双圆盾构隧道施工中压重纠偏效果分析

Effect of single side loading on Double-O-Tube shield rolling control

在双圆盾构隧道施工过程中双圆盾构往往会由于以下因素发生侧向偏转:(1)土层分布不均匀;(2)盾构机的制造误差;(3)运输台车的牵引力的不同;(4)已拼装管片的作用;(5)注浆的流失;(6)施工中的不当操作。首先,分析了双圆盾构施工中产生偏转的原因以及纠偏方法,其中单侧压重是纠正双圆盾构侧向偏转的最为简单经济有效的方法。在工程实践中,压重荷载的大小一般取决于操作人员的经验和现场观测偏转角的变化。在单侧压重实施前没有预测其纠偏效果的方法,而且,压重纠偏还会引起周围地层的变位。应用有限元数值模拟的方法,分析总结了压重荷载与偏转角的关系以及双圆盾构周围土层的变形。对于最大允许偏转角为0.6°时,需加压重荷载为350 kN将其纠正。同时,纠偏0.6°偏转角会造成85 mm的额外地表沉降,其结果可供实际工程的施工管理参考。

During double-o-tube DOT tunnel construction, rolling will inevitably occur due to the following reasons： different subsoil condition; manufacturing errors of machine; different pull forces at the two sides; effect of assembled segments; loss of grouts; and operation problems. Several countermeasures to correct rolling have been proposed. Loading using lead block at the elevated side is the most easy and economic method. In engineering practice, the weight of loading is determined by the experience of operating workers and/or through the observation of returned rolling angle. There is no prediction method before loading applying. Moreover, loading correction will also cause additional movement of surrounding ground. This paper analyzes the weight-correcting angle relation and deformation around DOT shield by employing FEM. For the allowable angle of 0.6 degree, the applied load should be 350 kN. Correcting 0.6 degree causes about 85 mm of additional surface settlement. These results can give a guide to the construction management.