Modelling the impact of deterioration on the long-term performance of Dublin Tunnel

The influence of tunnel deteriorations like hydraulic and mechanical deterioration on its long-term performance has re-ceived extensive attention recently. Most studies considered deteriorations by manually varying the magnitude of parameters like permeability and stiffness, often neglecting their time-dependent variation process (individual/coupled). This paper ad-dresses this gap by investigating the impact of time-dependent hydraulic and mechanical deteriorations on the long-term behaviour of the aging Dublin Port Tunnel (DPT). Relevant geotechnical and mechanical properties of ground layers and concrete lining were firstly characterised and determined. A modified analytical relative ground-lining permeability model and calculated deteriorated lining permeability for DPT were presented, with steps and procedures generalised. The deteriorated permeability of DPT was incorporated into the hydraulic deterioration model thereafter, together with tunnel mechanical deterioration, offering a more holistic and realistic prediction of DPT’s deterioration-induced long-term performance than previously available. Numerical results, compared against field measurements, showed that (1) assuming constant tunnel permeability during its lifetime fails to accurately capture time-dependent liner deformation, and hydraulic deterioration has been identified as the dominant factor inducing an approaching squatting deformation mode, which can be attributed to twin tunnel interaction effect; (2) continuous mechanical deterioration leads to a linear growth in both vertical and horizontal convergence over time, with vertical convergence being more pronounced, indicating a squatting contraction deformation mode that could be associated with reduced ability to support ground pressure and external loads; and (3) the comparison quantita-tively evaluates the impact of individual and coupled hydro-mechanical deterioration on DPT’s long-term behaviour and the agreement between field data and numerical results confirms that coupled lining deterioration is the root cause behind the monitored lining deformation.