Abstract: To improve the utilization rate of existing conventional shield machines and align with China′s sustainable development strategies in underground engineering, the authors propose a micro-transformation scheme for retrofitting the automatic tunneling attitude control function of existing shield machines. The approach is contextualized within a shield tunneling project in the Shanghai metro. The system architecture is designed, and thrust distribution calculations are performed in different propulsion zones, enabling a cross-diameter and cross-mode engineering application of a thrust vectoring adaptive control method for shield attitude regulation. The following conclusions are drawn: (1) The execution of target oil pressures in the propulsion zones, based on target thrust vector distribution, achieves a control accuracy within ±5%. (2) To maintain consistent and uniform advancement capability, the target thrust is controlled approximately 3% higher than the actual thrust, with the shield speed controlled within ±3 mm/min of the set value. (3) The interaction characteristics between changes in shield attitude and the displacement of the thrust vector action point exhibit a mirror-symmetrical relationship, with over 98% of the total segments maintaining horizontal and vertical attitude control within the target range of ±10 mm across individual sections.

Key words: existing shield machines, intelligent transformation, automatic tunneling, thrust vector, engineering application