Study On The Stability Sorrounding Rock And Slope Around Xiaoling Tunnel Export

The construction of tunnel is difficult to avoid geological disasters landslides, avalanches, bias, landslides and avalanches, landslides are the most common geological disasters.Tunnel entrance is the first construction of tunnel construction, as the safe of tunnel entrance relate the entrance to tunnel and safe construction. In this paper, combined with the actual situation of the Xiaoling tunnel entrance,through investigation and analysis, field monitoring, numerical simulation tools and other means to study the surrounding rock stress distribution and the slope deformation and destruction regular patterns; It summarizes the basic factors affecting the surrounding rock and slope stability; It comes to the deformation characteristic of surrounding rocks and failure modes of slope; It analyzes the surrounding rock and slope stability of tunnel entrance. The main research work of this dissertation is as follow:①Through analyzing geological conditions at exit of Xiaoling tunnel,exit section’s natural slope was obtained to be integral satble.On the contrary, poor stability in exit section’s artificial front slope.According to this analysis,main factors which effect surrounding rocks at exit section and slope stability of Xiaoling tunnel included: topography and geomorphology,rock behaviour,rock mass structure,atmospheric rainfall and so on.②Through researching on the deformation characteristic of surrounding rocks on tunnel entrance and failure modes of slope, the failure types of surrounding rocks mainly are local fall-stone failure,structural failure and deliquescence failure. According to this research, the failue models of slope on Xiaoling tunnel entrance included: plane failue and partial slump failue.③This paper calculated the surrounding rock pressure and safety factor of surrounding rock by establish the mechanical model of shallow tunnel. The stability analysis methods of slope on Xiaoling tunnel entrance is Janbu method. Selecting simplify Janbu to analysis the stablity of tunnel entrance slope and building a calculation model based on real situation to conclusion that the possibility of landslide on tunnel exit section is existent with continuous rainfall condition.④Using FLAC3 D to analyze the stability of the Xiaoling tunnel entrance slope.It also obtains the corresponding stress characteristics,displacement characteristics and stability situation. Simulation results show that the stability of surrounding rocks and slopes under natural state and excavation state, it obtains the corresponding stress characteristics,displacement characteristics and stability situation.The simulation results show that entrance excavation of the shallow tunnel cause a greater surface subsidence on surface rock and soil mass nearby tunnel axis.Surface subsidence of right tunnel export is greater than which on the left,and reaches the maximum at the distance of 2B~2.5B(hole diameter),leading to roof fall, collapse and other accidents at the part of vault.⑤The deformation characteristic of surrounding rock on the Xiaoling tunnel was studied by monitoring and theoretical analysis. The time effect and space effect will be further explained. The deformation of surrounding rock was monitored and analyzed. And the deformation characteristics of the Xiaoling tunnel surrounding rock were obtained.