Research On Subsidence Control Technology For Underlying Coal Mining In Hongyanhe Reservoir

With the continuous development of China’s national economy,site selection planning for large-scale energy,transportation,water conservancy and hydropower projects often produces overlapping pressures with coal mining subsidence areas.Overburden deformation and breakage induced by mining geological disasters in coal mining subsidence areas have caused infrastructure construction.And operations pose a major security threat.Therefore,it is necessary to carry out research on the law of overburden movement,disaster mechanism and comprehensive prevention and control technology in coal mining subsidence area.In this paper,based on the treatment project of coal mining subsidence area under Hongyanhe Reservoir,the development law of overburden cracks in 8712fully mechanized top coal caving subsidence area of Huoshizui Coal Mine using theoretical analysis,wave velocity logging,water pressure experiment and numerical simulation,etc.The stability of the coal mining subsidence area under the load of the reservoir and the comprehensive prevention and control technology have been studied,and the following research results have been achieved:（1）Based on the theory of overlying rock migration and transfer,the formula for calculating the development height of the water guide fissure zone in fully mechanized caving mining is deduced,and the maximum development height of the water guide fissure zone in the 8712 working face is calculated to be 129m.The high value is 135.3m,and the cracking ratio is 19.05,which is basically consistent with the theoretical calculation.（2）Drilling wave velocity test and water pressure test show that the rock mass integrity at the edge of coal mining subsidence area is damaged to varying degrees,and the permeability is obviously enhanced.The water body in the reservoir area seeps downward along the stretched fissure zone at the edge of the subsidence basin,replenishes the overburden aquifer,and forms a hydraulic channel through the indirect communication between the primary fissure,mining fissure and the water-conducting fissure zone.Coal mine production operations pose a major security threat.（3）Based on the topography and stratum lithology of the reservoir area,a three-dimensional geological numerical model was constructed using the Rhino^3D-FLAC³DD coupling technology to study the movement and deformation law of overburden rock during the fully mechanized caving process and the stability of the coal mining subsidence area under the load of the water body in the reservoir area.The results show that the maximum development height of the water-conducting fissure zone in the 8712 working face is 138.24m,which is in good agreement with the actual measured values.Under the load of the reservoir,the vertical displacement of the ground surface increases by 334.7mm,and the development height of the water-conducting fissure zone increases by 3.76m,which poses potential safety hazards for the operation of the reservoir.（4）A comprehensive evaluation index system of coal mining subsidence area management technology was established through system engineering.Based on the stability analysis and disaster-causing mechanism of coal mining subsidence area under the reservoir,combined with the fuzzy analytic hierarchy process,it was proposed that The comprehensive prevention and control technology of regional anti-seepage and monitoring and early warning affecting the area.Engineering practice shows that the results of this research can effectively guarantee the operation safety of Hongyanhe Reservoir and Huoshizui Coal Mine,and have reference value for the prevention and treatment of geological environmental disasters in similar mines.