Abstract: To solve the challenges in obtaining the target total thrust vector based on the shield posture adjustment requirements during self-adaptive shield axis control in soft soil strata, a shield thrust vector self-adaptive control technology is proposed in this study. Through the closed-loop control combining the total thrust with the shield tunneling speed, as well as the horizontal and vertical moments of the total thrust with the target steering angles in the horizontal and vertical directions, respectively, the fast self-adaptive generation of the total thrust vector under non-constant load is realized. Then, a large-scale testing platform which can simulate shield tunneling along a straight line and a hydraulic system allowing independent control of all propulsion cylinder units is developed. The feasibility of steady-state driving of a shield under non-constant load forces, non-constant load force moments, and non-constant load force vectors is verified. The test results show that: the total thrust effectively responded to changing load force, and the difference between them was maintained to be the frictional resistance of the system, and recovery after slowdown of the shield due to sudden changes of load force was observed; the horizontal posture deviation of shield head could be overshoot and reset after a small sudden change in the event that the total thrust moments of the shield failed to follow up with the changes of the load force moments in time; the total thrust vectors achieved high-quality collaborative response to the load force vectors, with the tunneling speed and the horizontal posture deviation of shield head controlled in the ranges of －1－+2 mm/min and ±3 mm from the set values, respectively.

Key words: shield, shield tunneling; thrust vector, self-adaptive control, test platform