|
Abstract A new kind of construction method for metro station that a running tunnel with two tracks is constructed by large diameter shield machine and moreover the station is built by shallow mining method to enlarge large diameter shield tunnel has been applied to construct Jiangtai station of Beijing metro line 14. Taking Jiangtai station as the engineering background，In the process of enlarged excavation，The key construction stage is analyzed in detail according to the actual construction process，Three-dimensional finite element models are used to simulate the metro station construction on the basis of the ground-structure interaction. In the process of the pilot tunnels being asymmetric excavation and K shield segments being asymmetric dismantled，The mechanical performance variation law of the metro station structure is obtained. The numerical simulation results show that the structural stress state varies frequently in the process of enlarged excavation. Due to the pilot tunnels asymmetric excavated and the K segment asymmetric dismantled，The stress distribution of the primary lining structure，the segment and the middle partition wall will appears asymmetric state. The stress state of the segments shifts from the dominative compressive stress to the predominant tensile stress，The maximum main stress of the primary lining structure of the Pilot tunnel will appears after one side of the K segment dismantled. In the process of the pilot tunnel excavated，The maximum main stress of the middle partition wall structure will appears after one side of the pilot tunnel excavated， In the process of K segment dismantled，the middle partition wall structure will appears obvious asymmetric compression state，The asymmetric compression state will disappear and the maximum main stress will appears after both side of K segment dismantled. The numerical results show that the middle partition wall appears Obvious asymmetric compression state in the process of enlarged excavation and K segments dismantled. On the basis of the numerical simulation result and the middle partition wall strain monitoring result. The designing schemes such as the supporting parameters of the middle pilot tunnel and the excavation method of the middle pilot tunnel and the method of K segment dismantled etc are optimized to ensure the safety of enlarged excavation and the metro station structure.
|
|
|
|
|
|
2015, Vol. 34 
