关键词: 地面出入式盾构法, 土体垂直变形, Mindlin解, 土体损失

Abstract: This paper is to investigate the calculation methods for the soil vertical deformation induced by constructing the ground penetrating shield tunnel. Lin’s formula was also corrected by considering the included angle ? between the axis of the tunnel and the horizontal plane (namely the variation of the buried depth of tunnel). A new formula of soil vertical deformation was derived by combining with bulkhead additive thrust, the friction force between shield and soil, additional grouting force and soil loss. Through analysing the examples, it was found that the results obtained from the new method were entirely different from those of Lin’s formula in a shallowly embedded tunnel. Especially, the results of the ground uplift before the excavation face and the settlement after the excavation face were both larger by the new method. When the shield tunnel excavated upward with the increase of ?, an upwards trend could be seen from the vertical deformation curve of longitudinal soil, which was induced by bulkhead additive thrust, friction force and soil loss. While in the same situation, a downward trend was found from the deformation curve of soil, which was induced by additional grouting pressure. In addition, the maximum value of the surface settlement reduced, whereas the range of the transverse surface settlement trough increased.

Key words: ground penetrating shield technology, soil vertical deformation, Mindlin solution, soil loss