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沉管隧道在开挖及回填过程中基底应力分布特征及其与沉管结构的变形特性分析在隧道工程中占重要地位。通过以港-珠-澳沉管隧道天然地基段某一横断面为研究对象,对整个施工过程进行不同垫层厚度的离心模型试验及有限元计算模拟,揭示沉管隧道天然地基开挖回弹及回填再压缩应力分布及变形特征、沉管结构的应变特征及垫层厚度对其影响,为沉管隧道的施工及地基处理方案设计提供参考。结果表明,开挖卸荷使基底产生拱形分布回弹。回填后基底应力呈马鞍形分布,仅中间部分应力随时间及回淤增加而增大;沉管底板应变呈马鞍形分布,工后应变量变化不大。垫层厚度变薄使基底应力分布匀化效果差,回填再压缩量及工后沉降量变大。
The stress distribution of foundation in the process of excavation and backfilling tunnel immersed tunnel and the analysis of the deformation characteristics of the immersed tunnel structure occupy an important position in tunnel engineering. Taking a certain section of the natural ground segment of Hong Kong-Zhuziliao-Macao Immersed Tunnel as the research object, the centrifugal model test with different cushion thickness and the finite element calculation are carried out to reveal the rebound of the natural foundation excavation of the immersed tunnel And stress distribution and deformation characteristics of backfill and re-compression, the strain characteristics of pipe sinking structure and the influence of cushion thickness on it, which provide reference for the construction of immersed tunnel and the design of foundation treatment. The results show that the excavation unloading makes the basement arched distribution rebound. Backfill after the substrate stress saddle-shaped distribution, only the middle part of the stress increases with the increase of silt and back; immersed tube floor saddle-shaped strain distribution, after the change in the amount of work is not. The thickness of the cushion becomes thin so that the stress distribution of the substrate is poorly homogenized, the amount of backfilling and the amount of post-construction settlement become larger.