软土大断面类矩形组合顶管暗挖车站长期沉降预测分析

为确保软土地层中施工的大断面小间距顶管隧道及车站运营期的安全稳定,针对其工后的长期沉降进行预测分析。采用二维数值分析方法,选用软土蠕变本构模型,建立组合顶管结构长期沉降的预测分析模型,分析地表、组合顶管结构、地层内部土体的长期沉降随时间的发展规律。结果表明: 1)地表和组合顶管结构的长期沉降发展趋势均为前期增长较快,随着时间的发展增长速率减慢,但达到稳定所需的时间较长; 2)地表长期沉降分布为中间大两边小,20 年时间内最大沉降值为28. 4 cm; 3)东线站台层顶管和西线站台层顶管的长期沉降比较统一,沉降值为8. 9 cm,西线站厅层顶管相比之下沉降显著,沉降值达到22. 4 cm。

Prediction and Analysis of Long-term Settlement of Large Cross-section Quasi-rectangular Combined Pipe Jacking Excavated Station in Soft Soil

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.