Study On Anti-bias Load Layout Method Of Reconfigurable Thrust System In The Shield Machine Under Complex Strata Conditions

As an important construction equipment for urban underground tunnel construction,shield tunneling machine has been adopted by more and more enterprises in the field of tunnel construction because it plays a more and more important role in solving urban traffic pressure.Although shield tunneling plays a more and more important role in tunnel construction,it still faces some problems in the construction process.For the shield thrust system,due to the complexity and uncertainty of geological conditions in the process of tunneling,the unbalanced load effect for thrust of the hydraulic cylinder is causing the failure or crushing of the rear pipe segment,which is increasingly frequent.In order to solve the above problems,based on the load model of shield thrust system under the condition of composite formation,the uniform force characteristic law of shield thrust system is found.Based on this law,some optimization methods are proposed to solve the unbalanced load effect of circular shield machine and rectangular shield machine.The specific work carried out is as follows:Firstly,the anti-bias load working mechanism of shield thrust system is illustrated.Uniform thrust system in a composite formation condition inevitably exists unbalanced load effect,so through adjusting the layout of shield thrust system to make it adapt to the external loads so as to eliminate or reduce the unbalanced load effect is to become an effective means,and on this basis,two design models of reconfigurable thrust system with adjustable layout for hydraulic cylinders are introduced.Then the load model of shield thrust system under the condition of composite formation is constructed.In order to effectively analyze how the layout of thrust system adapts to the external loads so as to eliminate or reduce the influence of unbalanced load effect,the systematic modeling of the external loads acted on the thrust system in shield tunneling machine is carried out from three aspects: the tunneling load,the transverse resistance moment and the longitudinal resistance moment.Next,the uniform force characteristic law for shield thrust system is found.This law essentially explains how to completely eliminate the unbalanced load effect by adjusting the layout of the hydraulic cylinders in the shield thrust system to adapt to the external loads.According to the guiding principle of this law,it lays a theoretical foundation for further proposing the anti-bias load layout design method to solve the unbalanced load effect of shield thrust system.Finally,an optimization method of anti-bias load layout design of shield thrust system is proposed.The layout design optimization model of deactivated and activated control and the layout design optimization model of displacement control are proposed for the circular shield thrust system.For the rectangular shield thrust system,an optimization model for the anti-bias load layout design of the rectangular shield thrust system is proposed.By adopting the above layout optimization methods,CV value is used as the evaluation index of anti-bias load characteristics of shield thrust system,and the simulation analysis is carried out in ADAMS.The simulation results show that the optimized thrust system compared with non-optimized thrust system has a better performance of anti-bias load characteristic,which can effectively protect the rear segment from rupture or crushing.