渗流分析中排水孔模拟的叠单元法

排水孔是重要的渗控措施,如何准确模拟排水孔的作用是渗流分析中的关键问题之一。目前普遍采用排水子结构法,但由于子结构网格依存于整体网格,在解决复杂工程问题时网格划分难度很大。文中提出一种新的排水孔模拟方法——叠单元法。对于含排水孔的结构,将其划分为不包含排水孔的整体网格以及各排水孔附近区域的局部网格,网格之间相互独立。然后,通过排水孔局部网格的外边界面的虚拟渗流,实现整体网格与排水孔局部网格的耦合。算例分析的结果表明,当排水孔局部网格范围大小取为整体网格单元尺寸的1～3倍,外边界面渗透系数取为材料渗透系数的102～103倍时,所提方法能够准确模拟排水孔的作用。由于叠单元法的网格划分简便易行,有望广泛应用于复杂工程问题的渗流分析。

Superposed element method for simulating of drainage holes in seepage analysis

The drainage hole is an important seepage control measure, so it is one of the key problems to simulate the effect of the drainage hole in the seepage analysis. Although the substructure method is an effective and popularized method, its mesh generation, which is dependent on the global mesh, is still a difficult task in engineering practice. A novel method named superposed element method (SEM) is proposed to simulate the drainage holes. Firstly, the structure containing drainage holes is divided into two independent meshes. One is the global mesh without drainage holes, and the other is the local mesh of the drainage hole together with its adjacent zone. Then, the two independent meshes are coupled together through the virtual seepage on the outer interface of the local mesh. Finally, two numerical examples are studied, in which the effect of the drainage holes can be simulated accurately. According to the results of the sensitive analysis, the proper range of the local mesh is 1–3 times of the element length in the global mesh; and the permeability coefficient of the outer interface is suggested to be 102–103 times of the material permeability coefficient. Since the mesh generation of the superposed element method is quite simple, the new method is expected to be widely used to solve complicated seepage problems in engineering practice