typical unit size determined to be 20 m.The method's feasibility is verified through field water pressure experiments.[Conclusion]This method provides a important reference for solving the permeability coefficients in different directions of heterogeneous fractured rock masses at various scales.
作者
韦娟华
付豪
唐朝晖
张腾飞
柴波
WEI Juanhua;FU Hao;TANG Zhaohui;ZHANG Tengfei;CHAI Bo(Institute of Geological Survey,China University of Geosciences(Wuhan),Wuhan 430074,China;School of Environmental Studies,China University of Geosciences(Wuhan),Wuhan 430074,China;Faculty of Engineering,China University of Geosciences(Wuhan),Wuhan 430074,China;Changqing Oilfield Technical Monitoring Center,Xi'an 710018,China)
出处
《地质科技通报》
北大核心
2025年第5期191-201,共11页
Bulletin of Geological Science and Technology
基金
国家自然科学基金项目(42172318,42177159)。
关键词
三维裂隙网络
降维
多切面
渗透系数
裂隙岩体
three-dimensional(3D)fracture network
dimension ality reduction
multi section
permeability coefficient
fractured rock mass
