Elastoplastic Analysis of Surrounding Rocks of Submarine Tunnel with Consideration of Seepage: Fid-Bau Portal

Elastoplastic Analysis of Surrounding Rocks of Submarine Tunnel with Consideration of Seepage

Wang, You / Wang, Xing-hua / Chen, Jun-ru

Based on the twin shear unified strength theory, the analytical equations for calculating stress, displacement, radius of plastic zone, and characteristic curve equation of surrounding rock in circular submarine tunnels were proposed under the condition of fluid-solid coupling. As the tunnel is usually located under high water pressure, the effective stress of surrounding rock will be reduced for high pore water pressure and seepage pressure according to the calculation results. This may bring about the arch formation and lower stability of strata. Moreover, intermediate principal stress has a certain influence on the stress, displacement, and radius of the plastic zone of surrounding rock. Hence, it is necessary that seepage and intermediate principal stress are rationally considered in the surrounding rock stability analysis and the lining structure design of submarine tunnels because this is beneficial for maximizing the strength of the surrounding rock. Selecting reasonable strength criterion of rock is the basis for correct analysis in rock mechanics and engineering. The results of this study may be applicable to actual situations in various engineering fields by choosing different coefficients of intermediate principal stress $b$ and effective pore water pressure coefficient $η$ . Further, these may provide a theoretical base and practical value for distinguishing the stability of surrounding rock; designing supporting structure and determining the area of pre-grouting submarine tunnels.