Investigation of Reasonable Prestressing Range of Water Transmission Shield Tunnel under High Internal Pressure Effect

Prestressed double-layer lining structure (pipe sheet outer lining-prestressed concrete inner lining) of shield tunnels is more and more widely used in water tunnel projects due to its good impermeability and stability. Under the high internal water pressure environment of water conveyance tunnels, the reasonable pre-stressing range of the prestressed lining is the key to the economy and safety of the project. Based on this, relying on the Pearl River Delta Water Resources Allocation Project, the ABAQUS three-dimensional finite element model of prestressed double-layer lining in water conveyance shield tunnel was established to analyze the variation rule of the structural mechanical properties of the double-layer lining under different prestress conditions, and to obtain a reasonable prestress range of the prestressing inner lining under the action of high internal water pressure. The results show that: The prestressed inner lining is affected by prestress, the deformation is larger than the outer lining of the pipe sheet, which makes the inner and outer lining contact surface in the upper semicircle 180° range and the position of the arch bottom lane in the open state; during the operation period, the double-layer lining contact surface is completely closed under the action of the internal water pressure. Under 68% design prestress, plastic deformation occurs at the location of prestressing liner anchorage groove, and the reasonable value range of prestressing liner tensioning prestress for shield water tunnel is 68% ~ 138% design prestress, and the results can provide a reference for the design of prestressing double-layer lining structure of shield tunnels.