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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. [ABSTRACT FROM AUTHOR]

Riverine wetlands provide important habitats and travel corridors for resident and transient species, playing a key role in maintaining the diversity of entire landscapes. This paper assessed a long-term (1990–2013) landscape changes and avifauna community dynamics in the Yellow River wetland natural reserves, China. Remote sensing information was combined with field surveys to collect critical data on land use and avifaunal populations. The results reveal that land use has dramatic changes during 1990–2013. Utilized water features have significantly decreased over 20 years, whereas artificial land features such as paddy, dry field and built-up area have shown a steady increasing trend in the three riverine wetlands. The spatial landscape patterns of the three wetlands have become fragmented and notably heterogeneous as results of rapid economic development. With the changes of utilized water features, avifauna data show that some overwintering and transient species are becoming permanent residents. Though there is an abundant and diverse array of bird species utilizing the wetlands, migrating traits of these avifauna species have changed. This study can provide basic information for making effective and sustainable conservation plans for the entire Yellow River wetland natural reserves. [ABSTRACT FROM AUTHOR]