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

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.