Safety and Stability Monitoring of Underground Structures - Role of Geotechnical Instruments

Construction of large underground caverns and tunnels are playing vital role in development of the nations around the globe, in various sectors like mining, hydropower, irrigation, transportation, water supply, oil storage, sports, nuclear and defense sectors. The limited space availability and environmental concerns are some of the reasons in opting for underground structures. Successful construction of these in even, at highly varied geological areas is possible with implementation of innovated construction methods along with monitoring techniques. The use of geotechnical instruments is playing major role in monitoring and assessing the stability of the structures during excavation. The changes in deformations and loads while excavation can be measured, and this guides the stakeholders in decision making during critical stages of construction. Like in other fields, during past few decades geotechnical instruments are also transformed from simple mechanical systems to sophisticated real-time monitoring systems. The monitoring data will be used for calibration of the numerical models prepared to understand the response of the ground to excavation stages. It will also help in assessing the performance and behaviour of the ageing structures, with long-term monitoring. Improved construction control and safety monitoring can be achieved with comprehensive instrumentation and field measurements. In this paper, how the stability of some of the underground structures are evaluated based on the actual instrumentation data during construction and post constriction period is explained. The recent developments in instruments and its application, and selection of instruments based on the ground conditions, benefits achieved during construction in some of the underground structures is also explained.