Study On Deformation Law And Construction Method Of Double-arched Tunnel In Complex Geological Conditions

With the development of expressway construction, a great number of highway tunnels have been constructed or under construction, and, it is difficult to avoid the bad environment, such as soft rock,joint,crack and soft interlayer; the new supporting theory is proposed along with"NATM"applied widely, so the old design theory can't meet present engineering; more double arch tunnels are constructed due to their particular advantages, however, the works are complex and disturbed each other. Especially, it is difficult to construct unsymmetrical double-arch tunnels, with their applied stress complex and variational.The thesis analyzes the different construction methods involving the three heading construction method, the central heading bench cut method and the central heading full cross method with 3-Dimention numerical simulation and data of the field ,concretely analyses the advantage and disadvantage of different construction projects in special surrounding rock condition and constructing process.The entrance section of FuXi Double-arched Tunnel is modeled in the fact of factual shallow buried and unsymmetrical pressure condition. Adopting the three heading construction method to simulate twelve kinds of construction projects, confirm reasonable construction orders and left and right tunnel face interval, systematically analyze and research the changing law of the tunnel deformation and surrounding rock stress in soft and cracked condition of surrounding rock,bring forward pertinent advices against construction disease; Build the deep buried tunnel model in middle section of tunnel , separately adopt the central heading bench cut benching method and the central heading full cross method to simulate ten kinds of construction projects, establish the reasonable construction orders, sidestep length and tunnel face interval, which are due to the deep buried tunnel, systematically analyze and research the change law of the tunnel deformation and surrounding rock stress in the section with good surrounding rock condition, bring forward the reasonable construction projects which can make sure of construction safety and save construction time; Because the central wall is disturbed many times during constructing process, its displacement and stress distribution is very complex. By comparing various kinds of construction projects, systematically research the changing and distribution law of the displacement and stress of the central wall in different constructing process, especially for the shallow buried and unsymmetrical...