Characteristics Of In-situ Stress And Analysis Of Excavation Stability On The Surrounding Rock In Long And Large Tunnel

In-situ stress is one of the basic geological conditions in the construction of civil engineering and hydrautic engineering and is also a necessary condition for the design and construction of geotechnical engineering, such as tunnel and slope. Based on the previous research results and practical measurements of the in-situ stress, this paper made a systematic and comprehensive analysis on the theory of in-situ stress testing and analysis in the He Jialiang tunnel project by using the knowledge of rock mechanics, mathematical statistics, the finite element theory numerical analysis method and so forth. The effect of in-situ stress on the stability of surrounding rock was also considered at the same time. The research was expanded to achieve the purpose of combining theoretical analysis and practical engineering together from tunnel excavation footage, countermeasures of excavation method and deformation support.The main research achievements were as follows:1. The methods and the present situation of in-situ stress measurement, simulation, analysis and the stability of surrounding rock were introduced by studying the literatures and reports at home and abroad.2 The in-situ stress measurement theories of traditional hydraulic fracturing method and 3D hydro-fracturing in 3 crossed boreholes were used to analyze the results of in-situ stress test in different positions and depths of the He Jialiang tunnel project.3. Based on the data of the in-situ stress test and engineering geology, the in-situ stress field was analyzed by using the random weight particle swarm optimization algorithm for inverse finite element calculation. According to the result, the change law of initial stress field of rock was gotten and the in-situ stress state was classified and determined.4. Using the result of the initial stress field as the boundary conditions, the mechanic mode of the He Jialiang tunnel project was built by ABAQUS to simulate and analyze the construction process. The laws of the stress, displacement of surrounding rock and the distribution of the plastic zone were analyzed during different excavate footage and excavate methods. Influence of anchor length on stability of the surrounding rock in deformation control technology was optimised during tunnel construction project.