TWO-DIMENSIONAL FRACTURED POROUS FLOW MODEL OF ARBITRARY FRACTURE NETWORK AND ITS TWO SOLUTION METHODS
ZHANG Qihua1，XU Wei2，YIN Jiaxia3
(1. Key Laboratory of Geotechnical Mechanics and Engineering of Ministry of Water Resources，Yangtze River Scientific Research Institute，Wuhan，Hubei 430010，China；2. HydroChina Chengdu Engineering Corporation，Chengdu，Sichuan 610072，
China；3. Southwest Electric Power Design Institute of China Power Engineering Consulting Group Corporation，
Chengdu，Sichuan 610021，China)
Abstract：In comparison with fracture network flow model，fractured porous flow model，which is also called as dual medium seepage model，assumes that the fractures and the blocks cut by fractures are all permeable. With this kind of model，only the determinate bigger fractures are considered in fracture network simulation，and the rock blocks and their inner stochastic small fractures can be treated as continuous porous media. So the fracture quantity can be decreased and the calculation capacity can be increased. Therefore，this kind of model has a significant development prospect in discontinuous rock mass fluid flow model. At first，the problems of fractured porous flow model are discussed. Then，two kinds of solution methods are summarized，which are called as global solution method and flow exchange method，respectively. In the global solution method，the fractures are considered as media with definite widths and modeled with solid elements. The conductivity matrices of fracture elements and block elements are incorporated to form the global conductivity matrix. The fracture solid elements are obtained by expanding fracture nodes in calculation codes，and needn?t to be generated in meshing. In the flow exchange method，the fluid flow of the fracture network system and the rock block system are calculated separately by forming conductivity matrices and flow functions respectively. Then，by means of flow exchanges between these two systems，the calculation results can be iterated with the balance of flow and the unique hydraulic head in one node. It is pointed out that the flow exchange influences only the flow balance function of the downstream node. At last，the characteristics of these two methods are contrasted by means of cases study. Additionally，arbitrarily shaped loop triangulation method without adding any node is put forward.
2012, Vol. 31 
