Overburden management in open pits: options and limits in large limestone quarries

The management of overburden is an important task in open pit exploitations. Site topography and morphology as well as geological and geotechnical properties of natural and remoulded materials are the most important factors affecting the disposal phase. Economic and environmental requirements must be followed in order to achieve the best reclamation results, keeping into account site constraints such as slope stability, hauling and dumping issues, and interactions with groundwater. This paper deals with the above mentioned issues, illustrating a rational approach applied on the case of a large limestone quarry where the thickness of the overburden is relevant and the spoil material has to be dumped in a flooded pit. The proposed multidisciplinary approach led to the selection of most suitable methods for excavation, transportation and disposal. The selection was based on a detailed laboratory and site characterisation that defined favorable and adverse factors to be considered during the preliminary study of a large quarrying project.

Optimal design for buckets layout based on muck removal analysis of TBM cutterhead

The layout of the buckets for tunnel boring machine(TBM)directly affects the muck removal efficiency of cutterhead during excavation.In order to improve the muck removal performance for TBM,the optimal design of bucket layout was investigated.The whole muck transfer process was simulated by discrete-element method(DEM),including the muck falling,colliding,pilling up,shoveling and transferring into the hopper.The muck model was established based on size distribution analysis of muck samples from the water-supply tunnel project in Jilin Province,China.Then,the influence of the bucket number and the interval angle between buckets on muck removal performance was investigated.The results indicated that,as the number of buckets increased from four to eight,the removed muck increased by 29%and the residual volume decreased by 40.5%,and the process became steadier.Different interval angles between buckets were corresponding to different removed muck irregularly,but the residual muck number increased generally with the angles.The optimal layout of buckets for the cutterhead in this tunnel project was obtained based on the simulation results,and the muck removal performance of the TBM was verified by the actual data in the engineering construction.

有“腿”更任性 Menzi Muck M系列步履式挖掘机

有人喜欢履带式挖掘机,因为它稳定;也有人喜欢轮式挖掘机,因为它灵活。当一台步履式挖掘机出现在自己面前时,所有人都不淡定了。步履式挖掘机如今对国内工程机械用户来说已不算什么新鲜事物,国内也有企业推出过步履式挖掘机产品,如徐工在bauma China 2010上就推出了ET110型步履式挖掘机。尽管如此,Menzi Muck旗下的M系列步履式挖掘机在bauma China 2014上还是吸引了很多人的关注。兼得鱼和熊掌步履式挖掘机工作形式与传统履带式挖掘机和轮式挖掘机大致相同。