Geological and geotechnical assessment for an underground powerhouse and recommended support system, Chamera Hydroelectric Project, stage-II, H.P.

Chamera H.E. Project, Stage-II, H.P. marks a milestone in the history of development of hydropower in India being the first of its kind where all civil works were completed within three and a half year duration. The project is housed in a domain of phyllites/phyllitic quartzites & quartzites of Chamba Formation. An underground powerhouse, located in the right bank of river Ravi is designed to generate 300 MW (3×100) of power. The underground cavern was aligned in N30°E-S30°W direction taking the geological environment into account. Adequate support measures including high tensile Dywidag rock bolts were provided, taking into consideration the expected rock stresses. The paper outlines the geological suitability for the underground structure, the optimum support system of rock bolts on the basis of geological conditions.