Analysis Of Composite Strata On Force And Deformation Of Shield Tunnel Lining Segment Structure In Shenzhen

This article relying on Shenzhen metro line11Chegongmiao station-Hongshuwan station and Nanshan station-Qianhaiwan station as engineering background, first selecting the typical section of bedrock protrusions and uneven soft geological conditions to simulate and analyze the influence of different conditions on the segment force deformation; Then selecting the test section and used fiber Bragg grating technology to segment surface and bolt for field monitoring, on the basis of analysis of the stress of the segment and bolt deformation; Finally comparing the numerical simulation results and field monitoring data.The main achievements and conclusions of paper are as follows:(1) Selecting typical sections with bedrock protrusions, respectively consider five kinds of bedrock protrusions width of0m,2m,4m,6m and8m working condition of segment stress deformation numerical simulation. The analysis results show that the influence of bedrock protrusions to segment differential settlement is significant; The bigger width of the bedrock protrusions, the greater the influence, the more obvious uneven settlement of segments, stress of segment of in contact with the bedrock protrusions or bedrock protrusions is more adverse. Because of the low tensile strength of concrete segment, with the increasing of width of bedrock protrusions, the risk of cracking of segment is increasing, thus taking segment tensile failure and the settlement difference between the corresponding section of the tunnel and the bedrock protrusions of the width of the product and40loop length (60m) ratio as a bedrock protrusions caused alarm value of the longitudinal uneven settlement. According to the result of calculation, considerring certain safe stock, the alert value option is0.3%o.(2) Selecting soft hard formation as typical sections, respectively considering five kinds of hard rock intruding into tunnel0m,1.75m,3.5m,5.25m and7m as the working condition of analysis of the segment of the stress and deformation, the results showed that the more hard rock intrusion excavation face, the more beneficial to the stress of the segment, but will increase the difficulty of the tunnel construction.(3) The fiber Bragg grating sensor is used for deformation monitoring of bolts and shield segments.Through the field monitoring data analysis, influence on the axial stress of bolt grouting pressure is bigger than cylinder thrust, segment after the emergence of shield shell, and the axial stress of bolt will be increased dramatically, increase significantly; Because of the effect of grouting pressure hysteresis, after excavating7piece (10.5m) with loop slurry solidifying, bolt stress leveled off. In the process of excavation, the ring to the axial stress of bolt is bigger than the longitudinal bolts, rings to be near bolts of cylinder bolt than far away from the oil cylinder bolt axial stress is big, but has enough safety reserve.Monitoring data show that all the maximum of bolt axial stress was345.46MPa,53.98%of bolt yield stress640MPa, showed that the bolt stress in a safe state.(4) Through the difference in weathered strata segment stress deformation analysis of numerical simulation, field monitoring bolt in the most unfavorable position of the stress, illustrates the rationality of the specified monitoring programme., in the process of tunnel excavation of shield construction7rings (10.5m) for monitoring the fault effect obviously, and the seven slices with loop displacement deformation is large, then decreases, finally leveled off. Same with the field monitoring data, shield tunneling when longitudinal bolts are mainly composed of axial tensile stress; In addition, the wall has a great influence on grouting for the bolt stress.