Misra R.N.,Satluj Jal Vidyut Nigam Ltd |
Chauhan R.S.,Satluj Jal Vidyut Nigam Ltd |
Pathak V.K.,Satluj Jal Vidyut Nigam Ltd |
Sharma R.K.,Satluj Jal Vidyut Nigam Ltd
Water and Energy International | Year: 2011
In Hydro Electric Projects, grouting plays an important role in controlling the seepage and improvement in rock strength for the construction of underground as well as surface structures. Factors such as the geological characteristic of the rock, depth of structure, groundwater levels, and surface access for grouting equipment will determine the approach or combinations of approaches best for a specific project. When hydroelectric projects are located in the Himalayan region, where the geological conditions are fragile, the role of grouting during construction assumes a greater significance. The Nathpa Jhakri Hydroelectric Power Station (NJHPS) 1500 MW, the largest hydropower station in the country under operation, and downstream Rampur Hydro Electric Project (RHEP) 412 MW, presently under advance stage of construction, and planned to run in tandem are both located on river Satluj in the Himalayan region. The extensive grouting operations carried out on these projects have been outlined in this paper. This includes a case study of the grouting experience at Nathpa dam for consolidation of foundations, treatment of weak mica rich seams, provision of grout curtain for control of excessive seepage and grouting associated with installation of 200 MT prestressed cable anchors for stabilisation of slopes. Further the experience in grouting associated in 10.15 dia 27.4 km long Head Race Tunnel (HRT) of NJHPS and 10.5 m dia of 15 km long HRT of RHEP has been outlined, which included pre grouting in critical areas like in low cover reaches under Manglad stream in NJHPS and under river Satluj crossing in RHEP, pre injection grouting in exceptionally poor rock etc. Importance of grouting for controlling subsurface flow from water bodies to deep excavation and role of grouting in slope stabilisation has been covered with specific reference to RHEP. The grouting experience gained in these two major projects of SJVN can be gainfully utilised in other upcoming hydroelectric projects located in the Himalayas.