Stability of Structures with Intermediate Filters

Until now no solution was available to determine the effect of plane drainage located anywhere between the two cutoffs. The problem is solved exactly by the use of conformal mapping. The equations for seepage discharge to the intermediate filter 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 filter of even very small length. The uplift pressures decrease on the downstream side and increase on the upstream as the filter is moved from upstream to the downstream side. The filter should be located such that total uplift on the floor downstream of the gateline is minimum. With increase in the depth of downstream cutoff, the uplift pressures increase only along the floor downstream of the filter.