基于位移控制的装配式预应力鱼腹梁深基坑应用研究

INNOVATIVE PRE-STRESSED AND PREFABRICATED SUPPORT FOR RETAINING STRUCTURE OF DEEP FOUNDATON PIT WITH DISPLACEMENT CONTROL

基于基坑实测数据,从预应力控制、变形控制和刚度控制3个方面研究装配式预应力鱼腹梁支撑体系(IPS)的工作机理及环境影响程度。结果表明:相比于传统内支撑,IPS作用时施加于围护结构上的预应力在基坑开挖前充分激发被动土压力,使围护结构向坑外变形从而大幅制约向内位移,实测数据显示围护结构整体深层位移小于10mm;同时,IPS以施加预应力提高体系表观刚度的方式限制基坑周边变形,实测地表沉降量均未超过18mm,降低基坑开挖对环境的影响程度;另外,针对传统内支撑应力集中缺陷,IPS通过支撑体系全跨度反作用力予以克服,显示出IPS在深基坑工程中较为广阔的应用前景。

Based on the measured data of the foundation pit, the work mechanism and environmental effect of innovative pre-stressed and prefabricated support（IPS） for retaining structures are studied in three aspects. They include pre-stress control, deformation control and stiffness control. Results show that： Compared with the traditional support, the passive soil pressure is fully motivated by the pre-stress that applied to the retaining structure using IPS before excavation. And the measured data shows that the overall deep displacement of the retaining structure is less than 10mm. At the same time, the IPS is applied to limit the deformation of foundation pit by applying pre-stress to improve the apparent stiffness. Measured surface subsidence is not more than 18mm which show it reduces the impact of excavation on the environment effectively. In addition, aimed at the stress concentration defect of traditional internal support, the IPS overcomes it through the support system full span reaction. The IPS indicates wide application in deep excavation engineering.