路基边坡冲刷特性的颗粒流模拟

Simulation Research on Characteristics of Embankment Slope under Rainfall Scour

利用离散元软件PFC^(2D)(Particle Flow Code)模拟边坡冲刷的特点,考虑坡度、径流流速、粒径、粘土c值、砂土摩擦角φ值等影响因素,模拟粘土和砂土两种边坡。粘土边坡模型的建立采用BPM(Bonded Particle Model)模型,即通过在颗粒之间设置粘聚力,将不同的颗粒粘结在一起。主要研究基于PFC^(2D)的边坡冲刷特性,得出边坡冲刷破坏的形态规律,并通过设定冲刷准则以考虑临界冲刷速度,通过Fish语言编程记录颗粒的位移大小。由模拟得出粘土路基边坡由于颗粒之间的粘结作用会呈现团粒、块状冲起或片状剥落;砂土边坡呈现出平行于边坡表面的颗粒层状冲刷剥落,即形成冲刷沟。并得出临界冲刷速度与粒径、坡度等的大致关系,并与实际的物理模型实验结果进行对比,结果一致,可为路基边坡的防护措施提供参考意见。

Using PFC^2D（Particle Flow Code） to simulate the response of embankment slop under rainfall action in order to reveal the characteristics of embankment in that condition. During the simulation research we take kinds of variable into consideration such as slope angle,friction angle,diameter of particle,flow velocity et al. Two kinds of slope were simulated,one is sand slope and the other is clay slope. The clay slope was simulated using the Bonded Particle Model（BPM） then the particles will fall off from slope under rainfall action for the bond between two particles will break. We obtain the general breakage shape of two kind slopes,and the critical erosion velocity is considered by setting the scour criterion. The failure mode of clay and sand slope is not exactly same. Due to the bonding effect between particles clay slope will failure by particles in aggregate or in block or flaking. Meanwhile particles of sand slope peel off from slope parallel to slope surface that is the formation of gullying. The simulation results are consistent with the actual physical model,and provide a reference for the prevention and control measures of the embankment slope.