Research And Optimal Design On U-type Trough Structure Of Underpasses Tunnel

Underpasses Tunnel are widely used in most city of our Country because they are not only more economical then any other bridges, but also as useful as other bridges. Generally, in order to ensure safety, the method of breaking traffic off is used. Therefore the traffic is become more and more crowding, and the problem is become more serious.In order to solve the problem, the paper propose a plan of temporary steel bridge design. According to peculiarity process of construction ,applying finite element software(Midas/Civil)to simulate process of temporary steel bridge working. According to the analysis of stress and strain, the plan is feasible. The plan can maintain normal traffic.According to the plan, the borehole cast-in-place pile is the basis of temporary steel bridge. The method has the excellence credible technology, agility economy and advantage construction, which is very suitable to the permanent foundation pit retaining in Bridge of Underpasses. The paper apply finite element software(FLAC3D)to simulate different length and diameter pile, then analyze discipline of stress and strain to find reasonable length and diameter pile. The method can as reference for design and construction.The excavation of the deformation characteristics are different from the general excavation deformation because of the force of temporary steel bridge. The paper apply finite element software(FLAC3D)to simulate the process of excavation. The paper analyses supporting structure stress manner and deformation characteristics in each process ,can master the security and stability of supporting structure at any moment, and provide effective and timely construction guidance.