Study On Stability Of Tunnel Anchorage With Weak Interlayer Under Periodic Change Of Reservoir Water Level

Based on the tunnel anchorage project of Changling Bank(North Shore)of Shuibuya Qingjiang Bridge,this paper combines theoretical analysis and numerical simulation to study the influence of reservoir water level variation on tunnel anchor stability.Firstly,it is elaborated in the status quo of research at home and abroad.The research status of tunnel anchor research,the research status of reservoir water bank slope and tunnel anchor and the current research status of seepage stress coupling are summarized and summarized.The research method of this paper;then introduces the basic theory of seepage and the solution of the bank slope saturation line based on the Dupuit hypothesis and the Boussinesq hypothesis,and the three-dimensional modeling of the tunnel anchor based on the experience of establishing the tunnel anchor model.Suggestions were made.Using the SEEP/W module in GeoStudio software,a two-dimensional bank slope model was established to simulate the change process of the groundwater saturation line on the bank slope at various time intervals of the reservoir water level change.Finally,on the calculation of the GeoStudio software,Based on the seepage-stress-slope type in Midas GTS,a three-dimensional model is established,and the influence of reservoir water level change on the tunnel anchor structure and the displacement field and stress field of the bank slope is simulated.According to the above research contents and methods,the following conclusions were obtained:(1)The change of reservoir water level has a significant impact on the groundwater saturation line of the bank slope.In the rising stage of the water level and the high water level,since the height of the immersion line inside the bank slope is lower than the height of the reservoir water level,the height of the immersion line is continuously increased,and the immersion line is bent upwards until the immersion line rises to the same level as the reservoir water level;During the descending phase and the dry water level,due to the lag of the groundwater immersion line,the internal immersion line height of the slope is higher than the reservoir water level,so the immersion line height decreases continuously,and the immersion line is bent downwards until the immersion line drops to the reservoir level.same.(2)The change of reservoir water level has a great influence on the displacement of tunnel anchor.During the rising water level,the horizontal displacement level of the tunnel anchor changes to the left and vertically upwards.The horizontal left shift reaches the maximum after the water level rises,and moves to the left relative to the initial time level by 0.33 mm.In the high water level stage,the tunnel anchor displacement horizontal direction The right and vertical upward changes,the vertical upward displacement reaches the maximum at the end of the high water level phase,and moves vertically upwards by 2.06 mm with respect to the initial moment;when the water level decreases,the tunnel anchor displacement level changes to the right and vertically downwards,horizontally.To the right,the maximum value reaches the maximum at the end of the water level lowering stage,and is 0.11 mm to the right relative to the initial time level.In the dry water level stage,the tunnel anchor displacement level changes to the right and vertically downwards,and the displacement gradually returns to the initial moment.(3)The periodic variation of reservoir water level has greater influence on S-XX and S-YY stresses of tunnel anchors,but less on VON MISES stresses.