Seepage from Trenches through Nonhomogeneous Soils

Infiltration from shallow trenches of arbitrary cross-sectional shape and through a layer of nonhomogeneous soil was studied analytically. The soil layer is underlain by a bed of gravel that is represented mathematically by a line of constant pressure. The basic flow equations were derived and the corresponding boundary value problems constructed by use of the perturbation theory. The effect of an exponential variation of the hydraulic conductivity on the quantity of seepage and the free surface is determined. A comparison with the case of constant permeability is made for different layer thicknesses. A triangular trench was chosen to indicate the effect of trench dimensions on the amount of seepage through layers of nonuniform permeability. Curves are presented to illustrate this effect.