Study on the Stability of Ultra-Small Radius Curved Beam Bracket System in Complex Soft Soil Foundation Environment of Fuli Expressway
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摘要: 针对复杂软土地基环境下超小半径曲线梁支架系统施工的安全问题,以阜溧高速大纵湖互通C匝道桥工程为背景,采用有限元软件MIDAS/Civil建立支架系统模型,研究了复杂软土地基环境下曲线梁支架系统稳定性问题,分析了软土地基不均匀沉降、曲线梁曲率半径及支架跨度、宽度、高度等因素对支架系统力学性能的影响。结果表明:在软土地基不均匀沉降影响下,支架1和支架2失稳破坏时的水平杆最大应力分别为82.32,127.36 MPa,水平杆均未达到屈服状态,支架失稳由立杆自身刚度不足引起;在梁体混凝土达到一定强度时,支架屈曲荷载随着曲线梁曲率半径增大而增大,120 m曲率半径时,支架屈曲荷载比60 m曲率半径时增大了93%;支架宽度、高度对支架稳定性有较大影响,增大支架横向宽度和减小支架高度会提高支架稳定性,与支架宽度为16.5 m相比,宽度为22.5 m时支架屈曲荷载提高了62.34%。依据研究成果对支架系统进行沉降监控,现场监测显示,支架沉降监测数据均在规定范围内,表明软土地基环境下支架法施工有良好的可行性和安全性。Abstract: Aiming at the construction safety of ultra-small-radius curved beam bracket system under complex soft soil foundation environment, taking the Dazonghu Interchange C-ramp bridge project of Fuli Expressway as the background, the finite element software MIDAS/Civil was used to establish the bracket system model, the stability problem of curved beam bracket system under complex soft soil foundation environment was studied. The influence of uneven settlement of the soft soil foundation, curvature radius of the curved beam, and bracket span, width, and height on the stability of the bracket system was analyzed. The results show that under the influence of uneven settlement of the soft soil foundation, the maximum stresses of the horizontal rods when bracket 1 and 2 lose stability are 82.32 MPa and 127.36 MPa, respectively, and none of the horizontal rods reaches the yield state. The instability of the bracket is caused by the insufficient stiffness of the pole itself. When the concrete of the beam body reaches a certain strength, the buckling load of the bracket increases with the increase of the curvature radius of the curved beam, and the buckling load of the bracket of the 120 m curvature radius increases by 93% compared with that of the 60 m curvature radius. The width and height of the bracket have a great influence on the stability of the bracket. Increasing the lateral width of the bracket and reducing the height of the bracket will improve the stability of the bracket. Compared with the bracket width of 16.5 m, the buckling load of the bracket width of 22.5 m increases by 62.34%. Based on the research results, the sedimentation monitoring was conducted on the bracket system, and on-site monitoring showed that the bracket sedimentation monitoring data were within the specified range, indicating that the bracket method has good feasibility and safety for construction under soft foundation conditions.
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