Study On Adhesion Between Clay And Shield Cutter Head

The close face type shield is widely used in tunnel construction in China.In the process of shield tunneling,the cutter head,as a mechanical part of cutting soil,ensures its normal operation,which is the premise of efficient shield tunneling.Cutter head in the working period,often cut down the fine particles,debris re adhesion in the center of the cutter head or open area and the formation of solid,semi-solid block so that the cutter head can not work properly,So it is very important to study the adhesion between clay and cutter head.Through laboratory tests and numerical simulation methods,this paper explores the influence of various factors on the adhesion between clay and shield cutter head.The main contents and results are as follows:(1)A clay-contact surface adhesion tester was independently designed.Two typical clays,montmorillonite and illite,were selected,and a variety of influencing factors(consistency index,temperature,confining pressure,shear rate,drainage environment)were set to analyze the relationship between the clay-contact surface adhesion and other influencing factors(mainly temperature).The results show that the temperature of clay is positively correlated with the adhesion of clay-contact surface in the drainage environment,while the temperature of clay is negatively correlated with the adhesion of clay-contact surface in the undrained environment.The change of temperature has a great influence on the clay-interface adhesion when Consistency index=0.5-0.8.Temperature change has the same effect on clay-interface adhesion under different confining pressures.(2)The relationship between the microscopic parameters of the discrete element and the cohesion of the soil sample,the Angle of internal friction and the adhesion of the claycontact surface were analyzed,and the regression equations between them were obtained by using the response surface method.The three regression equations can be used to calculate the corresponding discrete element microscopic parameters in the range of cohesion 4.19-69.89 k Pa,internal friction Angle 14.27-36.61 °,and adhesion force 14.30-72.21 k Pa.(3)Through numerical simulation,the paper analyzes the relationship between temperature of soil,cutting wheel rotation speed and the shield machine tunneling cutterhead torque,the knife dish positive resistance,the knife dish plane particle movement,shield machine driving in front of the particle movement.The results show that under the undrained condition,the peak torque,the stable torque and the knife dish positive resistance all decrease non-linearly with the increase of the excavation particle temperature.Within a certain range,the peak torque of the cutter head increases nonlinearly with the increase of the cutter head speed,and the knife dish positive resistance decreases non-linearly with the increase of the cutter head speed.The influence range of cutter head rotation on the soil movement in front of the excavation is less than 1/10 of the width of the diameter of the shield cutter head.Finally,the rationality of the calculation result is proved by an engineering example.