Study On Static And Dynamic Mechanical Behavior Of Large-span Column-free Subway Station Structure

Traditional subway station has a large number of structural columns in the public area,while structural columns can lead to the problems such as splitting the space,blocking the sight line and restricting the flow of people.In the peak period of passenger flow,the shortcomings brought by these disadvantages are more and more obvious.The large-span column-free subway station will be formed when the structural columns are cancelled.With the advantages of free-space,wide vision and higher efficiency of passenger flow,large-span column-free subway station are increasingly valued by people and applied continuously.The achievements of study on large-span column-free subway station are abundant.However,there are few researches on the comparison of the stress characteristics between different structural types of large-span column-free subway station,the change law of mechanical behavior when the influence factors such as span and depth of the subway station are changed,and the comparison of seismic performance differences.To solve these problems,this paper uses literature investigation,theoretical analysis and numerical simulation methods,making a comparative study on the mechanical behavior of two different structural types of large-span column-free subway station,variable section roof and arch roof,under the dynamic and static loads,in order to provide some reference for the design and selection of large-span column-free subway station in the future.The main research results are as follows:（1）This paper summarizes the structural characteristics of the four types of structures that can realize the large-span column-free subway station at present,compares them from the aspects of stress rationality and construction difficulty,and chooses the variable section roof which are most widely used with mature construction technology and the arch roof which have strong bearing capacity and large span capacity to be the vehicle of this study of the features in bear about large-span column-free subway station.（2）The stress characteristics of variable section roof and arch roof under different structural size parameters are analyzed,and the optimal structural size parameters of these two different structural types of roof are selected when they meet the actual requirements.For the variable section roof,the setting of the variable section size is the most reasonable when the section height ratio α=1.0 and the section length ratio β=0.5.For arch roof,it is considered that it is most appropriate to set the rise span ratio ω to 0.25.（3）In order to study the influence of span and depth on the stress characteristics of column-free subway station,five groups of calculation conditions of span and depth are set up.The mechanical behaviors of the column-free subway station with variable section roof and arch roof under the influence of span and depth are simulated and studied respectively,and the two kinds of mechanical behaviors are analyzed from two aspects of deformation resistance and stress characteristics.The results show that:the arch roof has more advantages compared with the traditional variable section roof when the span of subway station increasing,while the traditional variable section roof is more suitable for the larger station buried depth.（4）The EL-Centro wave is selected as the input wave,vertical and horizontal ground motions are applied at the same time,and the finite-difference software FLAC^3D is used to analyze the seismic response of the large-span column-free subway station with variable section roof and arch roof.The results show that the seismic weak position and failure form of this two types station are basically the same,and the shear failure is easy to occur at the connection part of the side wall and floors.However,in the seismic strength of the station,the large-span column-free subway station with arch roof has better seismic performance.