Research On Construction Mechanical Behavior Of Laoanshan Large Span Tunnel Under Shallow And Weak Rock

In recent years, the rapid development of high-speed railway industry promote the rapid development of the economy and ease the traffic congestion, but a large number of large span tunnels also have sprung up, and many are in poor rock.Compared with the general tunnel, there are many difficulties and risks in the design and construction of large span tunnel, there is also no standard specification reference, with a certain blindness. Therefore, studying of such the excavation process and the mechanical properties of the support process and selecting the reasonable construction method are particularly important.Based on Xi(An) to Cheng(Du) high speed railway Laoanshan export large span tunnel project, through theory analysis and ANSYS numerical simulation combining method, this paper detailed analysis the tunnel in double sidewall drift method for excavation of vault settlement, bottom uplift, peripheral convergence, rock and supporting structure of the stress state of. It is a theoretical guidance for the construction of key parts, also proves that the Laoanshan export large span tunnel under mining supporting a scene of the supporting structure of the premise, using the design of excavation method, fully meet the safety requirements of tunnel structure.This paper also simulates and studies the four steps with double-side-drift method on site improvement. Compared with the double-side-drift excavation method, under the premise of ensuring the stability and safety of the tunnel, the four steps with double-side-drift method can speed up the construction progress and reduce the construction cost, is a feasible construction method. According to the field monitoring data showed that the overall trend of the simulation results and the monitoring data are basically the same, so this theory can provide a reference for engineering construction.