Single Arch Four-lane Highway Tunnel Construction Method Of Numerical Simulation And Seismic Response

With the rapid development of the large-span tunnels' construction, more and more problems have come up. The present tunnel design and construction code can only be used to guide the design and construction of two-lane or three-lane tunnels, but can't meet the design and construction demand of the four-lane tunnels. Besides, there are not many relevant research achievements at both home and abroad, so the design and construction experience we can draw upon is very limited. Thus, our design and construction is of certain aimlessness. Meanwhile, because the rise-span ratio of the large-span tunnel is comparatively small, the properties of the surrounding rock and support lining are completely different in the process of the tunnel construction. Therefore, this paper makes a thorough and analytical study of the different construction conditions and the earthquake dynamic response of the four-lane road tunnel. The main research of this paper is as follows:Firstly, this paper compares the theory solution with the FE solution of the cross-section shape optimization of the tunnel, then analyses and derives that the rise-span ratio is the control index of the tunnel cross-section' shape optimization, and the maximum principle stress increases with the rise-span ratio's decrease, and the redistribution stress of the surrounding rock is much more complex. Besides, the rise-span ratio of the four-lane road tunnel is more or less 0.55. Secondly, based on the large-span tunnel's construction methods and excavation principle, the author makes a detailed analysis of the four-lane tunnel's different excavation method, such as benching method, CRD method and sidewall drift heading, which thus solves the problems concerning the large-span tunnel's excavation methods' choice and the stability of surrounding rock and lining.At last, according to dynamic principle, the author analyses the tunnel's displacement, velocity, acceleration and stress dynamic response analysis in the seismic force by different kinds and directions of earthquake, different surrounding rock's grades and depths of tunnel, then makes a comparative study of them. So the fierce earthquake, the slant forty-five degree seismic inspirit direction, the high grade surrounding rock and the more depth tunnel is much more fierce response, and must be strength the lining to anti-earthquake.From the above conclusions, the paper can provide the reference to the revision work of the anti-earthquake code in terms of construction finite element mechanics and technique analysis.