Analysis On The Fatigue Life Of TBM Cutter Seats

With the rapid development of tunnel construction in today’s society,Full face rock tunnel boring machine(TBM)tunnel construction has become one of the most important construction methods in underground construction.During TBM construction,the cutting body works directly on rock plate and are prone to fatigue damage due to strong vibration generated from the way it breaks rocks.The cutter head system is the most critical component of TBM rock breaking.The repair and replacement of the cutter head system is not only expensive but also time costly.Therefore,the effective analysis of the fatigue life has a positive effect on project cost reduction and construction efficiency improvement.Engineering studies have shown that,cracks occurred in a cutter seat-the typical structure of TBM is the most common cause of failure for TBM cutter head structure.In order to study and analyze the fatigue life of the TBM cutter head structure,the main research contents of this paper are as follows:(1)Finite element analysis of TBM cutter seat: first analyzes the mechanism to cause fatigue damage and the mainstream fatigue life analysis method of welding structure,then builds a model of the typical structure of the TBM cutter seat with weld.The corresponding finite element analysis is carried out on the TBM cutter seat.(2)Fatigue life analysis of TBM cutter seat based on equivalent structural stress:combined with finite element analysis and experimental load history,the dynamic stress loading time history can be obtained.Next,the Verity method and the traditional nominal stress method are used to calculate the fatigue life of the model.The influence of loads on TBM cutter seat’s fatigue life in different positions and the the influence of three-directional loads on the fatigue results are analyzed.(3)Research on nonlinear fatigue damage model: Considering the fact that the current mainstream fatigue life analysis is based on linear damage accumulation criterion,this paper delves into the study on a special non-linear fatigue cumulative damage model and get the uniaxial nonlinear damage cumulative model,multi-axis proportional non-linear cumulative damage model and multi-axis arbitrary load nonlinear cumulative damage model.The fatigue life analysis of the TBM cutter seat was carried out by using the uniaxial nonlinear model.The results show that the fatigue life of the cutter seat part calculated by the load of the center knives of the TBM cutter head is higher,and the overall fatigue life of the cutter seat part calculated by the load of the other positions is lower,and as the radial distance of the load position decreases,the corresponding obtained The fatigue life of the cutter seat part is also decreasing.The fatigue damage caused by the lateral force in the three-directional load is much greater than the positive thrust and rolling force.Non-linear fatigue damage takes into account the damage caused by the interaction between loads,and the calculated fatigue life is more conservative.It can provide an effective reference for the design of the TBM cutter head.