Water and Energy InternationalYear : 2007, Volume : 64, Issue : 1
First page :
Last page :
ISSN : 0000-0000.
Design of underground power house caverns of Tehri HPP
Sharma R.K., CMD, Prasad G.M., GM (D), Singh Shailendra, Sr. Manager (D), Routela T.S., Sr. Manager (D)
Tehri Hydro Development Corporation, Ltd.
The underground powerhouse complex of Tehri Dam Project involved the construction of multiple large cavities in close proximity to one another. Design of principal cavities of machine hall and transformer hall required assessment of stress strain state and deformation around the cavities, resulting due to natural ground conditions with due consideration of closeness to other large cavities and construction sequence followed for the excavation of the cavities. At the DPR stage the problem was analysed by two-dimensional analysis using finite element technique for both linear and non-linear models. The study was helpful in evaluating different variants of support system in respect of their effect on depth of plastic zones forming in the rock mass around the cavities as well as the deformations at the boundary of the caverns. The effectiveness of selected scheme of supporting the roof arch and side walls of the machine hall and transformer hall cavities was substantiated by the results of the further studies carried out at the construction stage by incorporating actual geological and rockmass conditions encountered as well as the actual construction sequence adopted at site. Hoek and Brown (1997) failure criterion was used to estimate the rock mass strength parameters for the model analysis and the model results validated with the field measurements.
This paper describes the methodology of the design of large underground caverns. The design process involved continuous evaluation of rock parameters, detailed 2Dand 3D numerical modelling and monitoring program. The paper briefly also describes theTehri power house complex, its geological and geotechnical assessment, stabilization measures adopted, numerical modelling coupled with instrumentation scheme etc.