Analysis of double-O-tube shield tunnelling-induced soil deformation due to ground loss

Abstract

The ground loss distribution caused by double-O-tube (DOT) shield tunnelling is more complex than that caused by single circular tunnelling. An analytical solution was presented for soil deformation due to ground loss induced by DOT shield tunnelling. On the basis of construction characteristics, a model of DOT shield tunnelling-induced ground loss was produced by modifying the oval-shaped model of ground loss used for single circular tunnelling. Meanwhile, the soil deformation caused by unit ground loss was obtained. By means of integrating over the region of ground loss, the soil deformations induced by DOT shield tunnelling including settlement and horizontal deformation were predicted through this proposed solution. The surface settlements calculated by this solution compared favourably with the field records and the results from the superposition method and the equivalent excavated area method. It was found that this proposed solution was in better agreement with the field data. In addition, the extensional analyses of settlement, horizontal deformation, and contours and vectors of soil deformation around the DOT shield tunnel were also carried out.