Effect of mound removal at airport flight area on existing tunnels

The additional deformations of the tunnel and surrounding soils during adjacent mound removal at a southeastern coastal airport were investigated using finite element software. By comparing different unloading directions and soil sequences, the additional displacement data of soils and tunnel structures under 8 unloading conditions are discussed. According to the simulated results, the principles of tunnel displacement and deformation of the surrounding soils are obtained for determining the optimal construction solutions: (1) The maximum vertical displacement in the unloading area of the lower part of the soils occurs at the center of the surface, and during the unloading process, the vertical displacement of the soils is always greater than their horizontal one. (2) The process of mound removal causes uplift and curvature changes in the tunnel, and the maximum horizontal and vertical displacements of the tunnel are observed at the location closest to the mound.