基于Pareto解的面板堆石坝施工工期-质量-成本均衡优化研究

摘要

Whether the three core elements,time-quality-cost,can reach tradeoff optimization or not in dam project is an important metric of project evaluation.Aiming at the fact that the problem of lack of time-quality-cost tradeoff optimization research in dam construction field and the fact that multi-objective tradeoff optimization had not just one optimal solution but a group of Pareto solutions,this paper established the time-quality-cost tradeoff optimization mathematical model for rockfill dam construction,and Pareto superposition model was built to solve the dominance relation between combination solutions.The conclusion showed that the combination solution which was composed of Pareto solutions of process was still Pareto solution.The feasibility of coupling linear weighted sum(LWS)method was verified by comparative analysis of LWS method and technical for order preference by similarity to ideal solu-tion(TOPSIS)method,and the modifiednon-dominated sorting genetic algorithms(NSGA-Ⅱ)coupling LWS was proposed based on the conclusion of Pareto superposition model and integrated with multi-attribute utility function, which reduced the computational complexity,improved the computational efficiency and robustness of the algorithm,and overcame the problem that there was more than one optimal solution.Simultaneously,on the practi-cal basis of a rockfill dam project,the computational efficiency was improved by applying the modified algorithm, and the best compromise solution was chosen in accordance with engineering practice.%大坝工程中能否对工期、质量、成本3大核心要素进行综合均衡优化,是评价工程项目的重要衡量标准.针对目前大坝工程施工缺少工期-质量-成本均衡优化研究,且多目标均衡优化最优解非唯一、存在一组Pareto解集的问题,建立了面板堆石坝施工工期-质量-成本均衡优化数学模型,并建立了Pareto叠加模型对组合解支配关系进行求解.结果表明:基于工序Pareto解的组合解大部分仍为Pareto解;通过对线性加权和法与TOPSIS法的比较分析,验证了耦合线性加权和法的可行性.基于Pareto叠加模型结论并结合多属性效用函数提出了改进的耦合线性加权和的带精英策略非支配排序遗传算法(NSGA-Ⅱ),降低了算法的计算复杂度且提高了计算效率和鲁棒性,克服了最优解非唯一的问题.同时,结合某面板堆石坝工程,运用改进算法提高了计算效率,并优选了符合工程实际的最优折衷方案.