Study On Gas Migration Law And Emergency Disaster Prevention During Coal And Gas Outburst

Coal and gas outburst(outburst in short)is a kind of gas dynamic disaster when a large amount of coal and gas flood into the working space of coal mining operations within a short time.With the exploitation of deep resources,coal and gas burst has brought more and more harm to people and the society.In case of coal and gas outburst,much coal and gas will flood into under workings,leading to gas natural ventilation pressure.This has seriously disturbed the stability of ventilation systems in the mine and system security.The combined action of gas natural ventilation pressure and vector ventilation will break the original dynamic balance of air flow in the mine ventilation system,leading to risks such as backflow in the inlet tunnel and overflow in the return tunnel.This will make it more complicated to move gas the shaft system and more disaster areas of the mine will be affected.In order to research the influence of gas natural ventilation pressure on air flow in pipelines,a 14-m portable adjustable pipeline experimental test system with large height difference,low density and nonuniform air flow imbalance was built according to Froude similarity criterion.Rubber pipes with the diameter of 20 mm were used in the experiment and they were divided into three branches: the inlet pipe,the return pipe and the protrusion pipe.The helium-oxygen “double gas” replaces the place of mine gas,so as to create “low density” disaster underground environment.An oxygen sensor is used as the gas concentration sensor.Changes of the oxygen can reflect changes of helium in the pipeline.This proves the influence of gas natural ventilation pressure on airflow in tunnels.Besides,when there are same burst quantity and same burst time,gas natural ventilation pressure will affect the ventilation system.When there is gas natural ventilation pressure,gas can affect the burst air flow for longer time compared with the scene with no gas natural ventilation pressure.This is more obvious in complex mine systems.gas natural ventilation pressure will generate compression and sparse waves and different fluctuation laws will appear in air inlet and return tunnels.Besides,the fluctuation peaks tend to decrease gradually.The experimental analysis shows that after coal and gas outburst,the transmission of outburst strength,air flow,toxic and harmful gases and other disaster causing factors will affect the ventilation system of the mine.The analysis of dynamic laws of disaster causing factors in complex network domains is important to determine emergency decisions of mine ventilation system.TF1M3 D simulation platform can simulate and reproduce the whole process of coal and gas outburst disasters and determine the disaster effects of gas outburst in complex mine system networks.Based on factor characteristics of coal and gas outburst disaster network domains,a composite network domain model of active wind network with the “trinity” of spatial geometry,physics and environment is built.Accidents are simulated and represented in combination of the case of "11·21" coal and outburst accident in Xinxing mine.Besides,based on the disaster evolution law and disaster scope for gas migration-dispersion(diffusion),the quantitative model of probability and statistics and the information entropy theory is used to have a quantitative research on risk characteristics of gas accumulation in ventilation network area during the disaster period.Besides,a method to calculate gas concentration information entropy in tunnels during the disaster period is put forward and a theoretical system for gas accumulation risks in ventilation network areas based on information entropy is established.The numerical simulation of disaster process provides a reference for intelligent decision-making of mines.The theoretical system of gas accumulation risk information entropy can provide dynamic feedback for underground emergency schemes and guide the formulation of disaster avoidance routes.Besides,the ant colony algorithm is used to determine the shortest disaster avoidance route and the gas concentration information entropy is used to optimize the route so as to obtain the optimal disaster avoidance route in the prominent burst period.There are 70 pictures,20 tables and 160 references in the dissertation.