双线盾构多因素引起地下管线的附加荷载研究

研究了地下管线与双线盾构垂直时地下管线附加荷载的分布规律。采用弹性力学Mindlin解,推导出双线盾构在掘进过程中多因素引起的土体附加应力计算公式。基于Winkler土体模型,推导出双线盾构施工中土体损失引起的竖向土体附加应力计算公式。算例分析结果表明:双线盾构施工中盾壳摩擦力和盾尾注浆压力引起的地下管线附加荷载较大;正面附加推力引起的附加荷载较小;土体损失是引起竖向附加荷载的主要原因;随着先行、后行盾构开挖面前后距离Q的减小,后行盾构上方管线的附加荷载变化比较明显;随着先行、后行盾构轴线水平间距L的增大,x和z方向的附加荷载峰值减小。

Study on Additional Load on Underground Pipelines Caused byMulti-factor of Double-line Shield Tunnels

The distribution regularity of total additional load on perpendicularly crossing buried pipeline induced by double parallel shields construction is studied. The calculation formulas of soil additional stress, which is induced by bulkhead additive thrust, frictional force between shield and soil and grouting pressure, are derived from Mindlin solution in elastic mechanics at the end of the shield during double parallel shields excavation. On the basis of the Winkler model, the calculation formula for vertical additional stress in soil caused by soil excavation is derived. The analytical results show: the additional load of underground pipeline caused by the frictional force and the pressure of shield tail grouting in double line shields construction is large, while the additional load caused by bulkhead additive thrust is relatively small. Soil excavation is the main cause of the vertical load. The additional load on underground pipeline above the second shield changes obviously as the distance Q between the excavation faces of the first and second shield tunnels reduces. The peak values of the additional load on the pipeline in x and z directions reduce as the parallel distance L between the first and second shield tunnels increases.