| Due to the complexity of geological conditions, rockburst, large deformation and large area collapse in the process of tunneling, surface subsidence and other geological and engineering disasters frequently occur, which result in casualties, equipment loss, duration delays and engineering failures. In the tunnel construction, geological disasters are formed under various complex conditions and studying the stress field and seepage field of the surrounding rock of the tunnel can help to understand the geological disasters. Based on the introduction of the basic theory of seepage in fractured rock mass, this paper summarizes the coupling effect of seepage field and stress field in fractured rock mass. Then, the variation law of seepage field and stress field before and after tunnel excavation is analyzed, and the influence of groundwater level and grouting thickness on seepage stress is studied. Then, the variation law of seepage field and stress field before and after tunnel excavation is analyzed,and the influence of groundwater level and grouting thickness on seepage stress is studied.Finally, the variation law of stress field and seepage field with tunnel excavation time is studied with practical engineering. This paper mainly draws the following conclusions:(1) The excavation of the tunnel leads to the seepage of the groundwater in the tunnel, and the seepage field changes greatly. Pore water pressure distribution area is produced around the tunnel-surrounding. After tunnel excavation, the percolation velocity of tunnel is relatively large,which is not conducive to the stability of surrounding rock. After grouting around the tunnel,the pore water pressure of the tunnel is recovered, the seepage velocity is greatly reduced, and the grouting effect is very obvious.(2) Tunnel excavation caused significant unloading effect of the rock, causing different levels of low stress area around the tunnel, in which the stress in the vault and the arch bottom is the largest. The overall stress of the surrounding rock after grouting is improved, but the stress concentration is easy at the interface between the grouting circle and the surrounding rock.(3) The groundwater level and the different thickness of the grouting circle will have a great influence on the seepage field and stress field in the surrounding rock. The influence of groundwater level on the seepage field is mainly in the numerical value. The higher the groundwater level is, the higher the seepage is around the tunnel, but the distribution of seepage field in different groundwater levels is very similar. The seepage rate of the surrounding rock can improve the seepage velocity in the surrounding rock, and the seepage field of the surrounding rock is obviously improved with the increase of the thickness of the grouting circle. The higher the groundwater level, the greater the effect on the stress field. The greater the thickness of the grouting ring, the more favorable the protection of the stability of the surrounding rock.(4) The numerical simulation of the Jiaoxi River tunnel is carried out to verify the correctness of the numerical calculation of the two-dimensional model. At the same time, the changes of seepage field and stress field with excavation time are analyzed, and the law of pore water pressure, velocity and deformation is obtained. |
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