How a suspended cut-off wall functions: Effect of soil anisotropy in a levee foundation

摘要

Suspended cut-off wall is widely used in levee and embankment engineering for preventing fromrnpiping failure. It has been identified for a long time to behave as increasing the seepage path and lowering the bulkrnhydraulic gradient. However, the beginning and development of piping relate to a variety of controlling factors,rnincluding local hydraulic gradient, soil texture, permeability, and size gradation. It is still far from completernunderstanding of piping phenomenon and thus how a suspended cut-off wall functions. This paper presentsrna numerical investigation into the progression of piping in a levee foundation, focusing on the effect of thernanisotropy of soil hydraulic permeability.A coupled modelling of seepage-piping flow domains was performed.rnAn element-free Galerkin algorithm was adopted for deal with the internal dynamic boundary between the tworndomains. The anisotropy in hydraulic permeability was found as the other dominant mechanism that a suspendedrncut-offwall functions. Itwas shown to increase the difficulty of piping progressionwhen the proceeding directionrnis turned around a cut-off wall. The interrelation between the seepage path increase due to a cut-off wall and therneffect of soil anisotropy was analysed. The results would be helpful for the design of seepage control measuresrnfor levees and embankments.