Estimation of Uplift in Cracks in Older Concrete Gravity Dams: Effect of Head Losses in Drain Pipes on Uplift

Abstract

The effect of head losses in drain pipes on crack uplift and drain effectiveness has been added to the analytical solution proposed in the first of this sequence of papers. Although drainage wells are effective in reducing crack induced uplift pressures, it is found that their effectiveness can be reduced if head losses in the drain pipes are significant. This reduction seems to be important only for drains with diameters less than 4 in. (101.6 mm) and smooth cracks with larger apertures. It is found that the increase in drain effectiveness with the drain radius is more important when head losses in the drain pipes are taken into account then when they are neglected. Cleaning of drains is recommended in order to prevent a decrease in their effective radius and to ensure their continuous effectiveness.