Influence of Double-O-Tube Shield Rolling on Soil Deformation during Tunneling

Abstract

One of the main disadvantages of the advanced tunneling technology of the double-O-tube (DOT) shield is unavoidable rolling of the shield machine during construction. In this study, the influence of the DOT shield rolling on soil deformation during tunnel construction was analytically investigated. Based on the generalized Sagaseta’s solution, the equations for calculating vertical and horizontal soil deformations due to DOT shield tunneling–induced ground loss caused by shield rolling were derived. The theoretical results show that the deformation field of the surrounding soil is obviously changed from symmetry to asymmetry, and the maximum deformation increases observably with rolling. In the case of different rolling angles of the DOT shield, on any horizontal plane in the range of the burial depth of the shield top, an interesting rule was found where the vertical deformation curves have a focal point, whereas the horizontal deformation curves hold two focal points at which the corresponding deformation is constant with rolling. The balanced point of horizontal deformation, at which the horizontal deformation is zero and the maximum settlement occurs, moves gradually toward the rolling side with rolling. These findings from the analytical investigation provide a reliable background in predicting the soil deformation induced by DOT shield tunneling.