Rostami Alireza, Hosseini Navid, Adib Ahmad, Roozbahani Hesamedin
Symposium and workshop of sustainable development and urban management, Tehran, Iran
Publication year: 2013

One of the factors affecting the stability of tunnels and the amount of stress is the geometry of the tunnel section. Section geometry is selected according to the method of execution, type of use, technical constraints, etc. This article evaluates the cross section of the Karaj two metro line tunnel and its effect on the level of stability. The cross section is considered in two oval and circular modes and then according to the geomechanical parameters, the route of the Karaj two metro line is modeled in plaxis 7.2 2D software. Each model is analyzed by two-dimensional finite element method, before and after the application of concrete coating. The results of this study indicate that increasing the drilling space in the circular section compared to reducing the drilling space due to reducing the distance from the crown to the tunnel floor in the oval section, will cause more stress concentration. Therefore, the stability of the egg cross section is higher in these conditions. Also, the distance between stress changes and displacement in the crown and wall of the tunnel with the oval cross section is shorter than the circular cross section.