Study On Deformation Control Measures Of Single-track Railway Tunnel With Squeezing Rock In High Intensity Area

Taking Lixiang single-track railway tunnel as the research background,the geological structure in this area is complex,the new structure is strong,the scale of active faults is large,seismic activity is frequent,the magnitude is large,the seismic fracture zone is long,and the dislocation is large,which is a high-reatence seismic area.The lithology of the entire tunnel of the Lixiang Railway is weak surrounding rock,and due to extrusion,there is a large deformation.On the one hand,the main problems encountered in the tunnel are the influence of high-facing seismic areas,and on the other hand,due to the highland stress,the surrounding rock has extrusion deformation,which brings great difficulties to construction.For general tunnels,tunnel structure design is characterized by surrounding rock classification,and extrusion surrounding rock tunnels are gradually no longer applicable by using the surrounding rock classification method due to extrusion deformation,but more according to deformation grade.This paper is based on the previous research on deformation grade,taking Lixiang single-track railway tunnel as the engineering background,and carrying out research on different deformation level control measures by on-site investigation,numerical simulation and field test.(1)Research on extrusion surrounding rock cross-section based on deformation classification.By increasing the curvature of the border wall,different section types are established.Three working conditions are designed under each deformation level,and the load structure method is used to calculate.The Ia(minimum curvature radius of 1000 mm),IIa(minimum curvature radius 2000 mm)and IIIa(lowest curvature radius 3800 mm)sections are the best in structural stability through the structural safety factor and the internal force of the structure.(2)Research on seismic measures based on deformation classification in high intensity areas.The grouting reinforcement and deformation seams of seismic countermeasures are studied,and numerical simulation is used to consider facilitating the construction site and considering the cost.Combined with the calculation results,the recommended value is given.The deformation seam spacing at different deformation levels is 12 m,and grouting reinforcement is taken at stages I,II and III deformation grade respectively.Use the thickness of 3 m,6 m and 6 m.(3)Research on construction control measures based on deformation classification.The construction method and grouting reinforcement are optimized under different deformation levels.Through numerical simulation results,it is concluded that the I,II and III stages of deformations adopt the full-section method,the two-step method(synchronous excavation of the lower step and the elevation arch)and the two-step method respectively,which can achieve the effect of controlling deformation.The calculation results of grouting reinforcement show that the thickness of the deformation reinforcement rings I,II and III are 3 m,6 m and 6 m,which is consistent with the calculation results of the thickness of the seismic reinforcement ring.(4)In order to verify the effectiveness of the numerical simulation,through the installation of the field components,the corresponding sections in the test section are monitored and measured,the safety and reliability of the numerical simulation are verified to ensure the safe construction of the project.