Analysis Of Shield Tunneling Cutting Tools Replacement On The Stability Of Surrounding Soil

Urban subway is booming in China at present, but the shield method inconstruction safety, the geological conditions of strong adaptability, the advantages offast speed, less interference of city gradually become urban underground railwaytunnel construction technique of choice. The cutter head is one of the key componentsof shield machine, when the shield machine tunneling distance is too long to tool wear,tool does not adapt to the formation, the need to change tool. Cutter tools replacement,repair and so on is indispensable to shield construction process. Since the limitation ofgeological conditions and construction process, the shield tunnel surrounding stratasuffered by the advance in the process of the influence of tool change is still can’tavoid, so the tool change during the process of shield tunneling effect on the stabilityof the surrounding strata has very important significance.Based on the engineering background of Hefei No.1subway line, the tool changein the process of shield tunneling on the influence of the soil around the theoryanalysis and numerical analysis. Mainly to the following conclusion:1. In Shenzhen metro shield tunneling tool change process based on in-situmonitoring data, verify the paper establish a three dimensional change cutters ofshield model rationality, can objectively reflect the shield originating in the process offormation stress, displacement variation of the truth.2. Change cutters of shield tunneling engineering in the soil with the increase ofthe longitudinal reinforcement range can significantly reduce the surface subsidence,horizontal soil consolidation effect on reducing surface subsidence effect.3. In view of the typical formation of Hefei, shield tool change during the processof the longitudinal reinforcement10meters, transverse reinforcement scope of12meters can make influence on soil in shield tunneling process meet the shield tunnelconstruction and acceptance standard GB50446-2008.4. The shield in blade surrounding strata subsidence maximum value appeared inthe tunnel lining arch top surface, maximum uplift in the tunnel lining with archbottom; For the tunnel roof with the increase of reinforcement length, making themaximum settlement of surrounding soils of shield gradually decreases, and thedecrease of the maximum uplift accordingly;5. As the reinforcing distance increasing, the scope of the corresponding surfacesubsidence shrunk, maximum subsidence value constantly decreases, and present asymmetrical shape of the cross-section of the tunnel, the same cross section above thetunnel axis surface settlement value maximum, the greater the distance nearer the axisof sedimentation value.6. Change the knife surface longitudinal impact scope of about12m (1.5to2times the hole diameter), transverse impact scope about20m (3-4times holediameter).