软弱泥岩大直径盾构姿态失稳与处理措施研究

Posture Destabilization and Treatment Measures of Large Diameter Shield in Soft Mudstone

为解决某大直径盾构在软弱泥岩复合地层曲线段掘进过程中遇到的“滚动”和“栽头”问题,通过分析盾构掘进中姿态失稳的原因和纠偏中常用的方法及对应的纠偏原理,并结合现场实际纠偏过程分析了各纠偏措施的效果,总结了适用于盾构滚动失稳的姿态纠偏技术。结果表明:(1)盾构在软硬复合地层掘进时,地层环境变化复杂容易导致盾构姿态失稳,长曲线段掘进将加剧盾构姿态失稳;(2)增设径向油缸、盾构刀盘单向转动、增添钢楔子等纠偏措施有助于改善盾构滚动。调节油缸压力、增设纵向油缸以及壁后二次注浆有助于盾构“栽头”的调整;(3)注入油脂和膨润土、换刀以及涂抹黄油等辅助方案,有利于降低盾构在姿态调整时的约束;(4)类似于盾构“栽头”与“滚动”同时发生的失稳情况,纠偏过程中建议先解决盾构滚动纠偏后,再解决轴线偏移问题。

In order to solve the "rolling" and "cutterhead pitch" problems encountered by a large diameter shield machine in the process of tunnelling in the curved section of the soft mudstone composite stratum, by analyzing the causes for the attitude destabilization of the shield tunnelling, the commonly used methods in the deviation correction and the corresponding correction principles, the effects of various correction measures are analyzed in combination with the actual correction process on site, and the posture correction technology applicable to the rolling destabilization of the shield. The results show that:(1) When the shield tunnelling is implemented in the soft and hard composite stratum, the complex changes of the stratum environment will easily lead to the instability of the shield posture, and the tunnelling in the long curve section will aggravate the instability;(2) Such corrective measures as adding radial oil cylinder, one-way rotation of shield cutterhead, and adding steel wedge are helpful to improve shield rolling. Adjusting the pressure of the oil cylinder, adding longitudinal oil cylinder and secondary grouting behind the wall are helpful to the adjustment of the shield from "cutterhead pitch";(3) Auxiliary schemes such as grease and bentonite injection, tool change and butter application are conducive to reducing the constraint of the shield during posture adjustment;(4) For the case similar to the simultaneous instability of "cutterhead pitch" and "rolling" of the shield, it is recommended to first solve the rolling correction of the shield before the problem of axis shifting.