Research On Structural Safety Assessment Of Highway Tunnel In Underlying Goaf Area And Construction Control Technology

With the development and improvement of road network in China,the construction of long highway tunnels will inevitably pass through the bad geological areas with the goaf area.Under the disturbance of tunnel construction,the geological defects caused by the second deformation of old goaf are the key problems that must be faced in the construction of new tunnels.Based on the South beam high-speed Huayingshan tunnel engineering,with the extensive investigation of the data of the goaf in Huayingshan mine goaf,the deformation law,mechanical behavior and construction control technology of the tunnel in the goaf areas are studied in depth by means of numerical simulation in this paper.The main research results are as follows:1?Based on the distribution and occurrence of the old goaf in the tunnel site,the basic concepts of the goaf are systematically expounded,the harm of different forms of goaf to the construction and operation of the tunnel is summarized,and the basic principle of the probability integral method and the shortcomings in the tunnel engineering are analyzed in this paper.2?The deformation control index and structural safety index of highway tunnel are put forward and its boundary value is determined.The distance,thickness and inclination of the goaf are selected as the main research factor,combining the geological data of the field goaf,the numerical model of 3 factors and 5 levels is set up,which lays the foundation for the safety and stability analysis of the road tunnel in the down goaf.3?The law of deformation of the tunnel structure and the changing rules of the indexes under the effect of 3 factors are studied systematically,the main and secondary and the significance of the influence degree of the 3 factors are analyzed by means of mathematical statistics,and the study shows that the influence of 3 factors on tunnel deformation and safety is as follows: distance>thickness>angle.4?3 factors are used as independent variables to fit the prediction expression of the tunnel safety and stability in the geological section of the goaf,which is used as the tunnel safety prediction model based on the project,and based on the safety boundary value of the two indexes,the influencing subzone of the goaf is carried out,and the safety of the tunnel construction in the goaf section is evaluated.5?In this paper,the construction control technology of the supporting tunnel under the inclined goaf section and the goaf section of the arch is studied,and the improvement effect of the grouting method and filling method on the tunnel is contrasted,and the study shows that the grouting method can guarantee the safety of the tunnel construction in the goaf section.In addition,the mechanical characteristics of the reinforcement process of the protective arch in the goaf section of the tunnel arch are studied,and the reliability and practicability of the reinforcement scheme are evaluated and verified.