Study On The Stability Of Surrounding Rock In Xinjiang Guozigou 1~# Tunnel Of The West-East Gas Pipeline

The Second West-East Gas Pipeline project is the first large pipeline project that introduce natural gas from outside of the China. the project from Xinjiang Huoerguosi ports in the west to Guangzhou in the south and Shanghai in the east, cover over 14 provinces and municipalities. It has strategic importance in the distribution of the national natural gas pipeline network. As a result of the complicated geological conditions of the engineering region, the project has to pass through the tunnels during the construction. As the first tunnel in China, it has great importance to study the stability of surrounding rock in Xinjiang Guozigou 1^# tunnel.The research is depending on the project of the Geological Safety Assessment of Xinjiang Guozigou 1^# tunnel in The Second West-East Gas Pipeline project. Based on Summing up the results of previous studies, the thesis analyzed the topography, hydro-meteorological, layer, geological structure and other conditions of the engineering field; discussed the factors that influenced stability of surrounding rock; In the basis of gathering on-site investigation information and in-outdoor test results, classified the surrounding rock of tunnel; On this basis, chose the typical profile, carried out numerical simulation of stability of surrounding rock in natural conditions and seismic conditions with the use of FLAC^2D software. The main research results are as following:1. The thesis has analyzed the layer, geological structure, degree of weathering, water and weather conditions and earthquakes and other factors of the engineering field that influenced stability of surrounding rock. Various factors that influenced stability of surrounding rock were consider In the use of numerical simulation, such as fissures, faults, groundwater and earthquake.2. Based on collecting of the on-site investigation information and in-outdoor test results, classified the surrounding rock of Xinjiang Guozigou 1^# tunnel with the use of national standard " standard classification of engineering rock " (GB50218-94). The results show that low-quality rock of gradeâ…£is mainly distributed in the depth of 100m from the hole,â…¢type of rock mainly concentrated in the range of 150m hole, the better quality rock of Classâ…¡is distributed in depth from 150m to 460m hole.3. In the basis of rock classification, selected four typical profiles, calculated the stability factor of the tunnel in the natural condition and seismic conditions the use of numerical simulation software FLAC^2D, and analyzed the plastic sub-area, stress and displacement in the different conditions. From the calculation results, the stability factor of the tunnel had reduced in the earthquake conditions. Lots of surrounding rock had good stability with the exception of the impact of rock near the fault zone. Finally, a reasonable treatment and recommendations were given to ensure the stability of the tunnel.