Design Aspect of a Dam Without Joint – Chamera-III Power Station

This paper provides aspects that have been dealt while executing the design of dam at Chamera- III, Power Station. The special feature of the Dam of this project is the absence of joints between spillway bays. This choice has been dictated due by site constraints. As the valley is very narrow, all the dam blocks are planned as overflow bays with deep seated spillway and a common pier arrangement to avoid slope excavation of large height. This led to dam without joint. The dam was founded on competent rock and no major shear seams or weak zones have been encountered in foundation, thereby minimizing differential settlement. Further, absence of non-over flow blocks along with deep-seated spillway resulted in significantly less quantity of mass concrete thereby easing management thermal stresses. Temperature monitoring during the construction was undertaken to check the actual thermal behaviour vis-a-vis predicted to take remedial measures, if required. All the bays of main spillway were designed as a single monolith and it was ensured that they are constructed simultaneously without any differential lifts. The dam has been performing as envisaged. This is a unique example which may be adopted if site condition and layout requirement permits.