FOUNDATION TREATMENT OF THE GRAVITY DAMS

• The foundation of the gravity dam should be hard, strong, durable and impervious.
• The imperviousness of the foundation is very important as uplift pressure depends greatly upon the seepage.
• Uplift pressure is increase when seepage is more.
• Hence to render the foundation water proof or impervious, it has to be suitably treat.
• All the loose overlying soil from the site is removed and solid rocky foundation is reach.
• The rocky foundation should also be excavated for some depth so that the proposed dam fits in the rock.
• This aspect will prevent the sliding of the dam over its foundation.
• A 3 cm thick layer of rich cement mortar should be laid on the excavated rocky foundation before concreting is done over it.
• All the faults, seams, cavernous rocks, crushed zones etc., should be either made good or removed from the foundation site.
• In order to prevent seepage through foundation, trenches may be excavated near heal of the dam and filled with cement concrete.
• Holes are drilled covering whole of the foundation and filled with cement grout.
• If the foundation is to be treated for large depths, the holes are also drilled for large depth.
• The holes are filled with cement grout in stages.
• Any other fault noticed in the foundation is rectified.