Study On The Excavation-deformation Behavior And Lining Stress Of Deep Buried Cross Tunnel

The excavation of the intersection tunnel between the separate and independent double tunnels makes the stress of the surrounding rock and the supporting structure of the chief tunnel release and redistribute of stress again, which gets the mechanics behavior of the rock mass and the supporting structure by the intersection complex change, and bring remarkable effect to mechanics and deformation behavior on surrounding rock of intersection part. Especially in the weak surrounding rock region, it always makes large deformation and plastic damage to surrounding rock that excavation of intersection tunnel. This paper depends on extra long deep-buried tunnel(Yangjiao Tunnel), through measured information at construction field, combined 3D elastic-plasticity finite element numerical simulation, study on the dynamic construction mechanics feature of intersection part of deep buried tunnel.â‘ Using the information of field monitoring measuring, make particularly comparison and analysis on displacement and stress feature of surrounding rock among weak surrounding rock intersection part, harder intersection part and normal part(non-intersection) before and after the excavation of intersection tunnel. The result of comparison and analysis indicates that the influence to weak surrounding rock intersection by the excavation of intersection tunnel is great and making large deformation. The excavation of intersection tunnel makes bias pressure to surrounding rock at intersection part, surrounding rock pressure at side intersection is obvious larger than that at opposite intersection.â‘¡Expound the basic theory of finite element simulation to underground engineering construction process. Using large scale finite element software ANSYS 9.0, makes 3D finite element numerical simulation to the construction process of the project. analyses the displacement and stress feature of chief tunnel surrounding rock far away from the intersection, intersection surrounding rock and initial support after the excavation.of intersection tunnel. Through analysis, it gets: the effected region of chief tunnel surrounding rock by the excavation of intersection tunnel is about 12 m around the intersection. The principal stress, shear stress and displacement at the surrounding rock of intersection side is most effected by the excavation. It appears many tension stress and compression stress concentration at the intersection after the excavation of the intersection tunnel, most of them is appears at abutment of intersection side and haunch of intersection sharp angle side.â‘¢Combined with the result of monitoring measuring and numerical simulation, make deep analysis to the feature of displacement of surrounding rock, the contact pressure between surrounding rock and initial support, the contact pressure between initial support and secondary lining, and gets the variation law with time and space of displacement, stress and contact pressure, bring forward the deformation and damage mechanism of surrounding rock in deep buried tunnel intersection part, provide engineering gist and practical experience to theoretical research and design construction optimization of deep buried tunnel.â‘£Under expounding the deformation mechanism of surrounding rock at intersection part, combined with the feature of stress vibration and plastic zone before and after the excavation of intersection tunnel of surrounding rock and support structure at intersection part by numerical simulation, deeply discuss the deformation and damage mechanism of surrounding rock at intersection part of deep buried tunnel.