Study On The Overall Properties Of The Shield Tunnel Based On Shell-spring Model

As the development of economics and the improvement of Comprehensive national strength in our country,speeded-up of the urbanization process,It is inevitable to Carry out urban construction in large scale,In these underground projects,the shield method which makes little impact on the cities' normal function is paid more attention and widely used in some areas because of the constraints of traffic and construction site or the other urban environmental factors.However,the blindness of the shield tunnel design because of no specialized design code makes it is necessary to strength theory guidance.The key of the shield tunnel lining design depends on whether the structural model can reflect the actual stress.Currently,there are four main numerical analysis methods of tunnel lining horizontal theories.They are:wont method,revised wont method,multi-hinge loop method and beam-spring model.The vertical theoretical analysis methods are:the vertical beam-spring model and the vertical equivalent continuous model.The Several models mentioned above all simplify the segment to beam along the horizontal or vertical,and consider the properties of horizontal and vertical structure respectively,without exception.However,the structure is complex because the shield tunnel is a kind of circle structure which is assembled by several segments and connected with bolts,so the properties of horizontal and vertical structure are inextricably linked.The properties change of the vertical structure will cause the properties change of the horizontal structure inevitably,it is the same in contrast.In many cases it is difficult to accurately reflect the structural properties between the segments by simplify the segment to beam along the horizontal or vertical.So there are some actual performances of mechanical characteristics and structure differences exist.In this paper,the research work is carried out based on this.The main research contents are below:1.Based on the analysis of the existing shield tunnel lining segment,three-dimensional equivalent continuous shell-spring model which could reflect the mechanical characteristics of the shield tunnel lining segment more comprehensively is put forward.The rectangular flat shell element is used to simulate the lining segment,and spring element with soil to simulate the formation and the interaction between the tunnel structure and the layer.2.The shell-spring model is used to analyze the overall mechanical properties of seam pass lining segment.The mutual influence of the vertical and horizontal structure is studied in light of the mechanical mechanism.And the influence which the foundation stiffness change has impact on the tunnel structure is not particularly evident.The results show that:the influence the loop stiffness change which has impact on the longitudinal is more than the longitudinal stiffness change which has impact on the loop when seam pass segments are assembled;The properties of the tunnel structure is not very sensitive to the change of foundation stiff;According to the analysis of the calculation results,the concepts of"the vertical strengthen effect by seam assemble"and"the horizontal strengthen effect by assembled Lining"are put forward.3.The shell-spring model is used to analyze the overall mechanical properties of seam pass lining segment,and the mutual influence of the vertical and horizontal structure is studied in light of the mechanical mechanism.The results show that:the influence the loop stiffness change which has impact on the longitudinal is more than the longitudinal stiffness change which has impact on the loop when the load center is near;when the load center is far,the result is on the contrary.According to the analysis of the calculation results,the calculation results verify the vertical strengthen effect by interlaced assemble again which the predecessors put forward, and the existence of the horizontal strengthen effect by assembled Lining which this paper put forward.