Structure Stress Analysis Of Karst Tunnel Based On Long-term Structural Safety Monitoring

China is very mountainous and also has the largest and the most complex and fastest developing tunnel projects in the world. Tunnels take the advantages of the excellent linearity and can reduce journey time and distance effectively, so more and more tunnels are applied in traffic program. Due to the complex geological conditions of tunnels in karst area, a growing number of advanced technologies and new lining structures have been used in process of tunnel structure construction. Taking Qiyueshan tunnel for research background, amount of engineering geological data about its topography, lithology, structure and hydrological characteristics has been investigated and collected. The long-term structural safety monitoring system at the tunnel had been installed completely during the construction process. Meanwhile, the sensor system had also been arranged in the typical sections at the Qiyueshan tunnel. The long-term structural safety monitoring system was established in order to fully master the force condition of the tunnel structure during operation period and evaluate structural safety.By analyzing the real-time transmission data from the monitoring system, the stresstime curves of the forced lining structure and the section stress distribution map are plotted according to the analysis results. Then the change law of the curves and the distribution rule of the stress at each monitoring points in typical sections are studied to find out the point at peak stress. The change trend and rule of the peak point are analyzed emphatically, and the peak values are compared with the structural safety design values to evaluate the structural safety performance. In this thesis, numerical simulation model was established by ANSYS software for finite element analysis on tunnel lining structure. Then the simulation results was compared with the measured data analysis results to study the mechanical characteristic and change rules of karst tunnel lining structures to gain the most unfavorable force bearing point. Finally, those points were subjected to grey prediction. Grey prediction models on each points were established to study the mechanical trends and change law of the structure to verify the structural safety and tunnel stability in the long-term use of the tunnel.It can be concluded that the Qiyueshan tunnel structure possesses the long-term safety and stability. And the long-term structural safety monitoring system plays a significant role in providing safety basis and guarantee, which is of essential guiding significance in engineering practice and may provide a reference for building the karst tunnel safety monitoring system and the safety evaluation standard in the future.