ANALYSIS OF NATHPA JHAKRI UNDERGROUND POWER HOUSE CAVITY

Abstract

The design of underground cavern requires the knowledge of stress field, developed as a result of redistribution of insitu stresses, consequent upon the excavation of rock mass. The zones of compression and tension are delineated and the points of local stress concentrations are identified once the stress field has been defined. The parameters influencing the redistribution of stresses around an opening in rock mass include its shape, the magnitude and direction of insitu stresses, strength and mechani-cal properties of rock mass and the stage of excavation. The sta- bility of the underground structure depends upon the local stress concentrations as well as the stress gr=adient around the opening. The stresses should be within allowable limits and steep stress gradients are to be avoided. Thus, extensive stress analysis, incorporating the parameters described above, is necessary to ensure the stability of cavern and to select best possible shine, layout and sequence of excavation.