The Stability Analysis Of Surrounding Rock And Slope Of Da Qian Shi Ling Tunnel Porta

Found in the construction of large tunnel entrance before Shiling Tian Huan railway in the mountain surface is covered with thick layers of a large number of rock,loose rock mountain structure of great influence on the construction of tunnel entrance,serious problems of Railway Engineering construction.Under the premise of ensuring the safety of construction and reasonable control of the time limit,the purpose of reasonable savings is achieved.It is necessary to analyze the stability of surrounding rock of tunnel at the entrance of rock mass tunnel and study the construction method of relativity.In view of the typical problems faced in the construction of large tunnel in front of Shiling tunnel,the following aspects are studied in this paper:(1)based on the area of tunnel rock pile engineering geological conditions for research,access to relevant engineering data,fully grasp the characteristics of the geological environment of the study area,to provide sufficient information for the geological background.Put forward reasonable construction plan for this area.It is not suitable to adopt the method of partial excavation for the excavation of the tunnel portal of the former Shiling tunnel.The method of step is adopted,and it is suggested that a large pipe shed or an advance grouting small pipe be adopted as the pre support to ensure the safety of the construction.(2)according to the field monitoring data of the former Shiling tunnel portal,the variation of vault settlement,horizontal convergence,and surrounding rock stress of typical section DK69+279 are studied.Through monitoring the pressure of surrounding rock of tunnel,the steel stress,show that the construction of large section of the former Shiling import step excavation,advanced small pipe grouting reinforcement,and its application to the two lining do very good effect on the stability of surrounding rock in tunnel entrance from the former Shiling(3)a series of studies are made on the stability of the surrounding rock and its location in the entrance of the tunnel.The curve formed by the partial deflection can effectively avoid the small angle turning and the larger fluctuation between adjacent points.The multi-scale discrete wavelet denoising can be used to eliminate the error due to the insufficient number of cycles and the sparse interpolation points,so that it is more practical.The rationality and feasibility of the construction plan have been fully verified.(4)carry on the stability analysis and research of the surrounding rock under the engineering example of the big Shiling tunnel entrance section.Based on the discrete element theory,the numerical simulation of the tunnel under different excavation conditions is carried out by using UDEC software.The stability analysis of the surrounding rock of the former Shiling tunnel is carried out,and the deformation and stress law is found.The results obtained by numerical simulation are in good agreement with field monitoring and comprehensive analysis.The deformation law of surrounding rock is basically consistent.It shows that under the existing surrounding rock support,the tunnel has no instability phenomenon.The research content of this paper can provide certain reference value for tunnel construction research under similar geological conditions.