Numerical Simulation Analysis And Stability Evaluation Of Tunnel Surrounding Rock Under Mined-Out Areas

South Lu Liangshan Tunnel is located in Linfen city in Shanxi province. It was designed to double hole single line tunnel. The maximum distance of two lines is 30m, as the buried depth is about 560m.The tunnel route runs between the east of south Lu Liangshan mountains chain and hilly area of Linfen basin margin. Tunnel pass through five coal mine and multiple mined-out areas. Mined-out area area surrounding rock is affected by mining activity, the prototype structure of surrounding rock is destroyed, rock mass is broken, developed greatly fissures and contained mined-out area dropsy. These adverse conditions will pose a serious threat to stability of south Lu Liangshan tunnel.Based on geological survey and tunnel goaf period, according to the preliminary design scheme elastic-plastic theory, waterproof safety coal-rock pillar theory and natural arch theory and theoretical calculated under goaf factors affecting the stability evaluation of tunnel construction tunnel condition, according to the method, we close to the stability of the influence tunnel design parameters. At the same time, this paper focuses on using FLAC3D numerical simulation software is analyzed in different goaf and tunnel mutual position, under the situation of coal seam before and after the excavation of the surrounding rock stress and displacement change, this paper systematically analyses the position of mined-out area and tunnel of relations and the effect on the stability of the tunnel safely. On this basis, but also put forward position relative to the tunnel of mined-out area concrete plan to prevent other schemes, possible disasters gives advice. Through the above research, this paper had analysed systematically not only the affecting factors of the surrounding rock stability in mined-out areas section of South Lu Liangshan tunnel, also numerical simulation according to actual condition, we had a quantitative research on the stress and displacement changes of surrounding rock, provided a theoretical basis in evaluating the preliminary design of South Lu Liangshan tunnel, provided security for future tunnel construction and safe operation. The conclusion is useful to similar project.