水工混凝土结构常带缝运行于水压与渗流共同作用的复杂工况下，在处理其结构渗流场与位移场耦合问题时，为了避免经典有限元法确定两场间变量对应关系的麻烦和不同网格分析的协调问题，将扩展有限元引入水工裂缝结构稳定渗流场的分析中，通过研究渗流场分析中裂缝单元水头的节点加强方式，构造出能使裂缝位置处渗透压力连续并反映裂缝内传导系数矩阵特点的节点加强函数，从而得出渗流场的扩展有限元逼近形式，建立扩展有限元法求解渗流场的离散方程和求解步骤，将渗流场和位移场统一在扩展有限元框架下求解。实例分析表明，裂缝的存在对裂缝区渗流场的影响较大，裂缝内水流渗透坡降较小，与实际情况相符，验证了该方法求解渗流场的可行性和所编程序的正确性。%Hydraulic concrete structures often run under the complex coupling conditions of water pressure and seepage action with seams. In order to avoid the problems of determining correspondence of variables and the coordination problems of grids in dealing with the coupling problem between seepage and displacement fields by using the FEM. The XFEM was introduced into the analysis of the seepage field in hydraulic structures in this paper. Firstly, it analyzed the enriched forms of nodes in elements intersecting with cracks, and then built the enriched functions, which could either reflect the features of conductivity matrix within cracks, or satisfy the conditions of that osmotic pressure was continuous across the crack. Thus obtained the XFEM approximation form,combining with the initial conditions and boundary conditions, the discrete equations and workflow of XFEM for solving the seepage field was established. Thus, the seepage and displacement field could be unified under the framework of XFEM. Case study shows that the impact of cracks on the seepage field within crack area is significant, and the osmotic gradient decreased, which is in line with the actual situation. The presented method is reasonable and reliable.
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