Research On Characteristic Of Anti-unbalancing Load In Thrust System Based On Relative Force Coefficient Under Composite Stratum

Shield,as a key engineering equipment that modern tunnels can be formed at one time,play an extremely important role in building subway tunnels to relieve urban ground traffic pressure.However,due to the imperfect design theory of shield thrust system in China,unbalanced loads occur during the tunneling process and the segment is destroyed,which affects the waterproof performance of the tunnel and greatly reduces the service life of the tunnel.Therefore,the research on basic theory of thrust system is the focus of the current shield field.This paper mainly studies the anti-offset characteristics of the shield thrust system.The existing shield thrust system is evenly arranged by dozens or dozens of hydraulic cylinders.Due to the uniform layout of the thrust system,it is not enough to solve the current Excessive eccentric load causes the rupture of the segment.Therefore,this paper proposes a design method of non-uniform layout thrust system based on relative force coefficient.The adaptability of non-uniform layout system based on relative force coefficient in composite stratum,the realization method of non-uniform thrust system and the dissection of different layout systems The three aspects of the stress situation have been studied in detail,and the specific research contents are as follows:Firstly,the stress of shield thrust system during tunneling is analyzed in detail.The analysis shows that under the coupling action of external tunneling resistance,horizontal resistance torque and longitudinal resistance torque,the hydraulic cylinder in the thrust system will produce non-uniform top thrust to overcome external resistance,thus causing the unbalanced load phenomenon of the thrust system.Secondly,in order to reduce the unbalanced load,a non-uniform layout system based on the relative force coefficient is proposed.The optimization problem is solved by Lagrange method and the eccentricity cone model of the non-uniform thrust system is constructed by solving the Lagrange partial differential equation on the principle of minimum variation of the relative force coefficient.On this basis,the dynamic simulation is carried out by ADAMS,and the thrust of each hydraulic cylinder is obtained.The simulation results show that the non-uniform layout of the thrust system has strong anti-unbalancing load characteristics.Then,based on the study of the anti-unbalancing load characteristics of the thrust system,two methods of realizing non-uniform layout are proposed.On the one hand,the non-uniform and adjustable layout can be realized by the new mechanism,on the other hand,the non-uniform and controllable layout can be realized by the hydraulic system control,which provides a good theoretical basis for realizing the non-uniform layout of shield tunneling.Finally,a simulation experiment is conducted to verify that the non-uniform thrust system has good anti-load characteristics in the composite formation.Mainly uses the ANSYS finite element method,the stress analysis was carried out on the tunnel lining segment,homogeneous system respectively,and four partition system and heterogeneous systems under the influence of compound formation,the force of the segment,through the analysis of segment deformation nephogram of stress and strain contours,found under non-uniform distribution,the segment of the minimum deformation,stress is also the most uniform.