When soil heterogeneity helps the geotechnical design: the case of drainage trenches

Experience shows that often even advanced geotechnical models cannot fully match the hydraulic or mechanical soil response due to unexpected variability of both soil structure and properties even within short distances. Engineers are then called to assess the influence of soil variability in the solution of geotechnical problems. This paper shows that in some cases, as in the design of drainage trenches, unforeseen layering favours a better soil response than in homogeneous conditions making the drainage system more efficient than foreseen.