Research On Parameter Sensitivity Of Tunnel Crossing Fault Fracture Zone And Advance Grouting Reinforcement

Based on the Tianheshan tunnel as the engineering background,this paper analyzes the sensitivity of the broken zone parameters,and conducts in-depth research on the advance grouting reinforcement measures.By studying the parameter sensitivity of the fault fracture zone and the multi-level influence law of a single factor,the parameter sensitivity ranking of the fault fracture zone is obtained,and the grouting parameters are specifically improved according to the sensitivity ranking to improve the advance grouting reinforcement.effectiveness.Under the condition of advanced grouting reinforcement,the changes of the vault settlement,the longitudinal deformation of the tunnel section and the vertical surrounding rock pressure of the vault with the excavation are studied,and the longitudinal overlap length and grouting thickness of the advanced grouting reinforcement are analyzed for reinforcement Effect of effect.Through literature analysis,engineering case analysis,numerical simulation,on-site monitoring,summary and other analysis methods,some conclusions and suggestions with engineering application value were obtained.The main research contents and conclusions are as follows:(1)Through numerical simulation of tunnel excavation through the fault fracture zone,7 parameters were selected for orthogonal experiment analysis,and the sensitivity of the vertical wall rock pressure of the vault was ranked as normal wall rock grade(A)>Poisson fault Ratio(F)> fault elastic modulus(E);through the above numerical simulation orthogonal test,it is concluded that the sensitivity of the vault settlement is ranked as normal surrounding rock grade(A))> fault elastic modulus(E);(2)In the single-factor multi-level analysis,taking the vertical surrounding rock pressure of the vault of the tunnel and the vault settlement as the main analysis parameters,it is concluded that 100 MPa to 1GPa is the main influence interval of the elastic modulus of the fault;10°?16° is the fault The main influence interval of friction angle;0KPa?100KPa is the main influence interval of fault cohesion;as the water pressure of the fault continues to increase,the vertical surrounding rock pressure of the vault and the vault settlement gradually increase,and the overall change trend is close to linear Change;and under the conditions of the deep-buried tunnel in this paper,the severity of the fault fracture zone has no effect on the vertical surrounding rock pressure and vault settlement of the vault;(3)Under the condition of advanced grouting reinforcement,the impact range of the crushing zone on the vault settlement,the longitudinal deformation of the tunnel section and the vertical surrounding rock pressure of the vault is approximately 10 m away from the fault crushing zone;The change rule of the index is as follows: the settlement of the vault is accelerating and the settlement of the vault tends to be stable after the excavated palm face passes through the monitoring section for 2m;the longitudinal deformation of the tunnel section is accelerated,and the longitudinal deformation after the excavation palm face passes the monitoring section cannot be monitored,The value suddenly changes to 0mm;the vertical surrounding rock pressure of the vault accelerates to increase until the palm face is excavated to 1m after the monitoring section is the largest,and the stress relief of the surrounding rock is completed after the palm face passes through the monitoring section 2m,and then the arch The vertical surrounding rock pressure increases slowly with the excavation,until the excavated palm face stabilizes after passing through the monitoring section for 10m;(4)With the decrease of the longitudinal lap length,the settlement of the vault increases linearly,and the extrusion deformation of the palm face increases;when the longitudinal lap length is 2m,the sudden deformation of the palm face extrusion increases to-88.3mm,so in order to ensure construction safety,the length of longitudinal overlap should not be less than 2m within the scope of this paper;(5)The greater the grouting thickness,the greater the distance between the plastic zone in front of the tunnel vault and the palm face,and the plastic zone in the fracture zone,the smaller the settlement of the vault and the extrusion deformation of the palm face,the more the construction For safety;therefore,considering the safety of construction and economic benefits,the thickness of grouting is recommended to be not less than 1.5m.