Study On Pressure Mining Technology Of 10115 Working Face Above Confined Water In Tongting Coal Mine

The coal seam points threatened by floor limestone water in China are widely distributed,and with the increase of mining depth,the water pressure increases,the risk increases,and the risk of water inrush increases significantly.The 10115 working face of Tongting Coal Mine is threatened by the limestone water in the floor.The mining area is located between-480～-590m.The static water level of the limestone aquifer is+4.41m.The water pressure is as high as 4.85～5.94MPa before drainage and pressure reduction,which is the mining face under pressure.The calculated water inrush coefficient before drainage and pressure reduction is 0.072～0.089MPa/m.It has the prominent characteristics of close distance,high water pressure,uneven water rich,large water inrush coefficient and many fault structures.If effective measures are not taken,the water inrush coefficient can not meet the requirements of’coal mine water prevention and control rules’,and there is the possibility of water inrush.Therefore,it is necessary to carry out the research on the pressure mining technology of 10115 working face above the confined water in Tongting Mine.Based on the research background of 10115 working face above high confined water in Tongting Coal Mine of Huaibei Mining Group,aiming at accurate mining and green safe mining,this paper analyzes the hydrogeological conditions and engineering geological characteristics of the working face on the basis of consulting the latest research results and cutting-edge technologies of dewatering and depressurization mining technology above confined water in deep buried coal seams at home and abroad.The underground transient electromagnetic method,direct current method and audio frequency electric perspective are designed and constructed to obtain the geophysical low-resistance water-rich anomaly area,and the water-richness of the geophysical anomaly area is verified by drilling.The rock core was taken,and the rock micro-composition analysis and physical and mechanical properties experiments were carried out in the laboratory.The water barrier characteristics of the floor rock layer were obtained,and the evolution model of the mining floor failure analysis was constructed.The FLAC^3Dnumerical software was used to simulate the evolution law of the floor failure during the mining process of the working face.The design and implementation of underground long borehole along the layer,rapid drainage of floor limestone water affecting safe mining,greatly reducing the water pressure,to achieve low pressure and even zero pressure mining.The main research contents and achievements are as follows:（1）The 10115 working face is located in the 1011 mining area of Tongting Coal Mine.The strike length is 516.00m,the tilt length is 150.00m,and the mining elevation is-480.00m～-590.00m.The main mining is 10 coal,with an average coal thickness of 3.20m.Comprehensive mechanized mining is adopted,all caving method is used to manage the roof,and the mining speed is 3.0m/d.（2）The direct water filling source of working face mining is 10 coal seam roof and floor sandstone fissure water;indirect water filling source is 10 coal floor limestone water;according to the analysis of ground drilling exploration data in and near the working face2021-15,2017-10,2015-9,the static water level elevation of limestone aquifer is+4.41m,the unit water inflow q=0.0000264～0.37714L/s.m,and the average distance between the bottom of the coal seam and the ash is 68m.The upper part is light gray silt-fine grained sandstone,which can help to curb the development of floor failure depth to the deep.The lower part is dark gray,dense,massive mudstone,with less developed cracks,good viscoplasticity and strong water resistance.（3）After the formation of the working face,the transient electromagnetic exploration of the roof was carried out.The overall apparent resistivity within the 70m range of the coal seam roof in the detection area was high,and the overall water abundance was weak.The direct current method was used to detect the floor and two relatively low resistance areas were found.One is located in the range of 390～460 m from the cut hole and 15～45 m below the roadway floor.One is located in the range of 490～510 m from the cut hole and40～80 m below the roadway floor.（4）The stress-strain curve of floor rock is obtained.It is analyzed that the structural bedding of mudstone and sandstone in the influence range of mining face is clear,the bedding is closely connected,the pore structure is simple,the pore is small,and the water barrier performance is good.（5）According to the borehole histogram around the working face and the lithology parameters obtained from the indoor rock mechanics test,the numerical model of the floor failure evolution law of the 10115 working face floor under the dual action of mining and water pressure is constructed,and the failure movement law of the working face rock stratum is analyzed.The simulation results show that the height of the plastic zone is stable at about 31.25m until it is pushed to 200m.（6）According to the characteristics of the working face,3720m/9 holes of directional drainage boreholes along the limestone strata were designed and constructed to quickly drain the limestone water in the floor and cover the roadway excavation.The water level of limestone has been reduced from+4.41m to-600m before mining,which is lower than the mining level elevation.The 10115 working face has gradually changed from high-pressure mining to low-pressure or zero-pressure mining.The maximum water inrush coefficient calculated after drainage and depressurization is 0.0447MPa/m,less than0.06MPa/m,which meets the requirements of’Coal Mine Water Control Rules’and has safe mining conditions.When the paper is completed,the 10115 working face has been safely mined 426m,and no water inrush accident has occurred.It shows that the paper adopts the bedding long borehole to quickly drain and reduce the pressure on the floor.The geophysical prediction,drilling verification,high pressure limestone water coal seam safety mining technology system is feasible and has wide application value.Figure 42 table 17 reference 85...