| Summary: | The thesis aims to find the changes in design and execution to immersed tunnels in subarctic regions. The Orlovsky Tunnel in St. Petersburg serves as a case study. The Orlovsky tunnel is a 1600 m tunnel in a rapid flowing river. the ice regime of the Neva River is characterized by frazil ice, which causes hanging ice jams and anchor ice. Together with changes in the flow velocity profile in the frozen period, a more robust tunnel protection is required. Thermal expansion of ice, drift ice, and drag on an ice cover require a sloped embankment to reduce shear, which in turn increases the surcharge on the tunnel. Rubber gaskets such as the Gina and Omega profiles are researches and suggestions are given for rubber composition, and its effect on fatigue, watertightness, strength, and transport requirements. Thermal loading of the tunnel was also analyzed. It was concluded that the plastic hinge capacity of the corners was sufficient to resist the temperature differential in the outer sections of the tunnel. Cracking of the inner walls require extra horizontal reinforcement. Large temperature fluctuations may require alternate types of expansion joints or smaller tunnel elements. A probabilistic planning was finally performed to quantify the risk of non-completion in a single ice-free construction period. For this a Monte Carlo simulation was utilized. This had implication on the number of tunnel elements, foundation, the construction dock location, and so forth. Emergency measures, such as a frazil collector and ice boom are recommended in the case of early frost. Hydraulic Structures Hydraulic Engineering Civil Engineering and Geosciences
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