Mechanical performance of the prestressed concrete lining withstanding prestress of steel strands: Full-scale test and numerical simulation

With the increase of internal water pressure on a water-delivery shield tunnel, the design and construction of prestressed concrete lining become more complex. One of the issues is the secondary tensile stress of concrete that could induces the cracks of concrete lining during the prestress tensioning of steel strands. Combined with a full-scale experiment conducted outside the project tunnel, a 3D finite element model (FEM) is developed to simulate the real process of the concrete lining withstanding the prestress of steel strands and the variations of the circumferential and longitudinal stresses of concrete lining are comparatively analysed. Results show that the circumferential compressive stresses in the inner and outer layers of prestressed concrete lining are maximum at the completion of the last tensioning step of steel strand, the small differences between the average values of them indicate a uniform distribution along the thickness. Three sections are given where longitudinal stresses need to be monitored during the steel strand tensioning process. The prestressed concrete lining is in full-section compression, and the longitudinal tensile stresses are lower than the limit that could control the cracking of lining concrete, indicating a reasonable tensioning process for steel strands.