The Study Of Surrounding Rock Stability In Construction Method Of Reservation Rock Beam And Pillars In Model T Of Super-large Cross-section And Shallowly-buried Subway Station

The construction of urban underground engineering has entered a period of rapid development due to the fact that urban traffic congestion becomes more and more serious with the increase of urban population and the expansion of city scale.Many subway stations,lines under the ancient buildings,highways,railways,rivers,residential areas,oil and gas pipelines,resulting in particularly complex construction environment.Therefore,it is of great significance to study the subway safety construction under complex environment.Toutang station in line 4 of Chongqing rail transit belongs to super large section shallow buried subway station,and the excavation length of the subway station is 26.4 m,the height is 28.2 m,the sectional area is 667 m2,and the depth of the top surface is about 20.0-32.4 m.The station is located in the intersection overpass of inner high-speed and Haier Road,which is the transfer station of metro line four and line nine.The station is arranged paralleling to the Haier road roadside underground layout in east-west direction and in the Xiazibian overpass just below.Xiazibian overpass and inner high-speed in Chongqing city belongs to the main road with heavy traffic.Underground pipelines on both sides of the roads are dense,so the environment of the station is very complex and the construction is difficult.In this paper,the surrounding rock stability in construction method of reservation rock beam and pillar in model T is studied by theoretical analysis,field test,laboratory test and numerical analysis.The main conclusions are as follows:(1)The classic rock pressure theory of soil column theory,Protodyakonov's theory,Terzaghi theory,Bill Bauman theory are used to calculated the vertical surrounding rock stress and horizontal stress during tunnel construction.The results show that the Terzaghi theory is suitable for the station.(2)The surrounding rock deformation,vault settlement,surface subsidence,the anchoring force are monitored in construction method of reservation rock beam and pillars in model T.The Peck formula is used to analyze the vault settlement,ground settlement,and forecast.(3)The construction of the subway station surrounding rock micro rupture signal is monitored by microseismic technology.It is indicates that the construction method of reservation rock beam and pillars in model T is suitable for the construction of large section shallow buried subway station.(4)The finite element software 3D-? is used to analyze the stress and deformation characteristics of surrounding rock during the excavation process of the station.It is indicates that the oretical calculation,field monitoring and numerical analysis are basically consistent.