ABSTRACT
Sprayed Concrete Lining (SCL) is a well-established method for tunnel construction throughout the world, sometimes referred to as NATM (New Austrian Tunnelling Method) or SEM (Sequential Excavation Method). An SCL tunnel usually consists of a primary and a secondary lining. The primary lining is often designed to support all ground loading during construction. Subsequently, a drainage layer or waterproofing layer is installed depending on the type of tunnel. The secondary lining is then constructed in the final stage to carrying permanent loadings with or without the benefit of the primary lining. Risk adverse owners typically require a load case with full degradation of the primary lining in long-term condition. The tunnel lining geometry is developed based on the functional requirements of the projects, as well as considerations such us geology, location, built environment. These considerations can result in complex junctions and highly variable lining thickness. To analyse the structural response and carry out a code-based design of a tunnel lining with a complex and variable geometry, elaborate numerical modelling and detailed workflows for data pre- and post-processing are required, often leading to numerous design iterations. This paper presents the key digital tools introduced in the detailed design workflow of primary and secondary linings with a highly variable geometry in SCL tunnels, caverns and cross-passages. These tools support the lining design throughout the whole process, from the definition of the critical design sections and generation of meshes for 2D/3D FE modelling to the final verification stage, thereby leading to a significant reduction of the design time and optimisation of the lining thickness and reinforcement requirements.
