Construction Mechanical Behavior And Key Technology Of Spacial Intersecting Section In Subway Station

With the development of domestic economy, urban population increases sharplyand the problems of urban land and traffic congestion have became prominent problemin many big cities of our country. Unban rail transit is an important means to solve therestriction. The study on mechanical behavior, structure stability analysis and the effectson surrounding environment and buildings becomes quite important.This paper briefly reviews the current research status on tunnel intersection andadjacent section domestically and abroad. On the basis of the theory, taking Chongqingrail transit line six as the project example, firstly, the types of station intersections areclarified; then the ANSYS finite element analysis model are created based on theclassification; thirdly, the displacement and construction mechanics of intersections inevery type are studied and strength reduction method are used to analyze the stability ofstructure in intersections,at the same time determine the safety coefficient; finally, thepractical engineering is combined to research on construction and design. The researchdraws the following main conclusions:①The maximum tensile stress appeared at the plug wall of connection section,vault of intersecting section and corner of inverted arch in the intersection. These partsare the key areas for reinforcement. The maximum of vault settlement and groundsettlement appeared in the vault and surface of tunnel intersection or connected section.②The preliminary support and secondary lining in the intersecting section arecommonly in pressure stress state and the tensile stress appeared in the bottom ofinverted arch and vaults, as well as connection part and the place around the intersectingsection. The effect of branch tunnel to the main tunnel in the station is distributed in therange of3-4spans along the main tunnel axis and the displacement in the intersectingpart increased obviously.③The rock of plug wall is in tensile state owing to unloading effect. Excessivedeformation and block dropping easily appeared. These parts were the weak links indesign and construction and the partial place should be strengthened.④Structure in each intersecting section was in stable state and the safetycoefficient always in the scope of3-4. The minimum safety coefficient of2.8appearedin the intersection of station, ventilating duct and turning-back tunnel.⑤Combining with the engineering example to do research on design andconstruction, we obtained two excavating method and strengthened measures inconstruction of the intersecting swap area. The key points and quality controlling pointswhich need special attention in construction are summarized.