Study On Rock Cover Of Subsea Tunnel In Jointed Rock Mass

The depth of subsea tunnel rock cover plays an important role in the design of subsea tunnel. The design of subsea tunnel must take safety factor and economy factor into consideration during its construction and usage period. How to determine reasonable subsea tunnel rock cover thickness is still an intractable research subject. At the same time, the spot observations and geological statistical data show that there are different-sized joints and deficiencies in rock mass. Their impair and damage affect the distinction of the deforming and the impair breakage in the adjacent rock of underground engineering. The fractures distributing and the seepage flow in rock mass has large influence on the stability and the rock cover thickness of subsea tunnel. The paper studied these problems mentioned above on the basis of NingBo XiangShan subsea tunnel project.The preliminary thickness of the subsea tunnel rock cover was determined through using project analogy method. Comparison was drawn between NingBo subsea tunnel and other subsea tunnels according to their analogous condition, for example the ocean water depth, thickness of overburden layers and properties of rocks. And the design's feasibility made in conceptual phase was studied.The program of finite elements based on the theory on impairs and damages simulates the NingBo XiangShan subsea tunnel project. The location of soleplate line and the thickness the minimum rock cover are further studied through numerical simulation. The minimum thickness of rock cover is brought forth according the result of numerical simulation.Taking the seepage flow of rock mass into account, the fluid-mechanical interaction model of FLAC3D is applied to simulating the NingBo XiangShan subsea tunnel project. The affection of the seepage flow on the stability and the rock cover thickness of the NingBo XiangShan subsea tunnel project is researched.