Structural design of precast TBM segmental lining reinforced by steel fibres
Dubai’s Deep Tunnel Storm Water System (DTSWS) project is intended to collect subsurface and storm water from about 500km2 of newly urbanising communities of Dubai, and to transfer the captured flow to the sea. The tunnel is a segmental lining tunnel excavated by TBM. The tunnel presents an internal diameter of 10m and 350mm of segment thickness and the use of steel fibres reinforced concrete in the precast segmental lining of this large tunnel. The use of fibres aims to reduce the CO₂ footprint obtaining a most optimized design from the environmental point of view. The paper presents the design of precast segments in order to ensure structural competence and integrity according to the durability requirements, under short terms and long terms loads. Hence, considering such complexities, the structural design has been carried out producing a 3D structural model by means of a sophisticate FEM structural software. For the circumferential joint, results of model allow to identifying areas of the segment where spalling and bursting stresses are generated along circumferential joints and maximum value of those stresses. Finally, a structural design verification of the segment has been undertaken considering the contribution of steel fibres class 4c, as is set up in the FIB model code, searching to ensure precast segments are structurally competent and fulfill the durability requirements of the Project. Damages during execution have been also reported.