考虑附加抗力影响的单桩水平受力分析方法

单桩基础受水平荷载作用时，桩身截面转动引起的竖向摩阻力形成土对桩的附加抗力矩，同时桩端土对桩也有一定的附加抗力效应。为了研究桩身和桩端附加抗力对单桩水平承载特性的影响，该文基于API规范推荐的砂土摩阻力模型，结合桩身径向土压力引起的极限摩阻力增强效应，推导出砂土中桩身抗力矩的离散数值解和简化公式解；采用API规范推荐的黏性土摩阻力模型，推导出黏性土中桩身抗力矩的离散数值解和简化公式解。基于双曲线桩端竖向应力-位移模型，在考虑桩端桩-土界面脱开效应的基础上，得到了桩端抗力矩的离散数值解和简化公式解，桩端水平剪力的离散数值解；进而提出基于Winkler地基梁模型的有限元计算方法，并编制了程序。通过对比试验数据，初步验证了该文方法的正确性，进行了水平承载力的参数分析，结果表明:随着长径比的增加，附加抗力在总水平承载力中的占比逐渐减小；而随着桩直径的增加，附加抗力在总水平承载力中的占比并未显著变化。

A METHOD OF ANALYZING LATERALLY LOADED MONOPILES CONSIDERING THE INFLUENCE OF ADDITIONAL RESISTANCE

When a single-pile foundation is subjected to horizontal loads, the vertical friction resulting from the cross-sectional rotation of the pile develops into an additional resistance moment from the soil to the pile, and the soil at the pile tip also forms a certain additional resistance on the pile. To explore the influence of the additional resistance of the pile and pile tip on the horizontal bearing features of the single pile, deduces the discrete numerical solution and simplified formula solution of additional moment based on the friction model of sand recommended by the API code in combination with the ultimate friction enhancement effect caused by the radial soil pressure. Also adopts the friction model of clay recommended by the API code to deduce the discrete numerical solution and simplified formula solution of the additional moment in the cohesive soil. Based on the hyperbolic stress-displacement model and the separation effect of pile-soil interface, deduces the discrete numerical solution and simplified formula solution for the pile tip additional moment and the discrete numerical solution of pile tip horizontal shear force. Furthermore, proposes a finite element method based on the Winkler foundation beam model and compiles a program. By comparing with the experimental data, the correctness of the method adopted in this paper is verified. The parameters of the horizontal bearing capacity are analyzed. The results show that, as the ratio of pile length to diameter increases, the proportion of additional resistance in the total horizontal bearing capacity gradually decreases, while the proportion of additional resistance in the total horizontal bearing capacity shows no significant changes as the pile diameter increases.