Study On Safety Of Conversion From Well To Open Pit In Ciyaota Coal Mine

With the increasing demand for coal resources in China,in order to improve the recovery and utilization rate of coal resources,most mines in China have adopted the mining method of converting well mining to open pit mining to recover a large amount of remaining coal.However,due to the exploitation of the original well and mine site,resulting in a large number of mined-out areas of different forms and unknown locations,this has brought a great security hazard to open-pit mining.How to determine the specific location of goaf and its distribution influence area has become an urgent problem to be solved in the process of well-working to open-pit mining.In view of the difficult problem of how to determine the position and scope of the goaf in the process of converting the well worker to the open pit mining,this paper takes the project background of the conversion of the miner to the open pit mining in the porcelain kiln tower coal mine.The location and range of goaf are accurately detected by using transient electromagnetic cross-section detection technology.On this basis,the same load is applied to the upper strata of the goaf with definite scope(that is,large-scale mining machinery equipment such as mine trucks),and the same load is applied to the upper strata of the well-defined goaf by means of transient electromagnetic section detection technology.The safe bearing thickness of the upper strata in the study area is determined by the method of theoretical analysis.The research contents are divided into the following aspects:(1)The atem transient electromagnetic transmitter and atem transient electromagnetic receiver are used in the open pit stope area to correct the transient electromagnetic detection parameters with different emission current,different frame area and different iteration times,and the reasonable parameters are selected.It makes it more accurate to detect goaf.(2)Based on the analysis of the detection results,the shape,scale,variation characteristics and numerical value of the apparent resistance isoline are obtained,and the schematic diagram of the position and range of the underground goaf is drawn.(3)Through theoretical calculation,the stability of coal pillar and the safe bearing thickness of overlying rock are analyzed theoretically.(4)According to the schematic diagram of goaf position,the goaf model is established by using FLAC3 D software.The stability of overlying rock is simulated by applying equal load above goaf,and finally the safe bearing thickness of overlying rock is obtained when mining above goaf.In this paper,the space position,shape and scope of goaf are determined by using transient electromagnetic method,and the same load is applied to the upper strata of goaf(that is,heavy truck and other large mining machinery and equipment),and the bearing capacity of overburden rock is analyzed.The safety bearing thickness of overburden rock is obtained,which provides a certain reference value and guiding significance for porcelain kiln tower coal mine and other miners with similar geological conditions to open-pit mining.