Study On Numerical Simulation Of Water Injection In Divided Seam Based On Fault Structure-coal Fracture Characteristics

As a widely used wetting technology,coal seam water injection plays a very good dust suppression role because it effectively encapsulates every small part of coal body,and then changes the physical and mechanical properties of coal body.At the same time,water into the coal body,so that the coal structure becomes loose and easy to cut off,reducing the risk of rock burst and coal shock caused by the collapse of the mine.However,as a comprehensive disaster control technology,coal seam water injection is lack of comprehensive and systematic research.Especially in the process of working out the engineering plan,it is unable to quantify and analyze the effect of the fault and coal fracture on the water injection effect,which results in the poor water injection effect of coal seam in China.Therefore,in this paper,combined with mine rules and reference to a large number of triaxial compression experiments,the complex geological structure of coal mine disassembled as a basic crack,and one by one in different geological structure on the effect of water injection.At the same time,a coal body model with a large number of mining cracks is established to accurately simulate the effect of water injection in the near coal face by MATLAB.According to the actual situation of the mine,the zoning injection scheme is designed,and the simulation analysis of the injection effect is carried out,and the quantitative distribution and variation results of the seepage field of pressure,velocity and water increment are obtained.The results show that the increase of water content is obviously higher than that of other areas when the fracture takes place turning,crossing and penetrating the water injection hole.Compared with non-prefabricated fractured coal,82.78 m3 of single hole water injection and 70,94 m3 of single hole water injection are increased in prefabricated flat fractured coal under 15 MPa pressure in 120 hours.The distribution of water increment field,seepage pressure field and seepage velocity field are basically the same in the early stage of water injection,and with a large number of primary cracks being soaked by water,the cracks play a role of water storage,but also accelerate the wetting speed of nearby coal.The research results are applied in the main research mines.The practice shows that the porosity of coal seam can be increased from 3.6%to 5.7%before and after zone injection.The volume of single hole water injection is increased from less than 70 m3 of the traditional water injection at home and abroad to 132 m3;Water content of coal body increased from 2.8%to 4.2%.The dust-lowering rate of coal mining,shifting and falling coal dust with high concentration can reach 61.36%,68.75%and 61.48%after water injection.Then,the research results of this paper will be extended to other mine fully-mechanized face for application,also achieved a good dust-reduction effect.