双圆盾构隧道施工引起的地面沉降预测

Prediction of surface settlement induced by double-o-tube shield tunnel excavation

将随机介质理论应用于双圆盾构隧道施工引起的地面沉降计算,假定开挖后土体移动模式为不均匀收敛,推导了土体损失引起的地面沉降计算公式。算例分析结果表明:预测结果与实测值比较吻合;双圆叠加模型计算结果明显偏大,原因是没有考虑双圆盾构重叠部分减少的土体开挖面积,仍按两个单圆的土体开挖面积来计算,导致土体损失量比实际大;将双圆叠加模型计算结果按实际土体开挖面积相应折减,发现其计算结果仍比实测值大,表明双圆盾构隧道不能简单地采用两个单圆叠加得到。对双圆叠加模型进行修正,提出修正系数取值,修正后的双圆叠加模型计算值与实测值较吻合。

Stochastic medium theory is first applied to calculate the surface settlement induced by double-o-tube shield tunneling construction. Assuming the soil movement after excavation is non-uniform convergence mode, the calculation formula for surface settlement induced by ground loss is deduced with stochastic medium theory. As shown in analytical calculation, the predicted surface settlements are in good agreement with the observed settlements. The results of double circle overlay model method are obviously bigger compared with the field data. There is no consider the reduction amount of soil loss due to double circle overlap, so the amount of soil loss is much more than the actual. If reducing the double circle overlay model method according to actual soil excavation area, it can be found that the results are still higher than the measured values. It is indicative that the surface settlement induced by double-o-tube shield tunneling can not simply calculate by this method. The modified double circle overlay model method and the modified coefficient are presented. The calculated surface settlements using the modified double circle overlay model method are good accordant with the field observations.