Research On Logistics Optimization Of Urban Construction Projects With Low Carbon Constraints

According to the “Regulations for the Management of Construction Projects”,urban construction projects include all civil construction projects that occur in urban areas,such as commercial real estate development,urban subway construction,road construction,and old city demolition and reconstruction.Construction project logistics provide resource allocation services for construction projects.This process consumes energy and produces a large amount of carbon emissions,which has a serious negative impact on the urban environment.In the context of carbon emission constraints,targeting engineering construction projects in the process of urbanization in China and optimizing the related logistics activities is not only a requirement of China’s macroenvironmental policy for enterprises but also an inevitable choice for related enterprises to save costs and operate in an orderly manner.According to the characteristics of urban construction logistics,this paper proposes joint logistics operations among construction project contractors.Based on the economic order quantity(EOQ)model,the vehicle routing problem(VRP)model and the location-routing problem(LRP)model,a series of mathematical models are constructed to optimize several key problems of urban construction project logistics under low carbon constraints.The main research work of this thesis is as follows.(1)The composition and carbon emissions of the logistics chain of urban construction projects are explained,and the value of the logistics chain is analyzed.Based on the shortcomings of the existing logistics mode of urban construction projects in energy saving,emission reduction and logistics efficiency,a logistics cooperation mode among construction project contractors is proposed.Through the CCLCC(city construction logistics consolidation center),contractors integrate urban construction logistics activities and resources,reduce energy consumption and carbon emissions,and improve logistics efficiency by centralized procurement,centralized processing,the joint distribution of engineering materials,and the priority allocation of earthworks among engineering contractors.(2)Based on the logistics cooperation mode between contractors and two carbon constraints policies,the optimal decision models of the centralized procurement of engineering materials,namely,EEOQ and E(s,S),are constructed under deterministic and stochastic demand conditions,respectively.The effects of the carbon tax rate,carbon price,carbon quota and carbon emission factor on procurement decisionmaking,total cost and total emissions are analyzed,and numerical validation is carried out.In the optimization of procurement inventory,this paper overcomes the limitation of a single enterprise,realizes the optimization of multi-contractors in the procurement storage link by means of joint logistics operation,and pursues the saving of logistics costs and the reduction of carbon emissions.Different combinations of carbon trading prices and carbon emission quotas are used to construct strict,moderate and weak carbon restriction policies.It is found that the three carbon constraint policies(strict,moderate and weak)correspond to obvious,moderate,and possibly ineffective emission reduction effects,respectively.(3)Based on the carbon tax policy and the logistics cooperation mode among contractors,this paper proposes an ETDVRPTW model for the vehicle routing optimization of the urban co-distribution of construction materials under low carbon constraints.It incorporates factors such as the time-varying speeds of road condition dependence,the service time windows of the contractor’s site and carbon emission policy constraints.Empirical and virtual data are used to verify the results.The calculations of vehicle carbon emissions and fuel consumption more truly reflect the impact of urban road conditions.The improved genetic algorithm is used to solve the model,which shortens the coding length of the population and makes the solution faster.(4)Based on the logistics cooperation mode among contractors,carbon emission constraints are introduced into the optimization of urban earthworks recovery logistics.An optimization model ELRP is constructed to solve the multi-attribute decision-making problem.The model considers multiple influencing factors,such as energy savings and emission reductions,economic costs,time efficiency,market competition and so on.In the optimization process,the combination of the link and an alternative point is taken as an alternative scheme to meet the goal of location and path integration optimization.An improved linear proportional transformation(LPT)method is proposed for data standardization.The transient vehicle speed is used to calculate the fuel consumption,carbon emissions and travel time of the link.The TOPSIS method based on subjective and objective combination weights is used to rank and optimize the alternatives.The empirical results show that the low carbonconstrained optimization scheme of earthworks recycling logistics has advantages in energy savings,emission reductions,costs and operation time savings.In this paper,the idea of a sharing economy is introduced into the logistics optimization of urban construction projects,and a logistics cooperation mode among contractors is proposed.On this basis,the centralized procurement,the co-distribution of engineering materials and the recycling logistics of engineering earthworks are optimized.The current research explores the application of modern logistics management ideas and theories in urban construction projects and expands the applicability and application scope of the classic EOQ model,VRP model and LRP model.