Numerical solutions for tile drainage of layered soils

Abstract

The problem of the tile drainage of a uniform soil lying above an impermeable layer is solved by the relaxation method and compared with the analytical solution. The error in flow found by the relaxation method is less than four per cent, with greater accuracy obtainable if a finer net is used. The method is readily adaptable to complex problems involving layers of different permeabilities. As an example, the problem of the tile drainage of a two‐layered soil with surface soil used for trench backfill, for which no analytical solution exists, is solved numerically.