This paper is to investigate the mechanical characteristics of non-equidistant thrust system in an EPB shield machine with a diameter of 6.15 m applied in Beijing Metro Line 6 construction. Firstly, on the ground of tunneling condition, virtual prototypes for traditional even system and the non-equidistant one have been built. Under the same given working conditions, simulation forces from three jacks in two systems have been compared with those numerical ones. Secondly, based on relative coefficient mode, comparison of force transmission performance between traditional even thrust system and the non-equidistant one have been discussed. Finally, the effects from all forces applied by the two kind of different layouts thrust systems have been studied using finite element method. The results shown that the non-uniform thrust system in the EPB shield machine applied in Beijing subway construction has more significant advantages in the aspects of forces transmission performance and the prevention of the collapse of the lining segments.

Based on the engineering challenge of dynamic stability control for shield propulsion systems under complex geological conditions, this study aims to address two critical issues: adaptive optimization of nonuniform configurations during multi-ring continuous tunneling and long-term stability evaluation. By establishing a segmented progressive reconfiguration mechanism with the core constraint of minimizing phase angle adjustment quantities between adjacent configurations, analytical optimization algorithms achieve rapid and energy-efficient switching of nonuniform layouts. Simultaneously, this work innovatively proposes the Thrust Stability Coefficient ( TSC ). A quantitative dynamic stability evaluation model is developed by coupling the discrete characteristics of thrust variation coefficients with their mean levels. Numerical simulations and field validation demonstrate: The nonuniform thrust system reduces TSC values by 85%, while the overall TSC at the Duesseldorf WHL Metro Project in Germany is further reduced by 70% during continuous construction. Adams virtual prototype simulations validate the effectiveness of TSC in characterizing the stability of chained nonuniform configurations. The theoretical framework of “dynamic reconfiguration optimization—global stability evaluation—long-term safety control” established in this research not only provides innovative solutions for shield propulsion systems under complex geological conditions, but also delivers critical technical support through its engineering data-driven verification methodology and chain optimization strategy for the stability control of intelligent tunneling equipment in underground engineering.

This work aims to investigate the force transmission characteristics of a thrust system in a rectangular shield machine under the influence of various factors. These factors main include the external partial loads produced by the heterogeneity of rock and soil on the excavation face, the uneven distribution of friction acted on the shield body of the shield tunneling machine, the uneven distributed mass of the main machine, or attitude correction in the tunneling construction progress. First, the force uniformity mechanical model for the rectangular shield machine has been set up on the basis of the external loads. The force transmission characteristics of the model for the thrust system have been discussed in detail. Then, the method of reconfiguring the hydraulic cylinders in the thrust system to improve the force transmission performance has been proposed. Finally, virtual prototype simulation has been conducted to verify the effectiveness of presented method. Results show that the coefficient variation (CV) value of the reconfigured thrust system is much smaller than that of the unadjusted one, indicating that the force uniformity of the reconfigured thrust system is better. Such results would provide foundation and support for the design of a rectangular shield machine that can avoid partial loads.