Abstract:

One of the main causes of urban ground subsidence is groundwater seepage. Finite element method is not an ideal method to reveal the microscopic mechanism of ground settlement. With discrete element method, the microscopic mechanism may be revealed, but it doesn't help with the building of a flow filed model with complex shape. Based on discrete element method (DEM) and computational fluid dynamics (CFD) coupling principle, a fluid-solid coupling method is proposed. This method uses PFC to simulate the solid phase and Fluent to simulate the liquid phase. It achieves fluid-solid coupling calculation based on particle microscopic view. Then this method is applied to the study of ground settlement caused by seepage. The effectiveness and feasibility of this method are verified by three examples. It is found that the PFC-Fluent method can show the whole dynamic process of ground settlement caused by seepage from a microscopic perspective, and can also realize the simulation and calculation of various complex shape conditions. The stability of soil was changed under the influence of seepage, and the soil migration lead to ground subsidence. Land subsidence increases with the rise of hydraulic gradient. This study reveals the whole process of ground subsidence under the action of hydraulic gradient, which provides a basis for the prevention and control of urban geological hazards.

Key words: fluid-solid coupling, groundwater seepage, ground subsidence, seepage of foundation pit face, seepage of river channel