Abstract
Aiming at the high internal and external water pressure tunnels built in unfavorable geological bodies, this study proposes a novel type of composite support structure in which steel plates are poured inside concrete linings. Compared with traditional structures, it has the advantages of higher tensile strength, better crack resistance, and impermeability. Taking the diversion tunnel of a hydropower station as an example, based on linear and non-linear finite element simulations, mechanical properties of the steelconcrete composite lining structure for a hydraulic tunnel in soft surrounding rocks are analyzed. On this basis, the concrete crack control under this supporting condition is verified. Research results can provide a reference for the selection of reasonable steel plate thicknesses and reinforcement types in design.
Highlights
Hydraulic tunnels generally adopt a composite lining structure, with rock bolts and sprayed concrete as the initial flexible support, and reinforced concrete as the secondary rigid lining [1]
Composite structures of steel plate and concrete is a new type of tunnel lining structure, which has the characteristics of excellent tensile performance of steel plates, and high compressive strength of concrete [2]
Due to the extremely poor geological conditions of the tunnel and high-water pressures, considering the safety and cost of the project, the tunnel adopts a new type of lining with steel plates placed in the middle of reinforced concrete linings
Summary
Hydraulic tunnels generally adopt a composite lining structure, with rock bolts and sprayed concrete as the initial flexible support, and reinforced concrete as the secondary rigid lining [1]. The traditional reinforced concrete lining has the defects of large thickness, complicated process, and poor crack resistance, so it is prone to cracking, water leakage, and other diseases in long-term operation. The pressure diversion tunnel has a flow rate of 178.92m3/s, which connects to the upstream surge tank through a turn on the plane. Due to the extremely poor geological conditions of the tunnel and high-water pressures, considering the safety and cost of the project, the tunnel adopts a new type of lining with steel plates placed in the middle of reinforced concrete linings. Using linear and non-linear finite element simulation methods, this study takes the diversion tunnel as an example, the mechanical properties of steel-concrete composite lining structures under the conditions of high internal-external water pressures in soft rocks are comparatively analysed. A reasonable plate thickness and reinforcement type for design selection are put forward
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