岩体裂隙连通路径及岩体等效渗透张量参数研究

Study on Connected Path of Rock Fracture and Equivalent Permeability Tensor Parameters of Rock Mass

在高放核废料的处置中,掌握地下水在裂隙岩体中的渗流规律是当下的关键问题。以甘肃北山岌岌槽一测区为工程背景,通过现场数据测得的裂隙统计参数,应用编制的MATLAB语言程序生成全局域内的离散裂隙网络模型,将三维裂隙以圆盘模拟并简化为变截面圆管单元渗流网络,为考虑边缘效应以圆管作为单元体切割基准。通过比较随单元体尺寸增大的三个方向上的等效渗透系数变化趋势得到表征单元体REV,并在该单元体中计算渗透张量以及应用Dijkstra算法识别对应边界方向的最优路径。结果表明:该测区的渗透系数最值分别为3.62e-6m/s与9.19e-7m/s,水平向渗透性最小,竖直向附近最大,基本符合工程实际。

In the disposal of high-level nuclear waste,mastering the seepage law of groundwater in fractured rock mass is a key issue at present. With the engineering background of a surveying area in Gansu Beishan,the discrete fracture network model in the global domain was generated using the MATLAB code based on the statistical parameters of fracture properties measured by field data. The three-dimensional disc-shaped fractures are modeled and simplified as channel element network with variable cross-sections,and each channel element is cut in the research cube for the consideration of the edge effect. Then the Representative Element Volume(REV)is characterized by comparing the trend of the equivalent permeability coefficient in three directions which changes as the size of research cube is getting larger;the permeability tensor is calculated and the optimum path of the corresponding boundary direction is recognized by use of the improved Dijkstra algorithm in this REV cell. The results show that the maximum and minimum values of the permeability coefficient of the measured area are 3.62 e-6 m/s and 9.19 e-7 m/s,respectively,which has the lowest permeability in horizontal plane and the highest one around the vertical direction,and this results are basically in line with the actual project. All these programming ideas and simulation results can provide a reference for solving related engineering problems.