| The terrain conditions in western my country are complex,with numerous mountains and hills.Tunnel construction is facing higher construction difficulties and greater construction risks.Full-face hard rock tunnel boring machine has obvious advantages such as good safety performance,high construction efficiency and low construction cost,and is more and more widely used in the construction of long tunnels.TBM uses hobs to break rock,and its rock breaking efficiency is affected by engineering geological conditions and its own tunneling parameters.In the process of rock-breaking excavation,it is necessary to continuously adjust the excavation parameters to adapt to the current geological conditions of the surrounding rock,and the cutterhead load data fed back by the sensor is the main basis for adjusting the excavation parameters.Therefore,based on a project in Xinjiang Province,this thesis established a rock breaking model of hob through numerical simulation,studied the influences law of rock strength,joint parameters and TBM’s own driving parameters on the cutter head load,and then analyzed the primary and secondary sequence of influences on the cutter head load when all factors acted together,and the multiple linear regression equation which can reflect the influence of multiple factors on cutter head load is obtained by fitting.The work and research results of this thesis are as follows:(1)Rock mechanics parameter determination and modelingThrough the uniaxial compression test and Brazilian splitting test,the rock’s compressive strength,tensile strength,elastic modulus,Poisson’s ratio and other macroscopic mechanical parameters were obtained.The PFC3 D software was used to carry out numerical simulation of uniaxial compression and Brazilian splitting test that matched the size of the laboratory rock sample,and the "trial and error method" was used to calibrate the mesoscopic parameters of the rock sample,and the mesoscopic mechanical parameters required by the hob rock breaking model were obtained.The rock mass is built with spherical particles,and the hob and cutterhead are built with rigid walls.The rock model and the cutterhead model are combined to form the hob rock breaking model in this thesis,and The accuracy of the model was verified by comparing the field measured data.(2)Influence of rock mass strength and joint parameters on cutter head loadBased on the established hob rock breaking model,the influence of rock mass strength and joint parameters on the load of the TBM cutterhead was analyzed.The study found that the load on the cutter head will increase with the increase of rock strength,In the process of rock strength increasing from 46.54 MPa to 160.35 MPa,thrust and torque increase by 298% and 251%,respectively,and the higher the rock strength,the more obvious the fluctuation of the load curve.The addition of joints will not change the shape of the load curve,but the load will increase with the increase of the joint spacing,when the joint spacing is increased from 0.6m to 1m,the thrust and torque increase by 156% and 76% respectively,and the degree of fluctuation will become stronger;the load will decrease with the increase of the joint opening,when the joint opening is increased from 6mm to 10 mm,the thrust is decreased by 22% and the torque is decreased by 28%,and the degree of fluctuation will increase slightly.The load decreases first and then increases with the increase of joint dip Angle,and the fluctuation degree does not change obviously.(3)Influence of TBM tunneling parameters on cutter head loadBased on the established hob rock breaking model,the influence of rotation speed and thrust speed on the load of the TBM cutter head was analyzed.The research found that: with the increase of the rotational speed,the load curve collected under the same excavation distance is denser,but the load value will decrease accordingly,when the speed increases from 3 r/min to 11 r/min,thrust decreases by 20% and torque decreases by 28%,and the fluctuation degree will become weaker;The increase of the pushing speed makes the load curve collected under the same excavation distance more sparse,and the load value shows a trend of increase,In the process of increasing the push speed from 19 mm/min to 27 r/min,thrust increased by 349%,torque increased by 147%,and the degree of fluctuation becomes stronger obviously.(4)Influence of the comprehensive effect of various influencing factors on the cutter head loadTaking joint spacing,joint opening,joint inclination angle,rotating speed and pushing speed as variables,and thrust and torque as evaluation indexes,an orthogonal experiment with 5 factors and 5 levels was designed.The study found that the primary and secondary order of the factors affecting the cutterhead load was thrust speed,rotational speed,joint spacing,joint inclination,and joint opening,and a multiple linear regression equation that could reflect the influence of multiple factors on the cutterhead load was fitted. |
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