Design And Robust Optimization Of Urban Construction&Demolition Waste Recycling Network

The solid waste generated during construction and demolition projects is not only huge,but with inappropriate disposal measures,such as open-air storage and simple landfill,can also causes irreversible pollution to environment.With acceleration of Chinese urbanization process,the output of construction waste will continue to grow,and it is particularly important to establish a scientific and complete recycling system.In the construction waste recycling industry,the goals pursued by policy makers and interest groups are different and even conflict with each other.Therefore,the recycling network system needs to balance the standardized disposal of construction waste and improve recycling industry operating benefits goals.In addition,affected by factors such as national policies and regional economic activities,the construction waste recycling system is under an uncertain operating environment,which makes the construction of recycling network more difficult.Based on the background described above,this article carried out the following research.First of all,using methods such as consulting news reports and government policies,consulting with practitioners and field research,based on in-depth understanding of the current status of the domestic construction waste recycling industry,this article divided it into four subsystems:construction waste generation,sorting,processing and demand,which provides a basis for the model structure design and parameter value determination.Then this article designs a recycling network that includes construction waste generation points,recycling points,landfills,and demand points.The optimization goals are to minimize the cost of construction enterprises,maximize the profits of recycling companies,and maximize the waste recovery rate,and build a multi-cycle multi-objective mixed integer linear programming model.Then,an empirical study was conducted in Beijing.By comparing the similarities and differences of the results when three goals separately optimized,the contradictions and connections between the goals are analyzed.Using constraint theory,a single-objective model was obtained.The overall economic benefits and the facility utilization are used as the goal,and the recycling rate is classified as model constraint.The solving process is completed by CPLEX software,and the new expansion of the treatment construction plan is obtained.Finally,considering the uncertain characteristics of the construction waste recycling network,the model is robustly optimized.The robustness evaluation index is constructed to analyze the influence of six random parameter on the model,and it was found that the amount of construction waste is the main factor reducing the model.robustness.This article proposes a two-stage robust optimization method:in the first stage,uncertain programming theory is used to obtain a chance-constrained model,which solves the problem of construction waste amount fluctuations,at the same time alternative plans are determined;in the second stage,considering overall economic benefit,recycling rate and facility utilization,a decision matrix is constructed and the TOPSIS method is used to rank the alternative plans.The results show the validity of the proposed model.