Effect of orientation on stability of caverns - A numerical modelling study

Abstract

3D numerical modelling studies were carried out to study the behaviour of large twin caverns belonging to a hydroelectric project in Himalayan region. Various stages of extraction of the caverns were characterised by instrumentation studies. The cavern is oriented along the major principal stress direction. Numerical model results were in close agreement with the measured values in the field. Taking this model as the base, parametric studies were carried by varying the angle between cavern axis and direction of major principal stress. Alignment of the caverns were changed at an interval of 15o. Analysis was done for 12 orientations upto an angle of 165o. Maximum stress concentration factors for all orientations were obtained on the upstream side of powerhouse cavern, in the pillar between powerhouse cavern and transformer hall cavern and on the downstream side of transformer hall cavern. Similarly, the displacements in the walls of twin caverns were compared for all orientation of the caverns. � 2018 ISRM & SRMEG (Singapore).