The existence of large hydraulic gradients in regions of an earth dam
where fine-grained soils are inadequately filtered can sometimes lead
to internal erosion and piping failure. This paper investigates the st
ochastic nature of hydraulic gradients through two different earth dam
cross sections, both with simple drains. In particular the magnitude
and location of maximum hydraulic gradients are studied via Monte Carl
o simulation to derive their probability distributions and assess thei
r variability. These results can be used to guide designers with respe
ct to minimizing the risk of internal erosion in the presence of uncer
tain soil permeability. The effect that the stochastic nature of the p
ermeability field has on the hydraulic gradient distribution is compar
ed to hydraulic gradients obtained in the deterministic case. This ena
bles an evaluation of the importance of considering permeability rando
mness in the design process.