Numerical Analysis On The Stability Of Surrounding Rock For The Shallow Buried Section Of Tunnel Through Fracture Zone With Saturated Water

The overlying strata of the entrance of the channel in mountain is thin in general, in most cases it belongs to strongly weathered zone, and the surrounding rock is commonly broken, so fracture zone of surrounding rock is frequently encountered in the shallow section in tunnels, which will bring about harm to projects. Especially in rainy season, because of the continuous rain, these rock fracture zones will store a lot of water, which sometimes can be viewed as full of water, and this will involve the problems of the fluid-solid coupling, making another difficult problem to the project. Based on Huiyaozi tunnel of Jianchang Liaoning engineering geology condition, in this paper a numerical analysis of the stability of surrounding rock research for shallow section of tunnel through saturated fracture zone is made with geotechnical engineering software FLAC3D.Based on Huiyaozi tunnel project construction and specific engineering geological conditions, applying three-dimensional models generated by FLAC3D to reductive tunnel construction process, using the three-dimensional tracking monitoring data methods, this paper analyzes the stability of surrounding rock of the tunnel in the excavation process by analyzing displacements of rock, stress of rock, plastic zone of rock and retaining structure. The main research contents:(1) Choose the method of numerical analysis to study the stability of surrounding rock in tunnel excavation process after summarizing the methods of the research of surrounding rock’s stability. Make and adjust the fluid-solid coupling numerical model procedures by FLAC3D and choose reasonable numerical analysis parameters in the process of debugging.(2) To simplify the practical engineering application, compare the different effects on the stability of surrounding rock of different excavation footage applying established the fluid-structure coupling numerical model and select a reasonable excavation footage according to the actual construction conditions; compare the full section of excavation and steps excavation method after a preliminary selection of excavations and select the reasonable numerical simulation construction plan.(3) According to the geological and constructional conditions of Huiyaozi tunnel, make the simulation excavation by FLAC3D for three-dimensional.In the process of numerical calculation, consider primary support (shotcrete and rock bolt support) and the second support (form built concrete) the influence of the stability of surrounding rock fully. Compare in different seepage conditions the stability of surrounding rock for shallow buried section of tunnel through fracture zone, and the results of the stability of surrounding rock are beneficial to practical engineering.