为得到满足可靠性要求的基桩最佳设计方案，在有效控制基桩沉降量的情况下，尽可能降低基桩造价。以中国尊大厦基桩为例，考虑土体极限阻力不确定性，采用非支配排序遗传算法-II（NSGA-II），针对种群中的个体进行非支配解选择排序和拥挤距离比较。将桩径和桩长视为优化设计变量，以基桩承载力的目标可靠指标作为约束条件，工程造价和单桩沉降量的最小值为目标函数，得到Pareto最优解集。该算法解决了传统多目标优化方法在缺乏经验的情况下优化效果不佳与速度慢的问题。采用基于熵权理论的TOPSIS法对Pareto最优解集中的每一个解进行赋权后，筛选出相对贴近度最大的方案。结果表明：最优方案在造价和单桩沉降量上均优于原设计方案，证明基桩优化设计方法具有可行性。

In order to obtain the optimal design scheme of a foundation pile that meets the reliability requirements, the construction cost of foundation piles should be reduced as much as possible under the condition of effectively controlling the settlement of foundation piles. In this paper, the foundation pile of the China Zun Mansion is taken as an example, and the inherent uncertainty in the ultimate resistance of soils is considered. The non-dominated sorting genetic algorithm-II (NSGA-II) is used, which includes the non-dominated solution selection sorting and crowing distance comparison for individuals in a population. In this algorithm, the pile diameter and pile length are regarded as optimal design variables, the targeted reliability index of the bearing capacity for foundation pile is taken as constraint condition, and the minimum engineering cost and the lowest settlement is taken as an objective function. The Pareto optimal solution set is obtained, and a few shortcomings are resolved, such as the poor optimization performance and slow speed of traditional multi-objective optimization methods in the absence of experience. Moreover, each solution in the Pareto optimal solution set is weighted by using the TOPSIS method based on the entropy weight theory, the best scheme is chosen with the largest relative closeness. The results show that the chosen scheme is slightly better than the original design scheme in terms of construction cost and pile settlement, which demonstrates that the proposed optimal design method for foundation piles is feasible.

TU473.1

河北省自然科学基金（E2019201296）；河北省建筑业科技计划（KJJH2022004）；河北大学研究生创新资助项目（HBU2022ss019）