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盖挖逆作深基坑围护结构变形分析与预测

Analysis and Prediction of Deformation of Enclosure Structures for Cover Reverse Construction Excavation Deep Foundation Pit

  • 摘要: 深基坑围护结构变形控制是施工安全的关键,为研究盖挖逆作深基坑围护结构的变形规律并预测后续施工变形,以武汉轨道交通中一路地铁车站为工程背景开展研究。针对顶板施工(工况1)、恢复路面(工况2)、负1层施工(工况3)、负2层施工(工况4)和底板施工(工况5)5个关键工况,本文采用ABAQUS软件建立车站深基坑三维有限元模型,并结合现场监测数据对模型进行验证;进而分析盖挖逆作深基坑围护结构变形规律,对后续工况变形进行预测。研究结果表明:工况1的数值模拟与实测结果绝对误差均在1 mm以内,相对误差均在15%以内,且两者变化趋势一致、吻合良好,验证了所建有限元模型具有较高的计算精度,可用于后续工况深基坑围护结构变形预测,分析不同施工阶段围护结构的变形特点;后续工况2~工况5中,CX35和CX51测点最大水平位移分别在10.38 mm~20.68 mm和11.76 mm~20.58 mm之间,均低于预警阈值30 mm,处于安全可控状态。所建立的有限元模型可用于后续工况深基坑围护结构变形预测,研究结论可为类似工程围护结构变形分析与预测提供参考。

     

    Abstract: The control of deformation in deep foundation pit retaining structures is crucial for construction safety. To investigate the deformation patterns of retaining structures in deep foundation pits constructed using the cover-excavation reverse construction method and to predict subsequent construction deformations, a study was conducted based on the Zhongyi Road subway station project in Wuhan. Focusing on five key construction stages—roof slab construction (Stage 1), road surface restoration (Stage 2), negative first floor construction (Stage 3), negative second floor construction (Stage 4), and base slab construction (Stage 5)—a three-dimensional finite element model of the station's deep foundation pit was established using ABAQUS software and validated against field monitoring data. Subsequently, the deformation patterns of the retaining structures in the cover-excavation reverse construction deep foundation pit were analyzed, and the deformations under subsequent construction stages were predicted. The results indicate that for construction stage 1, the absolute errors between the numerical simulations and the measured results are all within 1 mm, and the relative errors are within 15%. Furthermore, the trends of the simulation and measured data are consistent and exhibit good agreement, verifying the high computational accuracy of the established finite element model. This model can therefore be used to predict the deformation of deep foundation pit retaining structures in subsequent construction stages and to analyze the deformation characteristics of the retaining structures at different construction phases. For subsequent construction stages 2 to 5, the maximum horizontal displacements at monitoring points CX35 and CX51 range from 10.38 mm to 20.68 mm and 11.76 mm to 20.58 mm, respectively, both remaining below the warning threshold of 30 mm, indicating a safe and controllable condition. The established finite element model can be effectively applied to predict the deformation of deep foundation pit retaining structures in subsequent construction stages, and the findings of this study can serve as a reference for the analysis and prediction of retaining structure deformation in similar engineering projects.

     

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