Geological and Geotechnical Approach for Excavation of Large Unlined Rock Cavern

The degree of uncertainty involved in an underground storage project is relatively higher compared to other underground projects. In order to allow for a safe and economical construction of underground rock caverns, continuous updating of the geological and geotechnical model along with adjustment in construction approach is required. Investigations planned during different stages of excavation of the project assist in the identification of various geological features and ground characteristics to ensure robust design of underground structures. Investigation in each stage of the project is planned in line with the time and money available at that stage, along with level of detailing required for different design stages. In order to develop an efficient investigation scheme, it is necessary to assimilate the existing information from one stage before planning for the next stage of investigations. This article highlights the significance of various investigations carried out for one of the strategic storage site in the southern part of India.