PERFORMANCE STUDY OF INSTRUMENTED UNDERGROUND POWER HOUSE CAVITY AT LAKHWAR

Abstract

Power constitutes the basis of infra-structure for the development and material progress of any community. With this basic objective in view, the Lakhwar concrete Dam ,204 m. approx. in height, is proposed to be constructed across the river Yamuna at Lakhwar. It is a multipurpose project to be constructed for Irrigation and Power generation. An underground Power House of 3x100 MW installed capacity is to generate around 475 million units of energy annually. The overall size of the Power House Cavity to accomodate the turbines, generators and the main inlet valves is 130mx20mx46m.The Power House site is located within a band of traps for which the geological data were obtained by constructing a 6.2 mx 6.25 m adit passing through the crown of the Power House. Considering the disasterous effect of the failure of a underground Power House in terms of loss of life and property, it is essential to check the safety of the structure during and after construction by installing the Instruments i.e. Strain meters , Load cells and Borehole Extensometers. The performance of the Instrumented underground Power House cavity has been observed using various instruments as stated above. The analysis of the monitored data of 2-3 years duration leads to the following important conclusions- (1) The steel rib stresses vary from 400 to 700 kg/cm2 against the combined design stresses of 1077 to 1277 kg/cm2. (2) The observed roof pressures by load cells are in the range of 0.20 to 0.43 kg/cm2 whereas various theories