中文摘要：

本文基于颗粒流理论，运用PFC^2D计算程序的FISHTANK函数库和FISH语言，定义了细观角度概念——流体域。并分别定义了流体域的流动方程和压力方程。将颗粒体与流体域耦合。推导出颗粒流理论显式求解的稳定条件，成功地对土中的渗流进行了模拟。得到了渗流过程中压力和流速的变化规律。结果表明，运用PFC^2D程序模拟的渗流规律符合达西定律，这一结果为PFC^2D在渗流和渗透破坏等方面的深入研究应用提供了一定的理论基础。

英文摘要：

By using the function library and FISH language of software PFC^2D, the domain of flow is defined from the viewpoint of meso-mechanics and the formulas for flow and pressure are established respectively on the basis of particle flow code theory. The particles flow are coupled with flow domain to deduce the critical condition for stability in explicit solution scheme. By this method the seepage flow in soil can be simulated and the variations of pressure and velocity in the flow passage are obtained, The study result shows that the seepage flow simulated by PFC^2D obeys the Darcy＇s law.