Stability Analysis of Powerhouse Caverns of Bakhtiary Dam Using 3DEC Software

Today، large underground spaces for multiple strategic projects including hydroelectric power plants، storage of oil and gas، nuclear waste disposal، etc. are important. Stability analysis is of great importance due to the large dimensions of these spaces. In this paper، at first according to the discontinuities orientation and stress conditions of the region، appropriate direction for excavations is selected. The rock mass strength properties including the shear strength of discontinuous rock mass and the modulus of deformation using in situ tests was determined. The numerical modeling results have been summarized. Stress conditions in the study area were determined using a hydraulic fracture tests. In the next step، Using analytical relations and numerical method (Discrete Element Method، 3DEC); as well as، with regard to occurring rock burst phenomenon between the two caverns، and changing of distance between these caverns، the proper optimum distance is determined. Finlay using the result of numerical modeling and based on the plastic zone، a suitable support system (consists of length of tendons and rock bolts at different parts of caverns and axial stress applied to those) has been suggested.