Research On Calculation Of Main Bearing Life Based On Shield Tunneling Parameters

In today's tunnel construction,the use of shield machines is more and more common.In order to ensure the reliability and safety of tunnel construction,shield machines must be made to work stably and normally.As the most critical part of the shield machine,the reliability of the main bearing operation is very important.The main bearings of shield machines are mostly three-row cylindrical roller slewing bearings.Their structures and loads are complex,the overall size is large,and there are many rollers.Under the action of bearing axial force,radial force and overturning moment,pleasing contact with the roller raceway easily produces large contact stress and deformation,which seriously affects the normal operation of the main bearing.Therefore,it is very valuable to study the bearing capacity and service life of the main bearing.Using a large amount of dynamic data collected during the tunneling process of the shield tunneling machine,the life of the main bearing of the shield tunneling machine is analyzed and researched,so as to maximize the economic benefits of the shield tunneling machine and improve the level of tunnel construction.Taking Fuzhou Rail Transit Line 1 tunnel construction shield machine as the research object,under the geological conditions such as silt,silty clay,medium sand,fine sand,etc.,the in-depth analysis of the shield machine load and the main bearing load distribution were calculated.The load size of each roller of three rows of rollers and the distribution law of the load of each row of rollers were obtained.The rolling bearing contact theory was used to calculate the contact stress and deformation of the three rows of rollers,and then the ANSYS finite element analysis software was used to simulate the roller raceway contact model.The results were basically consistent with the theory,and the feasibility of the finite element method was verified.In view of the particularity of the structure and load of the main bearing of the shield machine,based on the rolling bearing life theory and Palmgren-Miner's rule,a set of calculation methods for the fatigue life of the main bearing of the shield machine under composite working conditions was proposed.The fatigue life of the main bearing under the composite working conditions was obtained by the tunneling machine's driving parameters,geological parameters and the shield machine's structural parameters.In order to further study the influencing factors of the life of the main bearing,the change law of the life of the main bearing was calculated from the four situations of the number of rollers,the diameter of the roller,the diameter of the track pitch circle and the contact length of the roller raceway.According to the minimum life of the main bearing 10000 h,combined with the life calculation method of the thrust roller bearing,the maximum thrust of the shield machine was deduced,and compared with the rated thrust of the shield machine,it was basically satisfied.Based on the tunneling parameters of the shield machine,the bearing capacity and fatigue life of the main bearing of the shield machine are analyzed,which provides a certain reference for the design optimization and working reliability research of the shield machine.