| In 153 mining area of Hengda Coal Mine,the emission amount of gas is very high and the spontaneous combustion period is very short.In the process of slicing mining bounded by thin rock interlayer caused by magmatic intrusion,goafs of the upper and lower layers are connected in different degree,which causes serious threat of gas and spontaneous combustion for the mining area.In order to solve the above problems,theory of rock pressure and fracture development and gas migration accumulation mechanism and coal spontaneous combustion,the interactions effect of gas and spontaneous combustion and their control methods are studied through method of theoretical analysis,numerical simulation and field investigation.On the basis of idea and methods on gas and spontaneous combustion coordinated control,according to fracture connected state between the upper goaf and under working face,coal spontaneous combustion and gas control zones of 153 mining area are divided into non connected zone,local connected zone and fully connected zone.It constructs both mathematical and physical models of the upper layer working face to study interrelationship of gas and spontaneous combustion.It obtains 3D leakage field,gas concentration field,Oxygen concentration field and spontaneous combustion ‘three zones' distribution under no gas drainage conditions in working face.Meanwhile it analyses the 3D leakage field,gas concentration field,the drainage efficiency and spontaneous combustion ‘three zones' distribution under high roadway drainage,corner buried pipe drainage,high erect and ground borehole drainage.It gives parameter optimization and suggestions for combined drainage of high roadway,corner buried pipe and high erect borehole.And then it sets up mathematical and physical models for the below layered face complex stope to analyze interrelationship of the gas and spontaneous combustion.With the model simulation calculation,it analyses impacts of the changes of air volume,corner buried pipe drainage and high roadway drainage to gas concentration field,oxygen concentration field and temperature field in complete and local connected zones,which lays a theoretical foundation for further research on gas and spontaneous combustion zonal controlling effect and method in complex stope.Analyzing the grouting effect at the intake lane of working face,it finds that the measures can significantly weaken air leakage combustion in upper goaf near the stopping mining line and is helpful to strengthen high roadway drainage efficiency,but is not conducive to control of the spontaneous combustion in the goaf top of the working face.It also analyses cross impact of between high roadway and corner buried pipe jointly draining in respects of their gas drainage concentration variation with their drainage flow changing as while as the changes of gas concentration at upper corner and maximum gas concentration in the return roadway,which lays foundation for the establishment of multi point control benchmark.For Nitrogen injection in complete and local connected zones,control effect of spontaneous combustion and influences to drainage efficiency of high roadway and corner buried pipe,as well as gas concentration in upper corner and the maximum gas concentration in return air roadway are analyzed.It designs multi-point step Nitrogen injection for local connection zone.Based on control benchmark of spontaneous combustion control index(7% Oxygen)and gas in air control index(gas concentration 0.8%),the multi-point dynamic control method of coordinated control of gas and spontaneous combustion is established.And it identifies normal control parameters of gas and spontaneous combustion for working face 5333(B).The theory and technology are successfully practiced in 153 mining area of Hengda Coal Mine.The gas drainage rate is increased to 80% and the definition of gas concentration is reduced to 0.6%,which shows good results in gas and spontaneous combustion control. |
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