Effect of in-situ stress on mechanical behavior of rock-anchoring tendons in underground caverns

Large underground caverns are used for a variety of purposes in rock engineering. These include caverns housing turbines, electrical generators and transformers in hydroelectric projects, caverns for storing liquid or gaseous fuels, underground warehouses and underground sports facilities. Rock-anchoring tendons is one of the most effective supporting system to control rock mass failure in underground excavations. However, in the deep underground excavations failure of the tendons has been frequently reported. The purpose of this study is evaluation of the effect of in-situ stress on the mechanical behavior of rock anchoring tendons. For this aim, Raghun underground power cavern located in Tajikistan's Dushanbe was studied as case study. An accurate 2D model is prepared by FLAC 2D V. 7.0 and the sidewall convergence of cavern is compared with the monitoring data recorded from 1989 to 2015. In the next, effect of in-situ stress on the mechanical behavior of tendons in cavern’s wall is considered and it is found that with increasing the cavern depth, the effect of pre-stress on the reduction of wall deformation decreases.