Abstract
The paper describes the expansive phenomena affecting Lilla tunnel in Spain during construction and subsequent operation. The geology of the site and the performance of alternative support designs are described. Field observations are analysed to identify the causes of the observed swelling. It was found that long-term swelling in Lilla tunnel was the result of gypsum crystal growth in discontinuities. The phenomenon was a consequence of a few contributing factors: significant presence of anhydrite, existent or activated discontinuities, and the circulation of water. These conditions were present in the highly tectonised Tertiary claystone in Lilla. The original horseshoe cross-section was transformed into a circular one, and a reinforced concrete lining was built to resist swelling pressures. Long-term monitoring of the reinforced tunnel provided valuable data on the evolution of swelling pressures against the lining, and on the stresses developed in the resisting structure. The highly heterogeneous distribution of swelling pressures against the lining explains the low strains measured in reinforcement bars despite the very high maximum swelling pressures recorded.
Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
