Study On Optimization Of Transportation System And Truck Scheduling In The Open-pit

An open-pit typically has the larger output,higher recovery rate and overall labor efficiency than the underground mine.Since the electic shovel and truck are both specialized equipments with very large scale in the “shovel-truck” discontinuous production system,the open-pit always requires great equipment investment and goes by the high fuel oil consumption.How to save energy and reduce consumption at the same time of ensuring the high equipment utilization and production capacity has become an urgent problem in the open tripping.The problem is generally addressed in three levels: development plan of the open-pit,the production equipment,and production and logistics management.Taking into consideration the transportition system and truck logistics respectively,the research tries to improve the production and logistics process in the open-pit.It can help to reduce the average transportaiton distance and increase the equipment operation efficiency and thus to save energy and reduce consumption.An intermediate bridge is a road that is poiled up by the stripped rock.Compared with the end slope transportation,the intermediate bridge transportation can reduce the truck transportation distance and the total mining cost can be saved under some conditions.The truck transportaion is the main section of the fuel oil consumption in the shovel-truck system.And the proper truck dispach,loading and unloading point match and truck rounting can decrease the truck waiting time and reduce transportion distance and thus save energy consumption while ensuring the production capacity.Centrating on the central bridge transportation system and truck scheduling decision,the main contents of the thesis are as follows.1)The applicability of the intermediate bridge transportation system is analyzed for the open-pit with complex geological conditions.The traditional intermediate bridge transportation is just suitable for the flat seam.The thesis anlyses the applicability for the complex geological conditions such as anticline and fault.Based on the formulated inequality that the dumping cost through the intermediate bridge is not more than that through the end slope transportation,the optimization decision model of its reasonable service level.Taking some a surface mine with anticline and fault as an practical instance,the construction level,service level and economic benefits of the intermediate bridge are demonstrated.2)The truck scheduling problem is studied which takes the production planning and scheduling practice in the open-pit as the research background.Based on the truck and road network conditions in the open-pit,a mixed integer programming model is formulated for the truck scheduling problem with objective of the total transportation revenue,taking into consideration the mining sequence.A few valid inequalities,properties and upper bounds are proposed through analyzing features of the problem and its model.Based on the inequalities,properties and upper bounds,a heuristic solution approach and two improvement strategies are proposed to resolve the problem.The numerical experiment demonstrates that the proposed solution approach is effective and efficient with computing times no larger than 5 minustes and the average gap 4.46%.3)Another special truck scheduling problem considering the mixing ratios of different coal quality in the coal open-pit is addressed.For the new features of the truck scheduling,an integer programming model is formulated to describe the problem.And a few valid inequalities are deduced,some properties and two upper bounds of the problem are proposed and a relaxed integer programming model is introduced.Based on the resoluble relaxed model,a mixed fixed/supplementive truck allocation-based optimization approach is proposed for the problem.The approach is also adapted to tow particular truck operation condition and scheudling requirements,through introducing some new constraint inquentions.At last,computation experiments are executed on a series of practical instances,which show that the proposed approach can obtain a nearoptimum solution with the average gap 4.32% in the acceptable CPU time.