| Karst stratum are widely distributed in China, the filling karst geology with unique physical and mechanical properties was formed by the special occurrence environment and geological forces. Due to a series of problems existing in the research of the filling karst geology and the particularty of engineering geological disasters, now the related research on surrounding rock collapse mechanism of filling karst are rarely. Along with a large number of tunnel enfineering had been built in filling karst, the collapse disaster of surrounding rock and collapse disaster prevention and control problems in karst had become increasingly prominent, so need to carry out the research on collapse mechanism of surrounding rock and collapse prevention and control technologies in filling karst, to provide theoretical basis and technical support for tunnel construction and operation in filling karst. This paper takes Yangling tunnel filling karst geology as the research object, using numerical simulation, theoretical analysis, field test technology, study on surrrounding rock plastic zone development and distribution characteristics in filling karst body under the condition of different scale, spatial position state, different mechanical parameters, revealing catastrophe and progressive collapse mechanism of surrounding rock in filling karst, And put forward surrounding rock collapse prevention and control technology through the two kinds of catastrophe model. The thesis got main conclusions as follows :(1) According to Yangling tunnel regional engineering geology and hydrogeology, analysis of the development conditions of Karst, study on the karst occurrence characteristics of Yangling tunnel on the basis of the geological theory; Combined with the geological mechanics and the tunnel construction mechanics, analysis of the influencing factors of filling karst surrounding rock collapses, Using analytic hierarchy process to determine the main factors that influence the filling karst surrounding rock collapses, on this basis, using the orthogonal experiment method to get the main factors that influence the filling karst surrounding rock collapses of significance.(2) Based on the filling karst occurrence characteristics and its influencing factors on the stability of tunnel surrounding rock significant analysis, study on the filling karst surrounding rock displacement, stress and distribution regularity of plastic zone development by FLAC3 D numerical model, reveal filling karst area surrounding rock failure and instability mechanism under catastrophe and progressive collapse.(3) Based on catastrophe theory to study the mechanism of catastrophe collapse, build the cusp catastrophic model of key strata, export mechanical critetion of key strata failure and instability, reveal surrounding rock displacement, plastic zone volume jumping, lag and multi modal characteristics of catastrophe collapse, combined with the thin plate theory and the classical strength theory, export the minimum thickness empirical formula of key strata.(4) Study on the progressive collapse mechanism by using control variable method, analysis of surrounding rock displacement, stress and distribution regularity of plastic zone development, reveal the progressive damage and hysteresis characteristics; summarizes three control state of progressive collapse scale under the two factors of filling karst body and fault.(5) Based on the filling karst occurrence characteristics and collapse mechanism, study on the filling karst area surrounding rock collapse prevention and control technologies, in view of catastrophe collapse, put forward bad geological location, rock reinforcement and advance support technology; in view of progressive collapse, put forward bad geological location and the informationization construction technologies; in view collapse control problem of the filling karst surrounding rock, put forward collapse emergency measures and collapse management technologies. Based on this research results of filling karst area surrounding rock collapse control technologies, put forward the filling karst area surrounding rock collapse prevention and control technologies solutions of Yangling tunnel, and successfully applied in engineering practice. |
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