Estimation of transverse ground surface settlement induced by DOT shield tunneling

摘要

Double-O-Tube (DOT) shield tunneling has attracted increasing attention because it offers cost-efficiency in underground construction. Prediction of DOT shield induced ground surface settlement is crucial to underground construction in densely populated urban areas since excessive settlement could trigger potential damage to existing structures. Hitherto, there have not been many studies on this aspect, as only three regions: Japan, Shanghai and Taipei have adopted this tunneling technique. The transverse ground surface settlements induced by the closure of tail void of a DOT shield that formed a portion of the Taoyuan International Airport Access Mass Rapid Transit system in Taipei have been used and back-analyzed using the empirical equation that assumed the settlement profile over a tunnel to be a Gaussian distribution curve and the finite element (FE) analysis. The results showed that the ground surface settlement trough of the DOT tunnel could be conveniently and reliably estimated using the empirical equation, while the FE simulated result was unsatisfactory. Nevertheless, the FE simulation revealed that the ratio of the maximum ground surface settlement to the depth of tunnel axis is linearly proportional to the stress reduction ratio of the ground.