Flow underneath a pair of structures with intermediate filters on a drained stratum

This paper presents a solution, using a conformal mapping technique, for the problem of seepage beneath two structures with intermediate filter built on two pervious strata. The lower stratum has a higher permeability than the upper one. Formulae are derived for calculating the dimensionless heads acting on both the upstream and downstream structures. Also, equations are derived for determining the values of the exit gradients along both the intermediate filter and the downstream bed, and the seepage discharges. For given boundary conditions, the seepage characteristics are calculated using the derived formulae; a sample from the results of such calculations is presented.