Monitoring of an existing concrete-lined tunnel at CERN excavated in the molasse rock

K. Soga, V. Di Murro, L. Pelecanos, C. Kechavarzi, L. Scibile, J. A. Osborne, R. F. Morton

Research output: Chapter or section in a book/report/conference proceedingChapter in a published conference proceeding

Abstract

At the European Centre for Nuclear Research (CERN), the well-known deep particle accelerator is hosted in a circular underground facility excavated in the weak sedimentary rock mass, in Geneva basin. Aged concrete tunnels commonly exhibit tunnel lining deterioration with time, enhancing long-term tunnel distress and, hence, compromising the performance of physical experiments. Recent changes in the ground water flow regime around the tunnel have brought challenges to the operation of an existing horseshoe concrete-lined tunnel housed within the underground facility at CERN. Due to extreme weather conditions, large amounts of water flowed towards the tunnel, resulting in the long-term hydraulic deterioration of the drainage system, such as the clogging of the drains. As a result, some tunnel cross-sections are experiencing a vertical tunnel elongation as a mechanism of deformation. This paper presents the investigation carried out for CERN TT10 tunnel that underwent damage many years after construction. Field monitoring instrumentation has been conducted to assess the tunnel lining behavior, using both conventional total stations data and advanced distributed fibre optic strain sensing (DFOS). The observational data results show that the tunnel lining experiences compressive stresses at the tunnel crown and tension cracks at the tunnel shoulder, whereas the tunnel floor exhibits heaving. Furthermore, more significant changes in tunnel diameter were observed for certain tunnel sections where the very-weak swelling-potential marl layer is encountered.

Original languageEnglish
Title of host publicationGeotechnical Aspects of Underground Construction in Soft Ground - Proceedings of the 10th International Symposium on Geotechnical Aspects of Underground Construction in Soft Ground, IS-CAMBRIDGE 2022
EditorsMohammed Z.E.B. Elshafie, Giulia M.B. Viggiani, Robert J. Mair
Place of PublicationU. S. A.
PublisherCRC Press
Pages177-183
Number of pages7
Edition1st
ISBN (Electronic)9780429321559
DOIs
Publication statusPublished - 11 May 2021
Event10th International Symposium on Geotechnical Aspects of Underground Construction in Soft Ground, IS-CAMBRIDGE 2022 - Cambridge, UK United Kingdom
Duration: 27 Jun 202229 Jun 2022

Publication series

NameGeotechnical Aspects of Underground Construction in Soft Ground - Proceedings of the 10th International Symposium on Geotechnical Aspects of Underground Construction in Soft Ground, IS-CAMBRIDGE 2022

Conference

Conference10th International Symposium on Geotechnical Aspects of Underground Construction in Soft Ground, IS-CAMBRIDGE 2022
Country/TerritoryUK United Kingdom
CityCambridge
Period27/06/2229/06/22

Bibliographical note

Funding Information:
The authors would like to acknowledge the SMB-SE group at CERN for the financial assistance provided during the research project and the CERN EN/SMM Group for providing the conventional monitoring data. The research was conducted in collaboration with the Centre for Smart Infrastructure and Construction (CSIC) of the University of Cambridge (funded by EPSRC and Innovate UK) and the University of California, Berkeley (USA). The valuable contribution of the CSIC technical team for transferring the knowledge regarding the fibre optic sensing technique and for the assistance provided during the DFOS installation is acknowledged.

ASJC Scopus subject areas

  • Civil and Structural Engineering
  • Building and Construction

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