Dynamic Performance Study Of Subway With Steel Fiber Concrete Lining Based On SSI Theory

The destruction of subway lining segments started from the development and development of macroscopic cracks.At the current stage,the initial defects and material defects caused by engineering construction are the main reasons for inducing macroscopic cracks.The addition of steel fibers in concrete can effectively hinder the micro cracks in concrete.The expansion and the formation of macroscopic cracks can extend the life of subway tunnels and better meet the requirements for use.The lining segment mainly considers its shear resistance at the design stage,which often results in overstuffing of the stirrups,and the vibrating is not dense during the construction,leading to easy penetration of the segment at the use stage and affecting the durability and safety of the segment..Therefore,this article studies the steel fiber in the lining segment has a good crack resistance,cohesiveness and the role of replacing the stirrups,make up for the lack of the original concrete lining structure,improve the durability of the subway tunnel.In addition,the dynamic characteristics of steel fiber lining segments under soil-structure interaction are analyzed.The dynamic response rules of structures under seismic and train loads are studied separately,which provides a certain reference for the design and construction of subway tunnel linings,and has practical application value.The destruction signs of subway lining segments are the generation and development of macroscopic cracks.The defects of reinforced concrete lining materials and the defects of artificial cast-in-place construction technology are the main reasons for inducing macroscopic cracks.The incorporation of steel fibers in concrete can effectively hinder the micro-interior of concrete.The expansion of cracks and the formation of macroscopic cracks can extend the life of subway tunnels and better meet the requirements of use.The lining segment mainly considers its shear resistance at the design stage,which often results in overstuffing of the stirrups,and the vibrating is not dense during the construction,leading to easy penetration of the segment at the use stage and affecting the durability and safety of the segment.Therefore,this paper studies the role of steel fiber in the lining segment,the role of crack resistance and the role of replacing stirrups to make up for the lack of the original concrete lining structure and improve the durability of the subway tunnel.In addition,the dynamic characteristics of steel fiber lining segments under soil-structure interaction are analyzed.The dynamic response rules of structures under seismic and train loads are studied separately,which provides a certain reference for the design and construction of subway tunnel linings,and has practical application value.Through material substitution test and shaking table test,the rationality of application of steel fiber in lining segments was studied.Considering the shear state of the lining segments,the test components were reasonably simplified,and a simply-supported component that complied with the stress state of the arc arch lining was produced.The steel fiber substitution test was conducted on the bending and shear properties of the simply-supported component.It was found that the addition of steel fibers can not only improve the failure morphology of specimens and reduce the crack width,but also can significantly increase the residual bearing capacity and shear ductility of specimens after the ultimate load.Combining the cracking rules of simply supported members with different steel fiber content,the substitution effect of steel fibers on stirrups was pointed out.Using the steel fiber ratio of the steel fiber reinforced concrete lining obtained by experiment,the dynamic model of the shaking table was made,and the development trend and damage characteristics of the crack were analyzed.It was found that the cracks of the comparative model were concentrated on the bottom of the lining.And there are more cracks at the entrance of the tunnel,which means that the design of the junction between the tunnel and the station should be strengthened;in addition,the steel fiber has the role of sharing the shear force of the concrete,and can better limit the development of the penetration crack,which is conducive to improving the durability of the tunnel lining segment.At the same time,the discretization of steel fibers makes the distribution of cracks in the lining even more uniform,which is conducive to achieving the purpose of full deployment of lining segments.Combined with the background and settlement monitoring data of a subway tunnel in Shenyang,a finite element model of steel fiber reinforced concrete lining tunnel was established.The dynamic response law of steel fiber reinforced concrete lining under soil was analyzed by numerical simulation.On the one hand,under the action of the earthquake,it was found that the most unfavorable position of the lining is the right lower position,and the maximum stress occurs at the same time and the values are relatively close.Therefore,the full deployment of the lining segment should be paid attention to when designing;on the other hand,the train load should be used.Next,it was found that the displacement values of each node of the lining are relatively close,further illustrating the importance of full-scale defense during design.Comparing the two load models,the value of the vertical displacement of the joint calculated under the uniform load model is about 3.67 times that of the concentrated load model.Therefore,the uniform load model is chosen to make the design safer.The application of steel fiber reinforced concrete in lining segments can better restrict the development of cracks and improve the durability of the tunnel lining.In addition,the dynamic response rules of steel fiber reinforced concrete lining structure under the action of soil are studied,and it is found that steel fiber concrete has Good ductility and strong energy consumption are beneficial to the full deployment of subway tunnels.The paper has 100 figures,35 tables,and 159 references.