Research On Narrow Strip Paste Filling Mining Technology In CT301 Working Face Of Mahuangliang Coal Mine

In recent years,due to the increasing shortage of coal resources in China,and in order to protect the surface buildings in Yulin area of Shanxi Province,mining methods of 9 m and 12 m are generally adopted,resulting in a large number of retained coal pillars,resulting in low recovery rate of coal resources and serious waste of resources.In order to further improve the resource recovery rate,prolong the service life of the mine,and construct an ecologically civilized mining area,the narrow strip paste filling mining technology was studied and put forward.Based on the research of paste backfilling mining in CT301 working face of Mahuangliang Coal Mine,aiming at the actual situation of large coal pressure under buildings and low recovery rate,this paper puts forward the narrow strip paste backfilling mining technology.By means of theoretical analysis and numerical simulation,the deformation and stress characteristics of surrounding rock in narrow strip mining and filling process are analyzed,the bearing characteristics and long-term stability of paste filling body are discussed,and the strength index of filling body is put forward.The composition of paste filling material is studied preliminarily,and the following main conclusions are obtained preliminarily:(1)The mechanical model of retaining beam is established,and the important parameters of narrow strip paste filling in CT301 face of Mahuangliang Coal Mine are obtained by theoretical analysis and calculation,that is,the width of narrow strip is set to 8 m,the width of coal pillar is set to 24 m,and the whole mining process is divided into four rounds.The strength of filling body necessary for mining safety is not less than 4.9 MPa.(2)Based on the geological conditions of Mahuangliang Coal Mine,a numerical simulation model was established.The rationality of the conclusions obtained from the theoretical analysis is verified by numerical simulation analysis,and the rock pressure behavior law of the surrounding rock after the first round of filling in narrow strip mining under the premise that the strength of filling body is 5 MPa.(3)The feasibility of no filling scheme after the fourth round of narrow strip mining is discussed.Compared with the results of all filling,the roof subsidence increased from 110 mm to 180 mm,with an increase of 64%.Although the increase is large,it can still maintain the long-term stability of the roof.(4)According to the existing situation of local raw materials,five kinds of gypsum materials(fly ash gypsum,gangue gypsum,gangue-fly ash gypsum,gangue-loess gypsum,aeolian sand-loess gypsum)are put forward,that is to say,their optimum proportion is obtained through experiments.The research results of this paper not only provide a new way to solve the problem of coal reserves under buildings,but also play a good role in promoting the promotion of green mining in the country.