特殊环境下盾构吊装下井的基坑安全稳定性分析及检算方法研究

Safety analysis of deep foundation pit and check-up method for shield lifting scheme under the special environment

以深圳地铁11号线前海湾站基坑工程为研究背景,大型盾构需要在盾构井的结构未完成状态下进行吊装,结合现场监测、二维和三维有限元数值分析,对特殊环境下盾构提前吊装下井时基坑的安全稳定性进行分析,同时提出一种合理的二维检算方法。研究结果表明:通过对结构楼板约束等效、冠梁刚度折减和土体参数等的合理确定,采用二维模型检算方法可以得出合理、准确的结果。研究结果为特殊环境下大型盾构顺利下井、基坑的安全提供了可靠的技术支撑,所提出的二维检算方法可有效指导同类工程施工技术方案的制定。

On the background of foundation pit of Qian Hal - wan railway station in Shenzhen subway line 11, shield lifting scheme should be determined under the condition of unfinished major structure in shield well due to the complex factors. To solve the complex problem accurately and reasonably, research programs were proposed by combing with field monitoring, 2D and 3D finite element numerical analysis. Firstly, stability and safety of the foundation pit was analyzed under the special environment; Secondly, a practical design method was pro- posed. The research results indicate that 2D model method can obtain the reasonable and accurate results through determining the equivalent constraint model of structure floor, stiffness of top beam, and soil parameters. The so- lutions provide a reliable technical support for large shield lifting under special circumstances; moreover, the proposed practical method can effectively guide the construction scheme for similar engineering programs.