Engineering Geological Investigations and Assessments of Support System of Delivery Mains of Package-6 of Kaleshwaram Lift Irrigation Scheme, Telangana State, India

Detailed engineering geological and geotechnical investigations were carried out of the delivery mains for assessment of rock mass qualities and to provide a sound support system. Seven numbers of delivery mains are constructed which are an important component of the pump house complex for lifting water from the pump house to the delivery cistern. Regionally the rock types belong to Karimnagar Granulite Terrain (KGT) and Peninsular Gneissic Complex (PGC) of Archean age. The main rock types of delivery mains are medium to coarse-grained grey granite and charnockite traversed by dykes/basics enclaves. The rock mass was classified on the basis of rock mass rating (RMR) and tunnelling quality index (Q) classifications. The calculated classes of rock masses range between very poor to good. Geomechanical properties of the rock samples were tested as per IS codes. Delivery mains were constructed as per the Norwegian method of tunnelling (NMT) and support design as per the Q-system chart. Rock support in the form of rock bolts, steel fibre reinforced shotcrete and grouting arrangement were applied. The main challenge for the construction of seven delivery mains was the less rock ledges in between these delivery mains and presence of nearby live reservoir. So, before excavation, data was collected from adits and pump house heading portion to classify the rock masses of delivery mains. In this paper engineering geological investigations, challenges and design of rock support system is described in detail for seven delivery mains.