ABSTRACT
This paper explores the challenges of designing and conducting numerical analyses for fully composite sprayed concrete linings (SCL) in tunnel junctions, with a focus on complex projects such as Crossrail. A key aspect examined is the discrepancy between the expected behaviour of a composite SCL configuration, as outlined in the design, and actual data gathered from fibre optic monitoring. Despite extensive efforts, the underlying cause of this discrepancy remains unclear. The study reviews Crossrail’s design approach and a recent back-analysis methodology, identifying reasons for the incorrect stress distribution between concrete layers. A novel numerical modelling technique is introduced to simulate sequential construction effects in fully composite SCL systems. Back-analysis demonstrates that this modelling approach successfully generates the correct stress distribution. It is hoped that this paper will encourage the use of volumetric approaches in future numerical analyses of fully composite linings.
