Abstract: The risk of cracking and longitudinal dislocation of the shield tunnel segment could be reduced by minimizing the pressure deviation of each partition during the posture control of the shield. To realize equalization allocation, a geometric model is constructed and the partition hydraulic constraint is deduced. Based on the targeted thrust and moment conditions, a partition hydraulic pressure calculation formula that could realize the equalization allocation for many partition hydraulics is derived. Comparative validation results indicate that compared with the traditional pseudo-inverse method and manual allocation method, the proposed equalization method effectively improves the equalization of the allocation results and significantly reduces the pressure deviation between adjacent partition hydraulics. Based on the equalization principle, the moment/center of thrust limit boundary solution method corresponding to different thrusts is proposed, and the corresponding laws are described: with the increase of the thrust from 0 to the critical value, the limit moment in the same orientation increases linearly from 0 to its maximum while the radius of the limit center of thrust is a fixed value; as the thrust gradually increases to the maximum from the critical value, the limit moment linearly decays from the maximum to 0, and the limit center of thrust nonlinearly decays from the maximum to 0. Based on the limit boundaries, the control risk caused by the moment/center of thrust setting exceeding the boundaries can be avoided. This provides a theoretical basis for the equalization allocation of partition hydraulic pressures and moment parameter setting of the shield and automatic control of shield posture.

Key words: shield, partition hydraulic pressure, equalization control allocation, moment extremes, boundary of thrust center