盾构俯仰角变化对盾构-土相互作用影响研究

盾构姿态改变过程中盾构-土相互作用是复杂的多相耦合问题。针对盾构俯仰角这一关键姿态参数,基于地基反力曲线,通过等效土体弹簧简化了盾构-土相互作用关系,从而建立了盾构-土相互作用模型。通过改进的Terzaghi松动土压力计算方法,解决了盾构-土相互作用初始边界问题。基于以上研究成果,得到了盾构俯仰角理论计算方法,并对垂直基床系数以及上软下硬地层等因素对盾构-土相互作用的影响进行了分析和讨论。结果表明:上软下硬地层不利于盾构姿态的控制,对于盾构姿态控制的要求更高。最后,结合济南地铁R2线盾构隧道工程对俯仰角的实测数据进行了对比分析,结果表明,由于千斤顶施加的偏转弯矩无法完全作用于盾构,导致实测值普遍略小于理论值。盾构俯仰角的理论计算方法可为盾构姿态控制提供理论指导。

Influence of shield pitch angle variation on shield-soil interaction

Shield-soil interaction is a complex multiphase coupling problem during the change of shield attitude. According to the critical attitude parameter of the shield pitch angle, based on the ground reaction curve, the shield-soil interaction relationship is simplified by using an equivalent soil spring, and a shield-soil interaction model is established. The initial boundary problem of shield-soil interaction is solved by the improved method of the loosening earth pressure of Terzaghi's theory. A theoretical calculation method of shield pitch angle is further obtained. Moreover, the effects of the vertical coefficient of subgrade reaction and upper-soft lower-hard ground on shield-soil interaction are analyzed and discussed. The results show that the upper-soft lower-hard ground is unfavorable to the control of the shield attitude, and the requirements for shield attitude control become high. Finally, the measured data of the pitch angle of the R2 line shield tunnel project of Jinan Metro are compared and analyzed. The results show that the deflection moment applied by the jacks cannot fully act on the shield, resulting in the measured values are generally slightly smaller than the theoretical value. The theoretical calculation method of shield pitch angle can provide theoretical guidance for shield attitude control.