Abstract:

The post-construction long-term settlement of a large cross-section small-spacing pipe jacking tunnel in soft soil is predicted and analyzed to ensure its safety and stability during construction and operation. The two-dimensional numerical analysis method with the soft soil creep constitutive model is used to establish an analysis model for the longterm settlement of the combined pipe jacking structure; and the development of the long-term settlement of the surface, combined pipe jacking structure and soil is analyzed. The analytical results show that: (1) The long-term settlement of surface and combined pipe jacking structures develops fast in the early stage, but slows down with time; and the time for stabilization is quite long. (2) The long-term settlement of the surface is large in the middle and small on sides, and the maximum settlement value is 28. 4 cm in 20 years. (3) The long-term settlement of the east line station and that of the west line station are relatively coincide with each other, the settlement value is 8. 9 cm, and the settlement of west line station hall, in contrast, is significant and the settlement value reaches 22. 4 cm.

Key words: soft soil layer, combined pipe jacking structure, soft soil creep model, long-term settlement