Mechanical behavior of two kinds of prestressed composite linings: A case study of the Yellow River Crossing Tunnel in China

This paper presents the mechanical behavior of two innovative prestressed composite linings in shield tunnels for water conveyance. The Yellow River Crossing Tunnel of the Middle Route Project of the South-to-North Water Division Project (SNWD) is adopted in this study as a case. Three-dimensional finite element models are established to analyse the stress distribution and deformation feature of the prestressed composite lining when the tunnel is under the completed segment assembly condition (CSAC), the completed cable tension condition (CCTC) and the design water pressure condition (DWPC). The calculation and analysis results reveal that the prestressed composite lining with rebars (Model R) has an obviously combined bearing capacity, and the rebar is the key factor influencing the capacity. The prestressed composite lining with membranes (Model M) has a relatively separated bearing capacity, because the membrane can play a significant role in preventing stress transmission between the segmental ling and the secondary lining. Full circular compression can be realized for the secondary linings of both Model R and Model M when the tunnel is under the DWPC. However, the load bearing mechanism of Model M is more concise than that of Model R, the secondary lining of Model M is more secure than that of Model R because of the full use of prestresses and materials, and the membrane is beneficial to anti-seepage. By contrast, Model M is more suitable for the Yellow River Crossing Tunnel.