| Because of the limitation of special underground environment in cities, underground overlapped tunnel arises more and more to meet the increasing demand of underground transportation in cities. Due to the flexible form of mining method to build overlapped tunnel, it is more suitable for cities which have many municipal engineering projects and pile foundations of tall buildings. Its economic and social benefits are obvious.Based on the overlapped tunnel by mining method of ShaYan inter-val of GuangZhou-FoShan intercity rail transit, mechanical behavior and deformation rule of surrounding rock of overlappped tunnel was studied through FEM simulation analysis combined with the monitoring measurement. The main contents include:(1) Using finite element analysis software MIDAS-GTS, the construction stage with2D FEM method was analyzed. The influence on stratum deformation, mechanical properties of tunnel lining and adjacent tunnel caused by surrounding rock stress release was studied. The reasonable construction sequence under the specific geological conditions was chosen.(2) Based on the2D analysis conclusion, the construction stage was analyzed with3D FEM, the special mechanical behavior of construction of overlapped tunnel by mining method was discussed, and the relevant rule and key control technique was also studied.(3)The influence on overlapped tunnel construction by advanced small pipe pre-reinforcement was simulated and analyzed.(4)Monitoring data was analyzed, comparison between the monitoring data and numerical simulation data was made. |
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