Research And Application Of End Partial Filling Technology In Fully Mechanized Caving Mining

With the continuous development of the economy,thick coal seams have become the main production coal seam of China's coal enterprises,and the output can reach about 45%of the total output.Therefore,how to achieve safe and efficient mining of thick coal seams under special geological conditions such as "three downs" has been It is a key concern of relevant scholars and mining workers.Although filling mining has been proved to be an effective way to liberate"three downs" coal,most of the thick coal seams currently use integrated mechanized top coal mining technology,and its combination with filling and mining has not yet formed a complete theoretical system.Therefore,this paper takes the Qinggangping coal mine in Xunyi,Shaanxi Province as the engineering background,and puts forward the technical method of end partial filling technology in fully mechanized caving mining,which provides a new idea for the combination of top coal mining and filling mining.In this paper,theoretical analysis,mechanical model analysis and other methods are used to analyze the key factors affecting the filling effect of the method.The FLAC3D numerical simulation software is used to analyze the migration law of the overlying strata after filling,and the industrial test is carried out in Qinggangping Coal Mine.The filling effect of the method was evaluated by field observation data.The main research results are as follows:(1)A end partial filling technology in fully mechanized caving mining is proposed,and the determination method of the width of the end filling body is given.The specific supporting form of the end filling space is determined.The mechanical model of the roof slab beam is established,and the three main factors affecting the filling effect are calculated by the calculation:the filling rate,the width of the tip filling body,and the strength of the filling body.(2)Using FLAC3D numerical simulation software,the migration law of overburden on the working face under different filling rate,tip filling width and filling body strength is analyzed.With the increase of the enrichment rate,the stress,displacement and plastic failure zone of the overburden are gradually reduced,but the decreasing trend is not significant.When the filling rate reaches 100%,a mutation occurs,which effectively reduces the height of the overburden stress arch.As the width of the tip filling body increases,the height of the overburden stress arch decreases continuously.When the width of the filling body increases from 10m to 20m,the overburden stress arch decreases the most,about 14m,and the stress arch The shell curve undergoes structural changes and some areas are no longer smooth.When the strength of the filling body is less than 0.4 GPa,the strength does not meet the minimum strength required for local filling of the tip.When the strength of the filling body is greater than 0.4 GPa,the load carrying capacity of the filling body increases with the increase of strength.The stress,displacement,plastic failure zone of the overlying strata and the stress concentration peaks at both sides of the coal wall show a downward trend.(3)The tend partial filling technology in fully mechanized caving mining adopts coal gangue,fly ash,cement and water-type paste filling materials,and the effect of ratio on the rheological properties of the material is studied by using the method of slump conversion yield stress.At the same time,the variation law of uniaxial compressive strength of the filling body under the combination of proportion and curing age was studied.The orthogonal material method was used to obtain the ratio of the superior material to the quality of fly ash and cement.:3,the mass ratio of vermiculite to cement is 1:7,and the mass fraction is 75wt.%.(4)Conducting industrial tests in Qinggangping Coal Mine,and designing the production system and filling system matched with this method,successfully mining thick coal seams with a thickness of 8.5m under the aquifer.The field measurement data indicates that the filling effect is better.it is good.