复合地基中桩帽作用数值分析及桩帽承载力计算

摘要

Using three-dimensional Fast Lagrangian Analysis of Continua and depending on the geological, design and construction conditions of some testing sections in certain subgrade engineering, the numerical analysis model for rigid-pile composite foundation with pile cap under embankment load is established and the influence of diameter variation of pile cap on the settlement of rigid-pile composite foundation is analyzed. The result shows that the increased diameter of pile cap can play the role of enhancing the load sharing ratio of piles and reducing the total settlement of the composite foundation and the settlement difference between piles and soil ; and the diameter variation of pile cap has little influence on the settlement of underlying layer. According to the research results in related documents, the calculation method of bearing capacity for plain concrete circular-plate pile cap and inverse cone-frustum pile cap under embankment load is established, which is verified for reliability with examples. The research result can be referred to in the design of plain concrete pile cap in rigid-pile composite foundation under embankment load.%采用三维快速拉格朗日分析程序，依据某路基试验段的工程地质和设计施工情况建立了路堤荷载下带桩帽刚性桩复合地基数值分析模型，分析了桩帽直径变化对刚性桩复合地基沉降的影响，结果表明：桩帽直径的增大能够起到提高桩荷载分担比、减小复合地基总沉降和桩土沉降差的作用，桩帽直径的变化对下卧层沉降的影响较小。根据相关文献的研究成果，建立了路堤荷载下素混凝土圆板桩帽和倒圆台桩帽的承载力计算方法，并结合实例验证了承载力计算方法可靠性。研究成果可为路堤荷载作用下刚性桩复合地基中素混凝土桩帽的设计提供参考。