REHABILITATION AND IMPROVEMENT WORKS OF BHADRA DAM

TREATMENT OF THE UPSTREAM FACE THE DAM FROM LEVEL 2166 FT. TO 2102 FT. SPILLWAY, SPILLWAY PIERS, ABUTMENTS, DRY WELLS, REAMING OF POROUS HOLES, FOUNDATION DRAINAGE HOLES - GROUTING TO FOUNDATION, BODY OF THE DAM, EXTRACTION OF CORES FOR CONDUCTING PERMEABILITY TEST & REPAIRS TO NAPPE PORTION OF SPILLWAY

This is a masonry dam that had an acute problem of water seepage from the upstream. The water seepage was threatening the integrity of the dam. The mortar in the entire upstream face of the dam was old, cracked and infested with algae & fungi. Also, there were cavities in the overflow section of the dam and the surface of this area was badly damaged.
The rehabilitation work was started by repair of the upstream face, which was done using high strength, polymer-modified, UV resistant mortar. Due to the typical shape of the dam, manual ‘jhulas’ were fabricated to lower the labourers for cleaning & repairing the upstream face. The algae & fungi were manually scrapped and removed by use of a cleaning agent. The chipped area was cleaned with a high-pressure water jet & air and new mortar was filled in the cavity & dressed properly.
The rehabilitation involved repair of the damaged ogee by filling the cavities by high strength micro- concrete, the leakages in the overflow portion was treated by use of 2 component polyurethane.
There was high seepage in the gallery through a few porous holes, which was treated from inside the drainage galley with the use of fast setting admix and special polymers. The dam body, which had become porous due to the leaching of mortar, was consolidated by carrying out drilling and grouting from the top of the dam.
Under this work, porous drains in the dam body were reamed using high-pressure water jets and diamond bits. The drainage holes were drilled from the drainage gallery to release any uplift pressure in the dam foundation.