Research On Capacity Calculation And Optimization Of Receiving-Unloading System In Heavy Haul Railway Unloading Station

With the characteristics of large capacity, high efficiency and low transportation cost, heavy haul railway is one of the main directions of railway freight development. Heavy haul railway unloading station is the last part of coal transportation on railway, and it is also the first part of coal entering port. As a key point of connecting railway and port, the capacity of receiving-unloading system in unloading station would restrict the whole transport capacity of passage. It has significance to analyze capacity of receiving-unloading system and optimize the unloading process for enhancing heavy haul railway capacity, optimizing transport organization and reducing equipment waste.Based on the domestic and international research of unloading capacity, the article introduces equipment, operation process and station yard layout, and put forward concept of receiving-unloading system. Combining with queuing theory, it analyzes constitution of receiving-unloading system and influence on system capacity with service time imbalance and operation fluctuation. It also models the queuing system to calculate queuing index and capacity of each subsystem.In order to show the interaction completely among three subsystems, the paper presents that receiving-unloading system could be abstracted to a closed queuing network models, and works out the computing method of closed network capacity and queuing index with steady state. The condition of using closed queuing network models is steady flow in system, but whether flow is steady depends on input flow stability, allocated quantity of each point and coordination of operations in the whole system. It could realize stability of input flow by controlling headways of trains in railway section.On the basis of researching cumulative counts of arrival trains and departure trains in system and cumulative train counts processed in station operations, the article analyzes queue balance with steady flow and builds queuing balance model of receiving-unloading system. The model calculates optimal allocated quantity with the goal of balanced queue length of each point and constraint conditions of maximum system capacity.After obtaining steady input flow and optimal allocated quantity, it needs to optimize each operation to reduce interference and improve coordination aiming at maximize system capacity. Based on analyzing contents and factors of unloading lines utilization scheme, the paper builds optimization model and algorithm using time slice which is the simplified description of time intersects. Eventually, taking Huanghuagang station on Shuohuang railway for example, the article introduces unloading equipment, operation process, time standard and yard layout. Based on this, it calculates system capacity and optimal quantity allocated with different proportions of gondola car and hopper wagon. It also optimizes the unloading lines utilization in Huanghuagang station and obtains optimal scheme with minimum interference.