Effect of soil composition on piping erosion of earthen levees

摘要

Internal erosion processes due to piping in an earthen levee built in a laboratory flume are reported in this paper. Different sand, silt and clay mixtures are used for constructing the levee. An image processing technique using an edge-detection algorithm is successfully applied to track the erosion process from the recordings of both side and bottom views. The change in the depth of erosion during the piping phenomenon for different soil composition is studied. The results show that small changes in clay content in the soil mixtures significantly affect the erosion rate. The average depth is approximately equal to the average bottom width of erosion in the piping zone. An exponential equation to estimate the depth of erosion as a function of time and the coefficient of soil erodibility is presented. Results for the critical shear stress and the coefficient of soil erodibility agree well with those obtained from the hole erosion test but not with those obtained from the jet erosion test.