深基坑开挖条件下抗拔单桩承载力性状研究

通过对基坑工程坑底工程桩桩顶位移与桩身轴力的实测结果进行分析总结,发现坑底工程桩在基坑开挖后,由于土体卸荷回弹产生较大的桩顶位移与拉力。为研究深基坑开挖条件下抗拔单桩承载力变化特性,采用有限元分析软件ABAQUS,建立二维轴对称模型,对不同桩长、桩距、开挖深度与开挖半径对坑底抗拔单桩承载力的影响进行了分析。研究结果表明,桩长和桩径可以显著影响开挖后抗拔桩承载特性,可以通过增加桩长与桩径提高抗拔单桩承载力;开挖深度和开挖宽度共同影响坑底抗拔单桩承载力,主要影响基坑开挖后桩体受力特性,对单桩承载力影响较小。因此,当基坑开挖宽度和开挖深度确定后,合理的选择桩长与桩径十分必要。

Research on Capacity Characteristics of Single Tension Pile under Deep Foundation Pit Excavation

The measured data of pile top displacement and pile shaft axial force of the bottom pile in the deep foundation pit engineering were analyzed. It’s found that because of soil unloading and rebound, the bottom pile has a larger top displacement and the axial force after the foundation pit excavation. For the research of single uplift pile bearing capacity variation characteristics under deep foundation pit excavation, two-dimensional axisymmetric model was built by using finite element software——ABAQUS, and the influence of pile length, pile diameter, excavation depth and excavation radius on the single uplift pile bearing capacity was analyzed. The results show that the pile length and pile diameter have a significant impact on the uplift pile’s bearing characteristics after excavation, so the uplift bearing capacity of single pile can be increased by enlarging the pile length and pile diameter. The excavation depth and radius influence the stress characteristics of single uplift pile together. They mainly have effect on pile stress characteristics after excavation, and have little influence on the uplift bearing capacity of single pile. Therefore, when the excavation radius and depth are determined, reasonable choice of pile length and diameter is very necessary.