Multi-LoD BIM integrated design framework for pressurised tunnel: Hydro-mechanical coupling simulation and sustainability assessment

With increasing population growth and rapid urbanisation, humanity faces the urgent challenges of climate change, necessitating transformative actions in the infrastructure and energy sectors to ensure sustainability for future generations. The renewed global emphasis on developing and utilising hydropower, particularly through pumped hydro energy storage (PHES) systems, is pivotal in advancing the transition to Net Zero emissions. Tunnel Boring Machines (TBMs) are extensively employed in tunnel construction for the energy sector. However, several critical challenges persist throughout the lifecycle of these vital projects. These include the lifecycle assessment of the mechanical performance and embodied carbon of segmental linings, influenced by geometric factors such as tunnel alignment and diameter, fabrication patterns, and joint stiffness. Furthermore, the long-term hydro-mechanical performance of pressurised tunnel linings is significantly affected by variable internal water pressures and surrounding rock conditions. This paper proposes an integrated framework for TBM tunnel design, utilising multiple Levels of Detail (multi-LoD) Building Information Modelling (BIM) to systematically address these challenges and enhance the sustainability and resilience of underground infrastructure. Algorithms for both parametric modelling and pre-processing are developed to ensure the interoperability between BIM and numerical models. The mechanical response of segmented linings under various internal water pressure is investigated to analyse the composite behaviour of reinforced concrete segments, joints, lining gaps, secondary linings, and rock mass under internal pressure. The robustness of the framework is implemented into a use case analysing the deformation and waterproofing performance of a segmental lining structure under high internal pressure and complex geological conditions. Four cases with various reinforced concrete lining designs, featuring differing thicknesses of secondary linings and tunnel alignments, are analysed. Additionally, embodied carbon assessments are conducted for each case, and design optimisation is performed based on numerical modelling and sustainability assessment results. The integrated framework detailly illustrates how multi-LoD BIM, hydro-mechanical coupling, and embodied carbon accounting can be effectively combined to enhance the sustainability and efficiency of TBM tunnelling projects.