Finite-element Analysis And Testing Of Seepage For Rebuilding Tunnel

With the rapid development of traffic, higher standards of constructing tunnels are required for railway operation. In order to reduce the waste of resources and labor forces, more and more tunnels, which can not satisfy the technical standards, are rebuilt to meet the new transportation demands. Therefore, the research of stress distribution and seepage testing of rebuilt tunnel becomes much more important.The mathematical and numerical methods are combined to study the stress and deformation of rebuilt Chenjiachong tunnel. The distribution of stress is achieved, which can be a valuable reference for rebuilding tunnels.Firstly, the stress of the circular tunnel which is in the initial geostatic stress field is analyzed. Based on some assumptions of the surrounding rock, the analytic formulae of the area of plastic zone and displacement are presented by using yielding rule (Drucker-Prager).Secondly, the quadratic formula for stress of circular tunnel is deduced. When rebuilding the existing Chenjiachong tunnel, the numerical analysis using ANSYS program is performed in two working conditions that the seepage is considered or not. Meanwhile the worst factor that crack is existed in the structure is also considered. After comparison, several significant conclusions are drawn.Finally,the seepage of junction between fresh and old concrete is tested by using the ground penetrating radar and microwave humidity equipment. Through comparing with the results monitored by the ground penetrating radar and those tested by microwave humidity equipment, the results are coincided with each other. And the results tested by microwave humidity equipment can reflect the seepage situation of the tunnel and the depth of the seepage more accurately. Moreover, the corresponding measures were adopted for the area of seepage in order to satisfy the operation demands of the tunnel, the tunnel is successfully rebuilt.