桩径优化是桩筏基础以差异沉降最小化为目标的基础优化分析的重要组成部分。基于桩筏基础通用分析方法，结合遗传算法提出了包含非线性约束条件的以差异沉降控制为目标的桩筏基础桩径优化分析模型，并给出了优化分析的实施步骤。通过示例说明了桩径优化的实施情况，对比给出了优化前后基础沉降、桩基荷载分布与筏板分担比、筏板弯矩和剪力结果。最后通过参量分析研究了筏板厚度、桩基参量和土体参量对最优桩径确定的影响程度，桩长和土体特性对桩径优化结果影响显著，而桩体材料特性和筏板厚度对桩径优化结果影响不大。

Pile diameter optimization is an important part of piled raft foundation analysis for the purpose of minimizing the differential settlement. Based on a general analysis method of piled raft foundation, this paper proposed a pile diameter optimization model with the genetic algorithm. The optimization model contains an objective function of differential settlement and other nonlinear constraints. Detailed process steps are listed. Implementation of pile diameter optimization is illustrated by an example, with a contrast before and after the optimization of foundation settlement, pile load distribution, raft bearing ratio, shear and bending moment of the raft. The influences of raft thickness, piled foundation parameters and soil parameters on the optimal diameter are also studied by parameter analysis. Results show that piled length and soil property have a significant impact on radius optimization than pile body material properties and raft depth.