| Tunnel boring machine（TBM）has the advantages of mechanization,environmental protection,high efficiency and light disturbance.It is one of the most important construction methods of tunnel engineering.The most important consumption of TBM construction is the disc cutter.How to quickly and easily judge the wear rate of disc cutter in the construction of a certain section of tunnel,and provide a theoretical basis for the development of cutter change plan and construction parameters,is an urgent problem to be solved to ensure the construction efficiency of TBM.In this paper,by means of theoretical analysis,field measurement,numerical calculation and laboratory test,and referring to the principles of tribology and material science,the abrasion of disc cutter in the process of TBM rock breaking is deeply studied.Based on the wear mechanism of disc cutter and the measured data of TBM section of the Winter Olympic tunnel project,this paper puts forward and verifies the cutter zonal wear theory;develops a set of numerical calculation method based on the rock breaking movement of disc cutter,and analyzes the stress law of disc cutter;designs and manufactures a set of indoor wear test equipment considering the rock breaking characteristics of disc cutter,and carries out relevant research on it,so as to improve the zonal wear theory.The main research results are as follows:（1）According to the principle of tribology,this paper analyzes the different wear types of different parts of disc cutter when breaking rock,and puts forward the zonal wear theory of disc cutter.It is considered that there are three main wear types.Through the deduction of the theory,the possible states of the wear amount when different zones play a leading role are obtained.According to the deduction results,the in-situ test is carried out,and the corresponding limit states are obtained The rock mineral composition analysis（Roqscan）and Cerchar abrasivity index（CAI）were carried out to verify the theoretical derivation and determine the rationality of the zonal wear theory.（2）Based on the discrete element particle flow software PFC3D,the numerical calculation method is studied.By comparing the compression and tension ratios of different numerical material models,the flat joint model is selected to model the rock mass material.The surrounding rock of TBM section of pipe gallery is sampled on site,and the uniaxial compressive strength and tensile strength of the rock sample are obtained through indoor test.The orthogonal test is designed to verify the model.The relationship between meso parameters and macro parameters is calibrated,and the back calculation formula is fitted;a set of numerical modeling method which can extract the force on one side of disc cutter independently is compiled by using fish language,and a real-time secondary decomposition method for rock breaking motion of disc cutter is developed in view of the situation that the numerical software can only output the XYZ direction,which can be decomposed into the lateral force of cutter according to the real-time position of cutter and rolling power.（3）The numerical simulation schemes of rock breaking by disc cutter under different surrounding rock conditions,different penetration conditions and different layout conditions are designed.The normal force,lateral force and rolling force of cutter under various working conditions are compared.The numerical calculation results show that the normal force,rolling force and lateral force of cutter will increase with the increase of disc cutter revolution speed;different installation radius The results show that the difference between the lateral force and rolling force under different installation radius is mainly caused by the different linear velocity of cutter,and the rolling force and the linear velocity of cutter have a linear positive correlation;the lateral unbalanced force of cutter under different radius is analyzed,and the results show that the difference between the lateral force and rolling force under different installation radius is mainly caused by the different linear velocity of cutter.The lateral force below 0.7m diameter has a linear negative correlation with the installation radius.With the increase of the radius,the unbalanced force will be infinitely close to 0.According to the results of numerical calculation and field construction parameters,the calculation method of single cutter force is modified,and the force of single cutter on the cutterhead can be calculated according to the construction parameters of TBM.（4）According to the motion characteristics of the hob in the process of rock breaking,a set of test equipment is developed to distinguish the front fracturing wear and sliding wear of the hob.Based on the electromagnetic sensing equipment,the number of revolution and rotation of the hob is accurately recorded.The test results show that:the proportion of the front sliding distance of hob is mainly affected by the contact pressure,and the overall linear negative correlation;through the wear test of the steel ring specimen,the fracturing wear and sliding wear in the front wear are distinguished,and the test results show that the fracturing wear is only related to the contact pressure and the properties of the steel ring material,and has nothing to do with the properties of the surrounding rock,the fracture radius is 2.4×10-6 mm/Mpa·r;（5）According to the results of numerical calculation and laboratory test,a set of iterative calculation algorithm of hob wear based on construction parameters and surrounding rock properties is compiled by using MATLAB.After substituting the wear coefficient obtained from laboratory test into calculation and calibration,the fracturing wear coefficient of field hob material is 0.3165×10-6 mm/Mpa·r,the difference between the calculated results and the measured data is less than 5%,which verifies the accuracy of the zonal wear model algorithm. |
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