王立兴 吴文兵 杨晓燕 张云鹏 王奎华

摘 要：基于虚土桩模型，研究了桩端应力扩散效应对单桩沉降的影响。结合虚土桩模型和Boussinesq解，提出考虑桩端应力泡形扩散的应力泡形虚土桩模型来考虑桩端土对桩的支承作用;利用荷载传递法，对桩周土采用双折线模型，推导得到层状地基中考虑桩端应力泡性扩散的单桩沉降解析解;讨论了弹性极限位移、弹性抗剪切刚度系数、附加应力值等参数对单桩沉降的影响;结合工程实测数据，将该方法与现有理论解进行对比，验证了方法的合理性。应力泡形虚土桩模型的最大优势在于能够较严格地给出桩端应力扩散边界，具有更广泛的工程应用价值。

关键词：单桩沉降;应力泡形虚土桩;层状地基;应力扩散;荷载传递法

中图分类号：TU473.1 文献标志码：A 文章编号：2096-6717（2021）06-0065-09

Abstract： Based on the fictitious soil pile model， the effect of pile-end stress diffusion on the settlement of a single pile has been investigated theoretically. Firstly， a pile-end stress-bubble fictitious soil pile model considering the spread of the pile-end stress-bubble was proposed to simulate the supporting effect of the pile end soil on the pile body by combining the fictitious soil pile model and Boussinesq solution. Then， based on the load transfer method， an analytical solution of single pile settlement considering pile-end stress-bubble diffusion in layered foundation was derived by utilizing the double-broken-line model for the soil around the pile. Furthermore， the effects of parameters such as elastic limit displacement， elastic shear stiffness coefficient and additional stress value on the settlement of single pile were discussed based on the present solution. Finally， combining with the actual engineering data， the present method was validated by comparing with existing theoretical solution. The stress-bubble fictitious soil pile model is more meaningful for engineering applications on account of the obvious advantage that the stress diffusion boundary at pile end can be given more strictly.

Keywords：single pile settlement; stress-bubble fictitious soil pile; layered soils; stress diffusion; load transfer method

樁基沉降计算是桩基工程设计中非常重要的部分。学者们对桩基沉降进行了广泛而深入的研究，得到了很多有价值的单桩沉降计算方法，如荷载传递法[1-7]、剪切位移法[8-10]、弹性理论法[11-13]、规范法[14]和数值计算法[15-17]等，其中，荷载传递法因可通过不同的桩土相互作用模型来反映桩土共同作用、地基层状特性而被学者广泛运用。总的来说，基于荷载传递法的桩土相互作用模型主要有理想弹塑性模型[1，4-6]、双折线硬化模型[3，18]、三折线模型[19]及双曲线模型[7]，通过选取不同的桩土相互作用模型，可以较准确地得到不同土性中单桩的沉降，具有较好的工程适用性。……