Three-dimensional Force Analysis And Improved Design Of Urban Utility Tunnel Intersection

There is a growing number of the urban utility tunnel with more attention paid on the underground space in recent years.In the utility tunnel design,the utility tunnel intersection is often different from other utility tunnel nodes.Due to technological layout requirements,the intersection not only needs to ensure the pipeline connection,but also to provide the convenient contact for people.Besides,it can't be calculated as plane force model simply.So in this paper,the three-dimensional finite element analysis of an actual intersection project is carried out according to the characteristics of the intersections' technological layout.The improvements and the detailed design are provided based on the unstable position.The final conclusions are as follows:1.The design key points of utility tunnel intersection should be found according to the technological layout.In terms of force,the utility tunnel intersection roof is weak in force and deformation.Utility tunnel intersection roof.middle plate and floor are under bidirectional loads,and upper sidewall and lower sidewall are under approximate unidirectional load.The vertical displacement of the whole intersection is larger than the horizontal displacement.2.In the improved design,the stiffness of roof should not be neglected due to the thickness,beams and plates deform together.The bending moment and shear force of the girderless floor model at the end of the column are large leading to the failure of punch shear.3.The increasing the vertical foundation stiffness can improve the uneven settlement of foundation making the foundation local reaction going up badly.The increasing the horizontal foundation stiffness can preferably limit the intersection lateral deformation.If the constraint of lateral stiffness is neglected,it will result in inaccurate calculation of the model.4.In finite element analysis,smaller haunch can not significantly improve the internal force value.Changing the type of concrete has little effect on the internal force of the structure.Structural design of expansion joint should be strengthened5.In engineering design,structural and durability design should be strengthened.Reinforcement can be obtained by internal force calculation.