Abstract: There are two ore unloading lines in -420 m level of Meishan Iron Mine undertakes the transport work of iron ore,due to the heavy rolling of heavy vehicles for many years,the serious subsidence problem of the monolithic roadbed of the two ore unloading lines in -420 m level of the mine is existed,which directly leads to excessive resistance when the tipper pulls ores into ore unloading lines,the collision phenomens of the head of 25 t electric locomotive and horizontal supporting wheel and vertical supporting wheel in the entrance of ore unloading lines are appeared,and the problem of unsmooth ore unloading is existed when the heavy trucks into ore unloading lines.In serious cases,the heavy trucks may be drop at the entrance of ore unloading lines,besides that,the head of electric locomotive and hevay trucks may be stuck on ore unloading lines.Therefore,the safety application of ore unloading lines is affected and the production efficiency of iron ores of Meishan Iorn Mine is also affected.Through the optimization of blasting excavation method for the monolithic roadbed in the entrance of two ore unloading lines in -420 m level,a new monolithic roadbed construction technique is proposed and applied,the whole strength of the entrance zone of the monolithic roadbed of ore unloading lines is enhanced,the abvoe problems are solved effectively,the safety application of ore unloading lines is ensured,besides that,production efficiency of iron ores of the mine is improved.

Key words: Iron ore, Ore transport, Ore unloading line, Monolithic roadbed construction technique, Lossening blasting, Ore production efficiency