堆载作用下被动桩的水平受力及位移分析

针对既有桩体在较大侧向堆载作用下会发生偏斜或挠曲变形甚至开裂折断，从而导致结构存在较大安全风险的问题，基于Flamant解建立条形荷载作用下的水平附加应力计算公式。考虑到桩-土界面的剪切效应，采用双参数地基模型进行桩后土体的桩-土受力分析。建立了被动桩的挠曲微分方程，采用MATLAB求解得到桩的内力及变形情况。采用文献中的不平衡堆载试验监测数据验证了计算公式的合理性。研究结果表明:堆载对桩基的侧向土压力影响主要分布在桩体的上半部分，受到的侧向土压力占桩体总侧向土压力的86%以上；随着堆载高度的增加，桩的侧向土压力、侧向位移和弯矩均呈现出增大的趋势；所得结论可为类似工程的安全性评价提供理论依据。

Analysis of Lateral Force and Displacement for Passive Piles Under Surcharge Load

According to the problem of pile deviation or flexural deformation, even cracking and breaking under large lateral surcharge load, which caused large structural safety risk for pile structure. Based on the Flamant solution, the formula of lateral additional stress under the strip load was obtained. Considering the shear effect of interface between the pile and the soil, the two-arameter foundation model was applied to analyze pile-soil force of soil behind the passive pile. The flexural differential equation of passive pile was established, and the internal force and deformation of piles were obtained by MATLAB. The reasonableness of the formula was verified by the unbalance load test data in the literature. The study results show that the effect of surcharge load on lateral earth pressure on the pile is mainly distributed in the upper part of pile, the lateral earth pressure is accounted 86% of the total pile lateral soil pressure. With the increase of loading height, lateral earth pressure, lateral displacement and bending moment of pile show an increasing trend. The conclusions can provide a theoretical basis for the safety evaluation of similar projects.