THREE-DIMENSIONAL ARBITRARY FRACTURE NETWORK SEEPAGE MODEL AND ITS SOLUTION

For the three-dimensional arbitrary fracture network seepage model,it is necessary to solve two key problems,i.e.how to get the seepage paths cutting by 3D arbitrary fracture networks,and how to analyze the seepage of two-dimensional arbitrary-shaped zone.All enclosed blocks cutting by arbitrary fractures can be searched by spatial block identification(3D block cutting) method.The boundaries of all blocks form the seepage paths.So the relationships of calculating nodes of seepage FEM can be determined by the connection relationships of the blocks' boundaries.On the other hand,block boundaries formed by fractures or openings are composed of closed loops with all kinds of shapes.The seepage occurring in the loops can be treated as 2D continuum seepage in the fracture's local coordinate system,and it can be solved by simplex integration even though the shapes of loops may be arbitrary.Then,according to the relationships of calculating nodes,the total seepage matrix and functions can be obtained;and the seepage calculation can be completed.At last,some cases are analyzed to check the theoretical schemes and calculating programs.The results of 3D fracture network seepage are applied to the block system for progressive failure analysis.