The Analysis Of Construction Monitoring And Stability Of Large Section Tunnel With Shallow Buried Excavation Method In Loess Area

The construction of subway have been in many major cities included in theconstruction and planning in China，its development trend toward a high，big，wide，shallow the direction of development，compared with the small section tunnel，shallow-buried excavation tunnel of large cross section was in many ways a newimproved and requirements. Facing the complexity of the engineering geologicalconditions，adjacent buildings and complex underground pipeline always brings highrisk in the urban construction of large cross section tunnel，all these great challengs arebrought for construction and monitoring.How to control the deformation of the strataand the lining and make effective coping scheme after the deformation is thedevelopment of underground engineering problem to be solved in the tunnelconstruction process，to protect the tunnel nearby buildings，underground pipelines androad traffic safety. The interval Shallow-buried excavation Tunnel of large section inloess region have been studied by author rely on the first phase of Harbin subwayproject，which the Shallow section tunnel of10th tender Hanan Station to Academy ofstation，is constructed in this paper，The main research contents include:1、This paper predicts and summarizes the characteristics of the loess tunneldeformation and fracture surface and controls the various measures of deformation andfracture，it develops a Monitoring scheme and verifies its fessibility，which is suitablefor construction site. Moreover， the optimized idea of monitoring scheme ofconstruction site and construction experience is discussed.2、Through collating and analyzing the field monitoring data results，it obtains the changing rules of surface settlement，vault settlement and horizontal convergence andthe interaction and the influence relation between uplink and downlink. The surfacesettlement accords with the common settlement rules，the change rule of vaultsettlement and surface settlement is consistent，and they increase with the increase ofsurface settlement，the change of horizontal convergence in tunnel excavation is notobvious，and the surface settlement of downlink is greater than the uplink.3、This paper，Using the finite element software，has three dimensional numericalsimulation analysis of large sections tunnel construction process， and studiesdisplacement and stress change rules of soil and primary support in the excavationprocess. Horizontal displacement in the arch waist and arch feet of the tunnel isbigger， vertical displacement in vaults and arch is bigger，vaults，arched bottom，arch waist and arch feet are the stress concentration area of the tunnel，which are alsothe key monitoring site and support area in the construction process.4、This paper，summarizes the water leakage of the field loess tunnel，analysis thecauses of the four arc tunnel water leakage，and puts forward suggestions andCountermeasures for the four arch tunnel safety，combined with field monitoring data.