Factors affecting piping erosion resistance: Revisited with a numerical modeling approach

Piping poses a great threat to dam and levee systems across the globe. Although various straightforward approaches have been used to assess piping resistance, a fundamental understanding of the complex soil-flow interactions in this process is still lacking. Practitioners have traditionally relied on Terzaghi's theory to evaluate piping potential. In this study, the factors affecting piping resistance are revisited using a coupled computational fluid dynamics and discrete element method (CFD-DEM) approach. A series of simulations were conducted to investigate the effects of specific gravity, initial void ratio, particle size distribution, sample aspect ratio, and frictional coefficients. Analyses of simulation results show good agreement with experimental results in the existing literature providing demonstrative explanations for deviations of the experimental results from Terzaghi's theory. A key finding is that for laboratory experiments with soil samples in a container, the wall friction and the aspect ratio significantly affect the critical hydraulic gradients. The effects of the various soil properties are first analyzed on an individual basis; based on the numerical simulation results, a theoretical model for piping is developed that considers the previously mentioned factors.