基坑工程中冠梁刚度的计算方法研究

Research on the Calculation Method of Top Beam Rigidity in Foundation Pit Engineering

针对目前基坑设计中存在冠梁刚度计算偏大的问题,开展了冠梁刚度计算方法的研究。首先对现行商业软件中冠梁刚度计算模型进行分析,然后讨论了简支梁受均布荷载和两端固定梁受均布荷载的冠梁刚度计算模型,并给出了相应的刚度计算公式。考虑了圆形基坑和多边形基坑,推导了圆形基坑冠梁刚度的理论计算公式,并将多边形基坑的冠梁刚度与有限元计算的精确解进行了对比。结果表明:简化模型计算的冠梁刚度误差与基坑形状密切相关,因此不宜直接使用简化模型进行计算。相反,将完整的基坑冠梁作为研究对象,在冠梁上施加荷载,求解对应位移,然后根据刚度计算原理得出冠梁的等效刚度是一种可行和可靠的方法。

In response to the problem of overestimated stiffness calculation in foundation pit design,research on the calculation method of crown beam stiffness is carried out.Firstly,the current commercial software models for crown beam stiffness calculation are analyzed.Then,the crown beam stiffness calculation models of simply supported beam under uniformly distributed load and fixed beam with uniformly distributed load are discussed,and the corresponding stiffness calculation formulas are provided.Considering both circular and polygonal foundation pits,the theoretical calculation formula for crown beam stiffness of circular foundation pits is derived,and the crown beam stiffness of polygonal foundation pits is compared with the exact solution obtained from finite element analysis.The results show that the error of crown beam stiffness calculation using simplified models is closely related to the shape of the foundation pit,therefore it is not suitable to directly use simplified models for calculation.On the contrary,treating the complete crown beam of the foundation pit as the research object,applying loads on the crown beam,solving the corresponding displacements,and then obtaining the equivalent stiffness of the crown beam based on the stiffness calculation principle is a feasible and reliable method.