| In recent years,due to the accelerated development of the city,the increase of urban population and the shortage of land supply,the utilization of underground space has become increasingly prominent.The new tubular roof method is well known for its good control of formation deformation,no influence on ground traffic,high construction safety,environmental friendliness and so on.Many urban shallow projects are strictly required for deformation control.Therefore,the application of the new tubular roof method to the construction of underground shallow buried engineering has become a new trend.This article is based on the project of the railway station tunnel under the Yingze street in Taiyuan.For the high compressive and low intensity new loess strata,the new tubular roof method is adopted for the super shallow buried underground passage with deep buried depth of 3.5m.The corresponding numerical simulation is carried out for the surface settlement caused by steel pipe jacking,steel pipe cutting and pipe support,and the stress and deformation of surrounding buildings.The main research work and research results are as follows:(1)the analysis of settlement control standards for railway and existing buildings,analysis of deformation control technology,analysis and prediction of surface subsidence during construction.Under the most unfavorable conditions,The allowable surface subsidence value of the railway line is 12.0mm,The surface of platform canopy allowed sedimentation value was 35.3mm,Ground parcel channel allows settlement value is 33.5mm.(2)Determine the position of the steel pipe,the parameters of the layout of the steel tube and the design of the connection.Through Flac3 D three-dimensional finite difference software,the order of different steel pipe jacking and the cutting order of steel pipe are optimized.It is concluded that when the steel pipe is jacked at the same time at the same time,the structure of the steel pipe is smaller when cutting the steel tube in the longitudinal order of the tunnel,which is more in line with the actual engineering needs.Through the selection and comparison of pipe screen selection,the diameter of 2 m,wall thickness 20 mm,steel pipe with Q345 B,steel pipe spacing of 165~265 mm,and 20 steel pipes.(3)The influence of the jacking of the open type and the earth pressure balance type pipe jacking on the formation deformation is simulated.Under the same conditions,the surface subsidence caused by open type jacking is greater than the balance type of soil pressure.The disturbance degree of the jacking construction decreases with the distance from the distance to the top pipe,the closer to the pipe jacking,the greater the settlement.(4)Under the influence of static load,Based on the finite difference software,the stress and deformation of the steel tube and main structure and the settlement of the upper part of soil and building during the construction of Yingze Street large section tunnel in Taiyuan are analyzed by finite difference software,The order of the jacking of the left and right,the first and the next,the interval and the interval are put forward.Steel pipe cutting in sequence along the longitudinal direction of steel pipe,excavation of soil,steel plate and steel plate support are more appropriate. |
