The Construction And Operation Optimization Of Underground Container Logistics System Based On Port Collection And Distribution

In recent years,Chinese ports have developed rail-water intermodal transport and waterwater transfer to cope with the pressure of container transport brought by the growth of international trade.It further promotes the development of port container collection and distribution.The traditional port container collection and distribution mainly realizes the cargo flow between the port and the inland area by road transportation and railway transportation.However,the transportation mode of port collection and distribution is relatively monotonous,and most of the ports in China do not have direct railway connection.The port dredging process mainly relies on highway transportation,thus squeezing urban road resources.This leads to serious road congestion,increased traffic accident rate and serious environmental pollution.Underground Logistics System(ULS)has the characteristics of low pollution,high efficiency and strong safety,especially the Underground Container Logistics System(UCLS)connected with ports and railways.This system can alleviate the contradiction between port and city and improve the logistics efficiency of port and city.As a new transportation system that meets the requirements of sustainable development,it will play an important role in transportation in the future.But now lack of underground logistics system combined with container distribution system layout design,more lack of relevant theoretical research foundation.In view of the above situation,this paper takes the UCLS as the research object,and constructs the UCLS in view of the shortcomings of the existing port collection and distribution system.The layout and operation flow of UCLS are designed.A two-stage model under government carbon subsidy is established to research the transportation planning of underground logistics.The container storage space sharing problem considering ULS,as well as the volume allocation and equipment scheduling problem of different deep and shallow underground channels are studied.The main work includes:(1)Construction of UCLS based on port collection and distribution.Urban underground logistics system for multi-layer framework:deep UCLS from seaport to suburban logistics park,shallow UCLS from seaport to railway station.Combined with the characteristics of container multimodal transport,the UCLS based on port multimodal transport is studied and designed.There are mainly deep underground channel design and shallow underground channel design.Deep channel is mainly based on vertical handling mode.The use of shuttle vehicles in the deep channel not only improves transportation and efficiency,but also makes more effective use of space resources.The shallow channel mainly uses the ramp underground entrance and exit,uses the Automated Guided Vehicle(AGV)to innovate the transportation mode of container sea-rail intermodal transportation,and explores the AGV marshalling transportation in the shallow channel.In addition,the layout,business process and process design of the two underground channels are discussed,and the system analysis is carried out in three ways.(2)Transportation planning of ULS considering government carbon emission subsidy.This paper mainly studies the organization planning of underground logistics transportation considering container volume distribution under low carbon policy.The economic mode considering carbon tax and carbon subsidies is proposed to help the government and port enterprises jointly promote the use of UCLS.First,the government and ports are linked based on low-carbon policies.Considering the allocation of container traffic,the use of carbon tax and carbon subsidies to promote the use of underground logistics in port transportation,thereby promoting the emission reduction effect of the collection and distribution system.Secondly,a two-stage robust model for underground channel selection and container volume allocation is established.Solve the transportation mode selection and volume allocation decision under uncertain transportation demand.In this paper,the Column and Constraint Generation(C&CG)algorithm is used to solve the two-stage robust optimization model,and the container traffic assignment scheme under demand uncertainty is obtained.According to the calculation results,the paper analyzes three factors,including:the influence of low carbon policy on the underground logistics transportation organization planning under the determined demand,the influence of uncertain parameters on the underground logistics transportation organization planning,and the volume distribution after the underground logistics transportation organization planning.The results show that:1)When the tax rate is 15 CNY/kg and the subsidy rate is 20 CNY/kg,the total cost of the system is the lowest,which is 1146.71 million CNY.2)In the case of demand fluctuations,the system tends to be stable when the uncertainty level is 0.6.That is,in this case,the transportation lines selected by the system are more reasonable,including 6 highway transportation lines,2 deep underground transportation lines and 1 shallow underground transportation line.(3)Container storage space sharing considering underground logistics.The yard sharing strategy refers to sharing the remaining storage space of the land port to the container terminal to alleviate the problem of insufficient storage space of the container terminal.Firstly,this paper establishes a multi-objective mixed integer programming model for yard sharing with the objective of minimizing the total transport distance,minimizing the imbalance of container quantity and maximizing the shared storage space between land and port,and uses the NSGA-II method to solve the model.Next,through a set of examples to verify the performance of the algorithm,intuitively illustrates the advantages of the yard sharing strategy.In addition,the model shows the advantages of yard sharing strategy from four aspects of performance and proves its comprehensiveness.Finally,through the sensitivity analysis of the transport distance,the validity of the model is verified.The results show that:1)Compared with the random storage strategy,the average storage space of land port sharing is increased by 14.63%,and the total cost of container transportation and storage imbalance is reduced by 21.28%.2)Compared with the traditional strategy,yard sharing strategy balances the overall container volume of container terminals and land ports.3)With the increase of the distance between the two terminals,the number of containers allocated to land ports gradually decreases,while the number of containers allocated to container terminals gradually increases.4)Considering the operation balance of container area is beneficial to reduce the imbalance of container number.(4)Joint scheduling of equipment connection in UCLS.This paper mainly studies the equipment joint scheduling problem in deep underground channel of UCLS.Firstly,the layout and operation process of UCLS in automated container terminals are introduced.Secondly,the scheduling optimization problem of gantry crane above the shaft of UCLS under the strategy of loading while unloading is studied.The mathematical model of gantry crane with the minimum maximum completion time as the objective function is established,and the constraints are taken into account when the container is operated by gantry crane,AGV and Underground Logistics Vehicle(ULV)at the shaft.The proposed model is solved by IAGA on a small-scale example,and the influence of equipment scheduling scheme,the comparison of ULV marshalling and non-marshalling modes,and the different departure intervals of ULV are obtained.The results show that:1)Under the strategy of loading while unloading,the operation efficiency of shaft equipment is higher,and the total completion time of hanger is 29 mins.2)Compared with the ULV single mode,the ULV marshalling mode has certain advantages,but it will increase the waiting time of ULV and AGV.3)The departure interval of ULV will affect the ULV single mode,especially after the departure interval is 3 mins.4)After introducing the multi-objective comparison,the completion time of the hanger and the waiting time of the ULV are weighed to make the experimental results more scientific.From the perspective of operational research,economics and engineering design,this paper mainly studies the early transportation organization planning,medium-term layout design and later operation optimization of UCLS based on port collection and distribution.At the same time,taking into account the influence of uncertainty,low carbon transportation,yard sharing,strategy of loading while unloading on the whole system,the relevant theories of UCLS are explored and enriched.It shows that the UCLS has certain application feasibility in implementing energy saving and emission reduction,alleviating the contradiction between port and city,and promoting the transformation of traditional freight technology.It has certain reference significance for theoretical research and practical operation of UCLS based on port multimodal transportation.