3D Finite Element Analysis Of TBM Water Diversion Tunnel Segment Coupling Seepage Field

Thanks to its advantages such as high mechanization, fast construction speed, small interference and high security, the TBM excavation technology becomes the first choice for the water diversion tunnel with long-distance and deep burial depth. Most current studies about tunnel did not consider groundwater pressure, or simplified it using "water-rock split" approach and exerted the pressure on the border of lining structure. Meanwhile, these studies failed to fully consider the phenomenon of leakage, which occurs mainly in segment joints. Additionally, geological models in studies were simplified to different extent, mostly were simplified as homogeneous body. Considering above deficiencies, the 3D finite element analysis of TBM water diversion tunnel coupling seepage field is analyzed, and obtained the researching result as follow:(1) Contraposing the disadvantage that many studies simplify the tunnel surrounding rock as homogeneous body, the 3D geological model is established. The geologic modeling theories such data structures, geologic modeling technologies et al. are introduced firstly. And basing on geologic modeling theory, the 3D geological model of TBM water diversion tunnel was established using Visual Geo software, combining engineering example, providing the seepage simulation and tunnel stability analysis a geological model closer to engineering practices.(2) According to the engineering characteristic of TBM water diversion tunnel, the seepage field of tunnel surrounding rock considering leakage in segment joints is simulated. And the water pressure is applied on the structural analysis model as body force. The seepage field of the tunnel surrounding rocks was simulated based on the geological model, in which the engineering practice that deep-lying TBM water diversion tunnels bear large groundwater pressure and leakage tends to occur in segment joints was considered. After that, the scripts are developed to solve data transfer problem between the two nonmatching grids of seepage model and stress model, realizing the TBM water diversion tunnel stability analysis coupling groundwater pressure as body force, which takes the leakage in segment joints into consideration. In the 3D structural analysis result, the distribution of axial force and bending moment distributions are obtained through integration along stress path.(3) The sensitivity of tunnel surrounding rock parameters to the stability evaluation index was analyzed by introducing the sensitivity analysis method basing on the orthogonal experimental design. The sensitivity analysis method basing on orthogonal experimental design was introduced into the seepage stress coupling analysis model, and the tunnel stability evaluation index such maximum tension stress, maximum compression stress, maximum radial displacement of tunnel lining were obtained using 3D finite element method with different values assigning to the factors. The sensitivities of tunnel stability to the six above factors were analyzed with the range analysis method, providing guidance to the similar engineering.