Analysis On Mechanical And Seismic Behavior Subway Tunnel Constructed By Cover And Cut Reverse Method

In recent years, subway construction develops rapidly in china. There are 14 citieswhich have subways, and there are 20 cities where the subways areunder-construction. The study on new construction method and structural seismicresponse is very important to the subway development and structural safety. Subwaylines of city are usually under the main roads in consideration of the use of subwaylines, distribution of passengers, road network of urban and so on. The subway tunnelburied shallowly is usually constructed by cut-and-cover method which has greatinfluence on the traffic and surrounding buildings.In this paper, the cover and cut reverse method is adopted to construct the subwaytunnel buried shallowly. The roads can be quickly recovered and the influence to thetraffic is reduced. The little transformation of surrounding rock and surface settlementcaused by this method are beneficial to the safe of surrounding buildings. Meanwhilepart of underground structure can be used as a parking lot, and the situation of parkingdifficulty in the commercial center area can be improved. A detailed description onthe main technical problem of cover and cut reverse method is given in this paper, andthe important technology and item of construction is also pointed out. Using theelement birth and death module of ANSYS, construction of diaphragm wall, slab,pillar and the soil excavation are simulated. The results of internal force anddisplacement of structure, displacement field and stress field of surrounding rock areworked out, and they can provide reference for subway tunnel construction.A computation model of soil-structure dynamic interaction is established toachieve the seismic response time-history analysis of a cover and cut reversetwin-tunnel under the horizontal earthquake action in Tianjin. The results have beenanalyzed to obtain the tunnel structure's displacements, accelerations, internal forceresponse etc. The time-history analysis shows that tunnel structure vibrates in thehorizontal direction together with surrounding rock and there is no dislocationbetween them, but there is obvious dislocation between tunnel structure andsurrounding rock in the vertical direction. The maximum internal force of tunnelstructure is smaller, which is propitious to guarantee the structure safe under the earthquake action.