Periodic Assessment and Long Term Durability Consideration of Drainage Galleries of Pandoh Dam, Himachal Pradesh, India using Non Destructive Test Method

S K Dwivedi, U S Vidyarthi, M Raja, C B Sarma

Concrete, Aging, diagnostic tool, ultrasonic pulse velocity, non-destructive testing.

Interaction of concrete with the persistent prevailing environmental condition will alter its material properties and cause deterioration. There are various causes of distress in the concrete structure, such as improper construction practices, post-construction expansion due to Alkali-Aggregate Reaction (AAR), corrosion of reinforcement, non-homogeneity of concrete, development of cracks due to shrinkage and thermal stresses, aging, etc. Such phenomena are very common in various elements of the dam. Pandoh dam is an earth cum rockfill dam 76.2 m high from the deepest foundation level. The dam is 255 m long and 12.19 m wide at the top, with a concrete spillway located on river Beas near Mandi in Himachal Pradesh. This dam was constructed in the year 1977 for irrigation and hydropower. Part of a run-of-the-river power scheme, it diverts the waters of the Beas to the south-west through a 38 km long system of tunnels and channels. The water is used for power generation at the Dehar Power House before being discharged into the Sutlej River, connecting both rivers. The objective was to assess and monitor the in-situ quality of concrete in a drainage tunnel under a spillway and other galleries in the dam's body to study the effect of excessive sulfate content in the seepage water from drainage holes. In this regard, Non-Destructive Tests (NDT) were conducted on drainage galleries of a dam by using the Ultrasonic Pulse Velocity (UPV) method to assess the in-situ quality of concrete.