Seepage computation methods for landside seepage berms on two-stratum dike foundations with impervious boundaries

The constructions of seepage berms are the most common measures against sand boils in dike projects. Under the condition of deterministic water head at downstream boundary of pervious foundation, seepage computation methods had been suggested by several researches. However, downstream boundary condition in the pervious foundation maybe impervious in practical engineering, and there has not been studies for such cases before. This paper works out formulae for seepage computations of seepage berms with low-permeability and high-permeability on finite and infinite two-stratum dike foundations with impervious downstream boundary. In these formulae, the permeability of berm embankment can be arbitrary and the safety factor for seepage control at the two ends of the berms can be different. In addition, parameters affecting berm thickness and length are discussed. The paper also gives some suggestions on the selections of berm soils and acceptable safety factors for seepage control, which can be referred in future dike design.