Presence of tail-water in a gravity dam ____________________

The principal stress is given by the formula – P = Pv sec(Φ)2 – p’ tan(Φ)2 where Pv is the intensity of vertical pressure and p’ is the tail-water pressure The shear stress on the horizontal plane near the toe is given by – S = (Pv – p’) tan(Φ) From both the equations, it is clear that the tail-water pressure is opposite in nature and it reduces the value of principal stress and shear stress.