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以港珠澳沉管隧道天然地基段某一横断面为研究对象,对垫层厚度1 m及1.5 m的工况分别进行了模拟整个施工过程的离心模型试验及有限元计算研究,揭示了不同垫层厚度地基回弹再压缩应力应变特性、沉管结构的应变特征,为沉管隧道的施工及地基处理方案设计提供依据。结果表明,开挖卸荷基底产生拱形回弹;回填后基底应力及沉管底板应变均呈马鞍形分布;随时间及回淤增加,仅基底中部应力增大。垫层薄,基底应力分布匀化效果差,再压缩量及工后沉降增大。
Taking a cross section of a natural subgrade of Hong Kong-Zhuhai-Macao immersed tunnel as a research object, centrifugal model tests and finite element calculations of the entire construction process were carried out respectively for working conditions of cushion thickness of 1 m and 1.5 m, The stress and strain characteristics of rebound and recompression on the cushion thickness and the strain characteristics of the immersed tube structure provide the basis for the design of immersed tunnel construction and foundation treatment scheme. The results show that the basement unloading excavation has arched springback; the stress of basement and the distortion of immersed tube floor have saddle-shaped distribution after backfilling; and the stress increases only in the middle of the basement with the increase of time and siltation. The cushion is thin, the effect of homogenization of the stress distribution in the base is poor, the amount of recompression and post-construction settlement increase.