| There are many problems in Ningdong coal power base,such as large stock of coalbased solid wastes,low comprehensive utilization rate and environmental pollution,which seriously restrict the construction of regional ecological civilization and high-quality economic and social development.Taking the 110903 fully mechanized face of Renjiazhuang coal mine as the research background,this paper reveals the formation mechanism of overburden separation,distinguishes the spatial position of overburden separation,analyzes the dynamic evolution characteristics of overburden fractures in multi coal seams mining,and explores the feasibility of filling the lower separation zone and caving zone in the gob by using the methods of theoretical calculation,numerical simulation and similar simulation.The following research results have been achieved:(1)Based on the key strata theory and the comprehensive columnar shape of 110903 fully mechanized face,it is determined that the number of key stratas of overburden is 4.The coal seams in Renjiazhuang coal mine are coal 3,coal 5 and coal 9 from top to bottom.Key strata 1 and key strata 2 are located between coal 9 and coal 5,and key strata 3 and key strata 4 are located above coal 3.(2)The discrete element numerical model for the evolution of overburden fractures in multi coal seam mining is constructed,and the dynamic evolution of overburden separation in multi coal seam downward mining shows a periodic change law of development expansion continuation closure redevelopment.It is found that the separation space lags behind the formation of the working face,and the key layer is conducive to the development and expansion of bed separation.(3)Affected by the repeated mining of coal 3 and coal 5,the key layer 3 and key layer4 above coal 5 are difficult to form a structure.When mining coal 9,the key layer 2 above coal 9 bears all the loads of the overlying strata,and the subsidence is severe,so it is difficult to carry out separation grouting filling.Before the gangue in the gob is compacted,there is a large amount of separation space,which can be filled by grouting in the caving area.(4)A similar simulation model of caving mining and filling mining in the caving area is established.Through grouting and filling in the separation space of the caving area,the key strata 2 is only bent but not broken compared with the caving mining,the advance bearing pressure is reduced,and the subsidence coefficient of the key strata 2 is reduced by53%,indicating that the grouting and filling in the caving area can effectively control the subsidence of the overburden.(5)Based on the engineering geological conditions of 110903 fully mechanized face and the above research results,the grouting filling scheme in the caving area is designed,and the key parameters of grouting filling in the caving area are determined.The field industrial test was carried out.The total amount of solid waste for tunnel pipe laying and filling was 8t(1t gangue,4t fly ash,1.5t gasified slag and 1.5t furnace bottom slag),the total amount of solid waste for pipe hanging and filling was 5t(3t fly ash,1t gasified slag and 1t furnace bottom slag),and the water consumption for grouting was 2.1t.The slurry is stably transported in the pipeline,and the space behind the support is gradually filled with slurry.The test shows that the grouting filling in the caving area is feasible.Figure [53] Table [13] Reference [87]... |
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