Composite element method for the seepage analysis of rock masses containing fractures and drainage holes

The composite element method (CEM) is formulated for the seepage analysis of rock masses containing fractures and drainage holes. Each fracture or drainage segment is treated as a special sub-element having definite seepage characteristics, and is located explicitly within the composite element. The governing equation for the composite element containing both fractures and drainage holes is established using the variational principle. By the CEM developed in this paper, the fractures and drainage holes can be simulated explicitly but do not intervene in the discrete of the calculation domain concerned, in this way the generation of the computation mesh is not restricted strongly by the position and the orientation of the fractures and drainage holes, which is important in the optimal design of seepage control system. If there are no fractures and drainage holes, the CEM will automatically be degenerated to the conventional finite element method (FEM). The validity and reliability of the CEM is verified by a numerical example. The application and comparative study for the Baozhusi dam foundation is presented.