The Influence of the Variable Thickness of Prestressed Linings with Annular Anchors on its Mechanical Properties

Abstract

By embedding annular anchors, prestressed linings with annular anchors provide active prestress, which can effectively resist the high internal water pressure in large-diameter hydraulic tunnels. The variable thickness of concrete liners along the circumference can significantly influence the mechanical properties of the lining. On the basis of the prestressed lining of a 6.8-m-diameter pressure tunnel in the Yinsong Diversion Project, we adopted a 3D numerical modeling method to study the influence of the average and local thicknesses of the lining on its mechanical properties. The results show that the prestress of the lining used in resisting the internal water pressure is ultimately derived from tensioning the annular anchors. The average thickness of the lining has little effect on its load-bearing capacity. In elliptical lining, an annulus of a slight tensile stress area appeared on the inner side of the lining, whereas the crown and invert sections will form the weak area because of structural bending moments.