The Research On Design Of Ultra-deep Foundation Pit For Shield Tunnel

As the same as shield method, pit engineering is an ancient and contemporary engineering issue. When people comprise and select proposal to build highway crossing rivers, shield tunnel developed rapidly and applicants generally because of smaller area-occupy and less influence of the environment. The diameter of shield tunnel developed gradually large to three lanes. With the increase of the diameter of shield tunnel, the excavation engineering as supporting engineering of shield tunnel have large plane scale, depth diversification and bad geological conditions. So the risk of the excavation of ultra-deep foundation pit should be seriously.In the design of the ultra-deep foundation pit of the open excavation section in north band of Qiantang River shield tunnel excavation engineering, many kinds of pit structure type are applied in connection with varied continuous excavation,the engineering is economical and construciong convenient. The paper describes the experience of excavation safty level determine, retaining structure selection,design and calculate. At the same time this paper focused discusses the on the characters of the composite system of the main-body structure and underground continuous wall,the main points of structure calculate and analysis on economy. On the further, this paper put forward proposes for construction.The design of north bank of the Qiantang River tunnel open excavation section combines with ventilated vertical shaft of the tunnel, analyzed the3-dimensional and integrals. The research also includes the joint effect of the upper structure, pit and following pile basis, analysis on different sedimentation of adjacent sections. The research accumulates valuable experience on the design and construction of the same kinds of extra-deep tunnel on soft soil regions and stand-tall wind towers.