Research On The Treatment Technology Of Large Deformation Of Shallow Buried And Excavated Tunnel

Tunnel has greatly improve the traffic condition,improve the characteristics of the transport ability,has the important status in traffic network,but due to the explosive growth of traffic volume,the current domestic many early built tunnel tend to become a major disaster area of traffic congestion,can offer an alternative way to ease traffic pressure at present,there are new tunnel near the site of the new and the old tunnel in situ expansion,the latter in domestic successful case is less,the fundamental reason lies in the demolition process,and the expansion of the tunnel lining and surrounding rock interaction mechanism in the process of research.This dissertation relies on the in-situ expansion project of the left line of the New Songjiagou No.1Tunnel in Zhongliangshan Tunnel Group in Chongqing.Based on the existing engineering geological data and related design documents,the construction method of the left-line in-situ expansion project of the New Songjiagou No.1Tunnel is studied,and the treatment plan for the shallow-buried large deformation problem occurred during the in-situ expansion of the tunnel is analyzed.Through the finite element numerical analysis software MIDAS/NX,the numerical simulation of the proposed shallow-buried large deformation problem and the correlation analysis of the simulation results were carried out,and the theoretical analysis was carried out by comparing the results of the field monitoring measurement data with the numerical simulation results.The main research results are as follows:(1)Studying the expansion plan of the supporting engineering tunnel,a total of five scheme design,and finally combined with the environmental conditions of the project and comprehensive comparative analysis,the third design is the final design.At the same time,the construction plan of the left line of the new Songjiagou No.1 tunnel was analyzed.The two construction schemes were selected as follows: layer excavation method and the CD method excavation.Finally,after theoretical analysis and combined with engineering practice experience,the excavation construction plan of the new Songjiagou No.1 tunnel is determined as the CD method excavation.(2)Analysis of the causes of large deformation during the construction of the left line of the New Songjiagou No.1 Tunnel,the main reasons for the large deformation are: geological conditions,geostress(ground stress)and geological structure,construction methods,support conditions and so on.Meanwhile the problem of largedeformation during the construction of the left line of No.1 Tunnel in New Songjiagou was dealt with urgently,its main measures are support and reinforcement of the initial branch in the cave,and the ground cracks are closed by high-grade cement mortar,and cut-off channel are added outside the scope of the surface deformation.(3)Research on tunnel grouting reinforcement technology,mainly studies and analyzes the mechanism and function of radial grouting reinforcement,concurrently radial grouting reinforcement was carried out on the large deformation surrounding rock section during the construction of the left line of the New Songjiagou No.1 Tunnel.(4)After the large deformation problem of the tunnel is strengthened,the monitoring data of the tunnel during the excavation process are monitored and analyzed.Two representative sections are selected: ZK1+690 section and ZK1+678 section.The data of surface settlement,peripheral convergence,dome subsidence and temporary support structure are monitored and analyzed.Data analysis shows that after the reinforcement treat obtaining the large deformation problem caused by the tunnel,the monitoring data in the tunnel excavation process are normal,and meanwhile is little difference between the calculated data of each monitoring data model.