土与反滤层接触面上入渗角对反滤效果的影响

he seepage direction inside the dam usually changes due to the different seepage positions and the fluctuation of upstream and downstream water levels.The infiltration angle of the seepage flow on the contact surface between the protected soil and the filter is not orthogonal.Because of the great difference of permeability coefficient between the dam material and the filter,the seepage angle causes the change of hydraulic properties of the contact surface,which will affect the filter performance.In this paper,the PFC-3D is used to establish the numerical models of 30,45,60 and 90 between the seepage direction and the contact surface.By simulating the real-time invasion rate of the protected soil particles and the depth of their movement into the filter,the contact erosion and filter effect under the action of different seepage directions are studied.The results show that in the initial stage of seepage,the difference of invasion rate and invasion depth of protected soil particles in different seepage directions is small; with the increase of seepage time,the invasion rate at 90is relatively stable and the value is small,the invasion depth and seepage velocity at the contact surface are the smallest,and the filter has a strong ability to block the movement of protected soil particles.The filter effect decreases at 60,45 and 30,indicating that the larger the angle between the seepage direction and the contact surface,the better the filter effect.The reasonableness of the calculation results is discussed by using the principle of seepage refraction,and compared and analyzed with the experimental results of relevant literature,and it is considered that the change of seepage infiltration angle at the contact surface between the fill and the filter should be paid attention to in water conservancy projects such as embankment dams,especially the fact that the small angle of infiltration flow at the interface has a greater influence on the filter effect.