Study On Mechanical Behavior Of Rock For Subsea Tunnelling

Based on the Xiang'an subsea tunnel engineering in Xiamen, The paper studies the ground deformation problem during the excavating process of the engineering in the soft surrounding rock.Three construction scheme has been simulated numerically by the nonlinear finite element method calculation and presented the rule of the field of displacement distributing and movement and the key-points of controlling ground settlement for the large section low net-distance and shallow tunnel under the condition of class V surrounding-rock of CRD ,dual side wall and top and bottom benching method comparatively. The results of simulation were compared with that of measurement and have guiding significance for tunnel design and construction.Using fast lagrangian analysis of continua in three dimensions(FLAC^3D) method, Three-dimensional analysis for 80m length has been done,from YK6＋880,along the longitudinal of the tunnel to determine the region that rock stress and displacement largely changes and present the situation of the supporting structure in construction process, the result can be identified in the support and the scope of advance support and provide a reasonable reference for the design and construction.Because of the tunnel threatened by both on the water body and groundwater under the influence, it runs through the handling of water in the entire process of construction. Pressure of the surrounding rock can be reduced by supporting role in the structure of itself strata arch, but hydrostatic pressure load which directly press on the lining is not affected by any arching role to reduce.The seepage analysis for the F4 weathered deep trough was carried out by the finite differences software FLAC^3D in the fourth chapter to determine the pore water pressure field after the seepage stability and the distribution of excess pore water pressure field due to deformation caused by excavating the tunnel, providing a reference for the design about water load.Through a large number of monitoring data, the dissertation further expounded on the trend of changes in mechanical behavior and distribution law of the rock at the construction phase.