Effect of Drains on Pressures Below Structures

Until now, no closed-form solution was available to determine the effect of deep drainage located below a flat floor with a cutoff. The problem is solved exactly using conformal mapping. The equation for seepage discharge to the drain and uplift pressures below the floor are given. These equations have been solved numerically to obtain pressures at key points. The results are given in the form of easy-to-use design curves. The uplift pressures reduce considerably along the entire profile of the structure with the provision of drain of even very small depth. The uplift pressures decrease on the downstream side and increase on the upstream as the drain is moved from the upstream to the downstream side. The drain should be located such that total uplift on the floor downstream of the gate line is minimum.