排桩内支撑支护结构深基坑冠梁侧压力分布分析

Analysis on Lateral Pressure Distribution of Crown Beam of Row Pile Inner Bracing Supporting Structure of Deep Foundation Pit

冠梁在侧压力作用下,基坑支护结构将产生不同于刚性挡墙的水平位移,特别是在有支撑的基坑,将产生拱现象,引起土压力重新分布,因此传统设计中采用的矩形均布荷载分布形式不符合工程实际情况。结合武汉市某深基坑排桩内支撑支护工程现场监测数据与现象,总结出内支撑系统的冠梁位移变化规律;利用ANSYS有限元软件,运用平面整体分析法对内支撑平面框架进行数值模拟计算,计算时考虑了位移对土压力分布的影响。结合现场监测数据和现象,得出结论:采用梯形分布形式对支撑系统进行设计相对合理,而采用传统矩形分布形式进行设计偏于不安全,采用三角形分布形式进行设计则偏于保守。

For the crown beam under the lateral pressure,the supporting structure of foundation pit will produce the horizontal displacement different from the rigid retaining wall.Especially in the foundation pit with the bracing,the arch phenomenon will produce,which will lead to the redistribution of soil pressure.Therefore,the rectangular uniform load distribution pattern used in the traditional design does not conform to the actual engineering situation.Combined with the field monitoring data and the phenomenon of a deep foundation pit row pile inner bracing supporting project in Wuhan,the change law of the displacement of the crown beam of the inner bracing system is summarized.By using ANSYS finite element software,the numerical simulation of the plane frame of inner bracing is carried out by using the plane integral analysis method.The effect of displacement on the distribution of soil pressure is considered during the calculation.Combined with the field monitoring data and phenomena,the conclusion is that it is relatively reasonable to use the trapezoid distribution form for the design of bracing system,and it is not safe to use the traditional rectangular distribution form for the design.And it is conservative to use the triangular distribution form for the design.