STUDY ON STRESS CHARACTERISTICS OF SUPPORT STRUCTURE AND ITS INFLUENCING FACTORS OF SUBSEA TUNNEL

摘要

Excavating a tunnel in the saturated soil layer, the physics mechanical parameters of soil around the tunnel will be changed, and seepage force will be brought in the stratum, which may affect the stress and displacement of soil. To the underwater shallow tunnel with high water pressure, support structure must endure high water pressure except the wall rock pressure, which is very different from the hypothetic boundary condition of classical tunnel elastic and plastic solution. The lining structure stress character is affected by many factors such as the shearing strength in the interface between wall and lining structure, the thickness of rock cover, the depth of water, lateral coefficient of earth pressure, the stiffness and thickness of lining structure, et al. With considering these factors, the lining structure stress character was studied by use of program FLAC3D, and some useful conclusions are achieved, as follow: (1) The shearing strength in the interface between wall and lining structure has an important influence on the lining structure stress characters, the importance of composite lining waterproof flashing is introduced in the prevention for the craze of second lining; (2) Lining structure stress augment with the addition of the thickness of rock cover; (3) Water pressure can rapidly augment the lining axes stress, but has no influence on the lining bend moment stress; (4) Finally, the lining stress of Xiamen Xiang'an subsea tunnel are analyzed by use of FLAC3D program, which has a good use for the design and construction of this project.