The Interaction Between Loess Ancient Soil Tunnel Surrounding Rock And Folding Steel Frame Support Lining Was Studied

The construction site of the tunnel is a process with high labor intensity and relatively low construction efficiency.In the past tunnel construction,due to the relatively short length of the tunnel,weak formations and poor geological conditions relatively good realization,the tunnel along the need for steel frame support is generally relatively short,therefore,the inexpension and high strength caused by the steel frame has not attracted relevant attention.In recent years,with the emergence of a large number of tunnels,tunnel length is increasing day by day,steel frame support artificial construction of this traditional construction problems are increasingly prominent,and gradually by most engineering technology and management personnel attention,how to achieve the tunnel steel frame support mechanization,high-quality and efficient implementation of tunnel support measures,has become one of the key issues to solve the rapid construction of the tunnel.The technical guide for railway tunnel engineering construction(TZ204-2008)and the technical guide for high-speed railway tunnel construction(iron construction No.241)provide for the construction process and processing requirements of the initial support steel frame,but lack the materials,forms,scope of application,processing process,transportation,installation and management process of the steel frame.According to the current steel frame design and construction mode,the site is difficult to follow the design to make the steel frame and different degrees of deformation of the surrounding rock close,construction quality is difficult to control.In this paper,a new type of folding steel arch proposed to solve these problems is studied,including the force characteristics and destruction forms of the new steel frame,construction organization problems and the law of support force change under different operating conditions,and the power response characteristics during the tunnel opening operation are studied,and the main results are as follows:(1)Based on indoor loading destruction test,numerical simulation calculation and analysis,the characteristics and influencing factors of the force damage of the new assembly folding steel arch are obtained,and the practicality and excellentness of the new folding steel arch are verified after comparison with the conventional steel arch installation method.(2)By adding lining springs between the beam units between the initial support and the two liners in the simulation,the construction process simulation under the structure-load calculation method is realized,and the internal force change law of the first branch and the second lining under the action of the ancient soil expansion load is analyzed,which provides suggestions for the practical use of folding steel arches.(3)Using the Modified Mohr-Coulomb model,which can better reflect the real situation of the soil,the influence of tunnel depth on tunnel lining and surrounding rock caused by mountain fluctuations is simulated,and the change of the internal force of the steel frame under the influence of different tunnel depth and the development and change law of formation perimeter stress are obtained.(4)Through the time-range analysis method,the lining response under the action of horizontal seismic load is simulated,the displacement response law,acceleration response law and stress response law of lining are analyzed,and the influence law of the relative position of ancient soil layer and tunnel on the dynamic response of tunnel lining is obtained.