Publications / 2014 Proceedings of the 31st ISARC, Sydney, Australia

Geotechnical Monitoring for Safe Excavation of Large Rock Cavern: A Case Study

A.Mandal, C. Kumar, A. Usmani, A. Nanda
Pages 960-965 (2014 Proceedings of the 31st ISARC, Sydney, Australia, ISBN 978-0-646-59711-9, ISSN 2413-5844)

The present study highlight the methods used to monitor the geotechnical behaviour and performance of the cavern during excavation in order to verify and, if necessary, adjust the rock support to ensure safe construction at every stage. The present geotechnical monitoring practice for underground structures involve convergence monitoring with the help of optical targets and rock mass displacement with help of bore hole extensometers. More importantly it involve detailed planning to finalize the position of each monitoring instruments based on location and orientation of geological features. Further it is equally important to ensure proper recording of monitoring data in order to analyze and take immediate action in case of any adverse situation. This requires a dedicated high end automated software, which can record, analyse and produce significant results out of large quantity of recorded data which otherwise turns out to be only ravage. Initially geotechnical monitoring was carried out in recently excavated zone of cavern on daily basis. Further based on continuous monitoring data for at least one week, frequency of monitoring is further decided. In most of the cases the deformation of rock mass was quite less compare to the alarming values which were evaluated based on detailed design for different rock classes.

Keywords: Underground excavation, Cavern, Tunnel, Geotechnical Monitoring