ABSTRACT
Owing to the growing demand for underground expressways in large cities, there are increasingly more cases of super-large-diameter shield tunnels crossing existing tunnels at small spacing. Ground surface settlement caused by shield tunneling affects the normal operation of surface buildings, necessitating a comprehensive investigation. In this study, a parametric analysis was conducted to examine the effects of varying spacing between the new super-large-diameter shield tunnel and the existing tunnel on the surface settlement. Ground surface settlement curves were plotted along the survey lines parallel to the axes of both the new and existing tunnels. The results indicate that the settlement curves along the survey lines parallel to the existing tunnel axis are symmetric, while those parallel to the new tunnel axis are asymmetric. Notably, smaller tunnel spacing correlates with narrower and deeper settlement trough along both groups of survey lines, having a greater impact on the ground.
