Control And Safety Analysis Of Tunnel Lining Structure Under Multi-source Loads

Railway tunnels as the important facilities on the railway line play an important part in improving line shape and shortening mileage. However, with the growth of the tunnel service time, Due to the designing, construction defects, as well as the external environment, Defects and diseases in various degrees occur on the tunnel structure, which will weaken the bearing capacity of the lining structure and will be a serious threat to the railway safety. Train dynamic load is one of most important factors that cause lining disease during railway operation. Based on a tunnel engineering, combined with site testing and numerical simulation method, the stability of tunnel lining structure under static and dynamic loads and tunnel disease prevention measures were researched, aiming to ensure traffic safety and extend the life of the tunnel. The main researching contents of this paper and results are as follows:(1) The common diseases occurring in the railway tunnel were summarized, and a comprehensive analysis of its formation mechanism and harm was conducted. Combined with a tunnel engineering, reading microscope, laser profiler, geological radar detection were used to inspect defects and diseases on the lining structure. Then, the security level of the lining structure was assessed at the same time according to the norms, and the results show the level was A1(serious). The tunnel structures needed to be reinforced. These original data would be used during the numerical simulation research.(2) Based on the tunnel structure theory, for the shortcomings of load-structure model, a typical cross-section of a tunnel of was selected to build plane finite element model by using strati graphic-structural modeling under the effect of static load. By calculating the bending moments and axial force of the lining structure, the plastic stage method was used to calculate the safety factor of the unit section to determine the security of the lining structure. Calculation results meet the specification requirements.(3) By using the dynamic finite element method, ANSYS software was used to build the dynamic finite element model of the typical cross-section of a tunnel under the action of multi-loads. Using artificial excitation function to simulate train load, lining structure under the effect of dynamic load of train and truck respectively were simulated. The results show that:the train vibration load has the greatest impact on invert arch and followed by side wall and vault. Truck load has the greatest impact on vault parts. Under the action of the train and vehicle load, there are greater tensile stress at the arch bottom and crown.(4) From vibration control and Lining structure disease treatment two aspects, based on a tunnel, lining safety control measures were proposed during its operation.