Abstract
Fatigue damage is one of the most common failure modes of large-scale engineering equipment, especially the full-face tunnel boring machine with characteristics of a thick plate structure bearing strong impact load. It is difficult to predict the location and propagation life of crack of cutterhead under strong impact load. Unseasonal maintenance of equipment caused by inaccurate prediction of life cycle of cutterhead seriously affects the construction efficiency of the equipment and the life safety of the operators. Determining the crack location of tunnel boring machine cutterhead structure under strong impact load and predicting the crack propagation life are difficult scientific problems. To solve them, first, the location of the stress concentration of the cutterhead is determined by using finite element analysis method of statics. Second, prediction model for crack propagation life of tunnel boring machine cutterhead characteristic substructure based on time integration is built. And the test of crack growth of cutterhead characteristic substructure is performed. The feasibility and accuracy of the prediction model are verified by contrasting crack prediction models and the results of the test. Finally, the life prediction of tunnel boring machine cutterhead of water diversion project in Northwest Liaoning Province is carried out by using crack propagation model based on time integration. Results show that the maximum error of theoretical prediction and experimental results of crack propagation is 16%. So the feasibility of crack propagation model based on time integration in predicting the crack growth of cutterhead is verified. It is predicted that the tunnel boring machine cutterhead panel can work normally for 5.9 km under the condition of ultimate load. Building the crack propagation model considering the influence of plate thickness and strong impact load has important research value for improving the working efficiency of engineering equipment, prolonging service time, and improving the working safety.
Highlights
Cutterhead located at the front of tunnel boring machine (TBM) is the core component of TBM, and has the function of breaking the rock and stabilizing tunnel face
Through the crack life expansion curve, it is not difficult to find that the prediction results of the crack extension prediction model based on time integral are more accurate than the traditional fracture mechanics model for fatigue life prediction
A crack growth model for the characteristic substructure of TBM cutterhead panel is established based on the time integration method, aiming at the TBM cutterhead panel in engineering
Summary
Cutterhead located at the front of tunnel boring machine (TBM) is the core component of TBM, and has the function of breaking the rock and stabilizing tunnel face. Crack propagation reduces the strength of the whole cutterhead greatly; leads to the vibration intensification and the failure of the whole equipment, which seriously reduces the construction efficiency; and even threatens the life safety of the front-line constructors.[1] TBM cutterhead welded by several hundred thick plates inevitably has initial defects. This leads to the short crack initiation time, which indicates that the crack propagation life accounts for more than 90% of the whole cutterhead life. How to quickly and accurately predict the crack location and crack propagation life of TBM cutterhead has important research value for improving TBM work efficiency, prolonging TBM service time, and improving TBM work safety
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