Abstract:

Based on the seepage finite element method and rock strength reduction theory, considering sea water seepage， study the coupled fluid-mechanical analysis method for subsea tunnel in which the fracture zone exists, and we apply this method to a subsea tunnel for the seepage distribution analysis and tunnel seepage stability analysis. The results show that sea water infiltration induced the obvious increase of water head, seepage flux and seepage gradient in surrounding rock，especially in the fracture zone, which makes the safety factor of tunnel decrease obviously. On the condition of reinforce treatment, the whole safety of tunnel has increased, and the seepage flux decreased, but the seepage gradient in treatment position increased obviously. So, it is necessary to improve the supporting strength in the treatment position. According to these conclusions, the paper discussed the design and support of subsea tunnel considering the seepage pressure and gradient.

Key words: subsea tunnel, seepage finite element, strength reduction method, seepage pressure