基于离散元法的接触冲刷影响因素研究

Study on the Effect Factors of Contact Erosion Based on Discrete Element Method

成层土间容易发生接触冲刷破坏,对水工建筑物的安全运行有不利影响。为此探讨了粗层孔隙率、粗层颗粒形状和剪切位移对接触冲刷的影响,采用离散元法对成层无粘性土进行了接触冲刷数值模拟,得到以下结论:粗土层孔隙率的增加对土层抗渗流冲刷不利,对于D10/d10比值为10的土层,当粗土层的孔隙率相对较大时,在一定的渗流压力作用下,试样的渗透流速在初始阶段会有一定减小,随着细颗粒流失比的不断增大,渗透流速也随之增大,土层结构发生较大改变,也会发生接触冲刷破坏,在工程实践中应该引起一定的重视;当粗层颗粒形状为非球形时,细土层颗粒流失比减小,土层抗冲刷破坏能力有所提高;剪切变形后试样中粗土层孔隙率会有一定增大,孔隙结构也会发生改变,细土层颗粒流失比增大,加剧了土层发生接触冲刷破坏的风险。

Contact erosion easily occurs in soil layers,which influences the safety of hydraulic structures.The effects of several factors on contact erosion,such as porosity of coarse layer,particle shape of coarse layer and shear deformation,were explored based on discrete element method for cohesionless soil layers.The results show that the increasing porosity of coarse layer is bad for the resistance of contact erosion.When D10/d10 of the soil layers is about equal to 10,contact erosion may occur if the porosity of coarse layer is large enough.The flow velocity of numerical sample first slightly decreases at the beginning of contact erosion.With the continuous increase in the erosion ratio of fine particles,the flow velocity gradually increases and the soil structure has an obvious change,which is bad for the seepage resistance of contact erosion and should be paid more attention in practice.When the soil particle shape of coarse layer is non-spherical,the erosion ratio of fine particles decreases and the seepage resistance of contact erosion is higher.For numerical samples under shear deformation,the porosity of coarse layer increases and the pore structure changes,so more fine particles are eroded and flow out through the pores of coarse layer during contact erosion simulation,which increases the risk of seepage failure.