NUMERICAL SIMULATION OF ULTRA-HIGH PERFORMANCE CONCRETE REINFORCED SHIELD TUNNEL UNDER UNLOADING CONDITIONS
In order to investigate the force and deformation characteristics of ultra-high performance concrete(UH-PC)reinforced shield tunnels under the unloading disturbance of side pit excavation,MIDAS GTS NX software is used to construct a three-dimensional refined finite element model of the shield tubular sheet,and the convergence deformation of the tubular sheet before and after reinforcing the tubular sheet,the bolt stress,and the plastic defor-mation of the tubular sheet are used to evaluate the reinforcing effect of UHPC on the tubular sheet.The study shows that UHPC reinforcement effectively restricts the convergence deformation of the top and bottom of the tube sheet.UHPC reinforcement improves the overall structural stress performance,and the maximum reinforcement efficiency reaches 50%.After UHPC reinforcement of the tube sheet,the impact of shear action between the adjacent blocks in-side the single-ring pipe section has been effectively reduced,and the deformation at the joints of the tube sheet is restricted.Before and after UHPC reinforcement,the sensitive area of the tube sheet's plastic development is mainly located in the left and right waists,and local reinforcement measures can be taken in these locations.Local strength-ening measures can be taken for these positions.