Retrofitting of Distressed Structure (Coal Handling Plant) of a Thermal Power Plant – Case Study
One of the thermal power plant in Uttar Pradesh went for the expansion & augmentation of their existing power generating capacity by constructing additional 2x250MW power generation facility. Various services under construction include conveyors, crusher house, wagon tipplers etc. The construction of coal handling plant and associated facilities, the Transferring Point tunnel (TP 3), was completed during the month of July 2010. During some heavy rains in the month of September, the tunnel & its surroundings were completely inundated with rain water. The surrounding area got flooded & the whole structure got immersed in water. With the flood water being pumped out, the level receded. Some minor cracks in and around the ventilation duct were observed by the contractor. The ground water level at this point was lowered to a depth of -13 metre by pumping out the tunnel water through peripheral bore holes & surface pumps. On removing the top & back filling, the structural distress comprising big crack could be noticed near the A/B section.
The agencies working on this project approached the author for a comprehensive rehabilitation report including causes of distress & its rectification.
Accordingly, the author visited the site on the request of the client & EPC contractor, studied the geographical soil pattern & construction methodology adopted in constructing the tunnel. With the discussion with site engineers, board officials, Government agencies such as NTPC, a methodology was devised and implemented.
The following write up discusses various parameters such as the cause of distress & suitable methodology to rectify the same.
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