| The disc cutter is an important part installed on the cutter head of a rock Tunnel boring machine(TBM)for breaking the rock.However,due to the inclined installation angele of the gauge cutter,the force is more complicated,the linear velocity is large,the rolling path of the hob is long,and the wear is more serious.At the same time,due to the complexity of the geological conditions,the conditions of the underground rock mass also have an important influence on the rock breaking by the cutter.Therefore,exploring the rock breaking mechanism of TBM gauge cutter has an important theoretical guiding role in optimizing the layout of gauge cutter and reducing cutter wear.Relying on the National Natural Science Foundation of China’s "Research on the Macro and Mesoscopic Fragmentation Mechanism of Jointed Rock Masses under the Action of Hobs and the Breaking Efficiency(51879016)",this paper aims at the problem of the rock breaking mechanism by gauge cutter,and combines rock mechanics and line Elastic fracture mechanics and other theories,digital image related technology and BP neural network prediction and evaluation methods,and different cutter for different joint inclination angles and joint spacing rock mass breaking tests.The mesoscopic crack initiation and propagation characteristics,strain field changes,failure modes,load characteristics and rock breaking efficiency of the rock mass under the gauge cutter are studied.The main research work is as follows:(1)Use self-made gauge cutter with installation angles of 15°、 30°、 45° and 60°to carry out the hob breaking test on jointed rock mass specimens.In the test,a noncontact strain and deformation measurement system was used to monitor the cracking process of the rock mass,and the regulation of crack initiation and propagation on the surface of the jointed rock mass under the action of different cutters was analyzed.(2)The rock mass deformation characteristics,crack propagation mode and cracking properties,and rock breaking mode of the cutter are studied.The concept of "crack growth specific energy" is proposed,and the rock breaking efficiency of the cutter is evaluated from the perspective of crack propagation.(3)Through the rock breaking test of the jointed rock mass with the TBM gauge cutter,the macro-mechanical characteristics of the jointed rock mass have been studied.The load characteristics of different installation angles of gauge cutter intruding into different jointed rock masses are analyzed.Due to the inclination of the installation inclination of the gauge cutter,the lateral force must be considered,and then the effect of the normal force and the side force on the rock breaking of the cutter is analyzed.In addition,the relationship between the rock breaking angle of the rock mass and the average load required for rock breaking by the cutter is analyzed,and the rock breaking mechanism of the gauge cutter is revealed.(4)Based on the multiple non-linear regression equation,combined with the test results of the TBM cutter rock breaking,the calculation formula of the cutter rock breaking specific energy considering the installation angle of the gauge cutter,the joint inclination angle and the joint spacing is obtained.The theoretical values and experimental results of rock breaking specific energy under different cutter installation angles and jointed rock mass conditions are compared and analyzed.(5)Combined with the artificial intelligence BP neural network prediction model,the output variables of the Predictive model are the specific energy of breaking rock,the work done by breaking rock,the penetration depth when the peak load occurs,and the peak load.By using two intelligent evaluation methods of nonlinear regression formula and BP neural network prediction model to compare the specific energy of breaking rock and compare with the test results,the applicable scope of the two intelligent evaluation methods is analyzed.Rock breaking specific energy can be predicted. |
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