关键词: 城市地下水, 渗流, 悬挂式阻水结构, 阻力系数, 有限元

Abstract: For the large scale of regional seepage fields the horizontal 2D FEM is usually chosen as the analysis tool which assumes that the hydraulic head loss caused by vertical flow can be ignored. However, the hydraulic head loss around suspended structures is apparent. If the horizontal 2D FEM is used to model the suspended structures a major error will occur. In order to simulate suspended structures using the horizontal 2D FEM, a contact element is introduced. The contact element is used to consider the hydraulic head loss caused by vertical flow near suspended structures. The matrix equation of contact elements is deduced. The deduction is based on the coefficient resistance method and the analytical solution of flow near suspended cut-off walls under plane condition. The corresponding procedure is programmed. Two examples are studied. The result accuracy is assessed by comparison with 3D FEM. It is shown that they coincide each other on discharge; and that the hydraulic head gained by proposed method is the mean value of that computed by 3D FEM at the same location. The method presented is an effective way to simulate suspended cut-off structures in regional seepage fields.

Key words: urban groundwater, seepage, partially penetrated structure, resistance coefficient, finite elements