Research On Situation Assessment And Early Warning Of Coal And Gas Outburst

Coal and gas outburst is one of the major disasters in threatening coal mine safety production.As the coal mining grows deeper,the danger,intensity and frequency of coal and gas outburst all keep increasing,that occasionally cause gas outburst accidents.In accordance with the technical problems of coal and gas outburst prevention,based on the mechanism of coal and gas outburst,relevant theories are applied.The relevant theories are monitoring theory,situation assessment theory,early warning theory,modern information science and technology theory and mining safety theory etc.According to the field investigation and deep theoretical research,simulation tests by computer and field tests are applied to study the theory and realization method of situation assessment and warning for coal and gas outburst.According to coal and gas outburst mechanism and gas emission regularity,the situation of gas concentration is analyzed in working face.The results show that as the face advances,gas concentration changes in time and space,and that can be quantitatively analyzed using trend and fluctuation as evaluation index.Meanwhile,the gas concentration is predicted through establishing time series prediction model and semi-parametric estimation model about multiple influencing factors of gas concentration.During the fracture of coal and rock,it will generate acoustic emission,electromagnetic radiation and charge radiation,and its mechanism,development and signal characteristics are analyzed.Then the identification method of precursor signal is proposed,and the identification of that is simulated.The results show that this method can effectively filtering background noise,identifing useful signals,and improve the signal-to-noise ratio.In order to detect the weak charge signal in the process of coal and rock fracture,The induction probe and induction amplifier for charge are developed.The stress loading test mass is carried out for coal and rock by hammering.The test results show that with the increase of the acquisition area for the charge induction probe,the material conductivity,collected chargers and the output effect of charge induction amplifier increase.Experiments show that#4 charge sensing probe has the best effect.The situation sssessment of gas outburst is invstigated.The structure model of gas outburst situation assessment is established to extract and classify its state set elements.Based on local feature time-frequency analysis method of variational mode decomposition,dynamic prediction model and interval prediction model of state set slements are estblished.An evidence fusion reasoning of gas outburst situation assessment with improved weight is proposed.The goals are to provide a solid theoretical basis and analysis method for outburst situation assessment.The gas concentration situations are evaluated,by establishing ingle-element and single-category assessment models of gas outburst situation assessment,and taking the environmental characteristic elements as the research object.The results show that the single-category assessment model takes more factors into account in the actual environment,and the assessment results of gas concentration situation are consistent with the actual situation.The comprehensive situation assessment model of gas outburst is established to verify its effect.The results show that the model is effective and consistent with the actual situation.Meanwhile,taking the monitoring data of working face as the research object,a comprehensive situation assessment model is established to evaluate the gas outburst situation in front of working face,that can provide the corresponding warning level.The results show that warning in advance of outburst danger can avoid the omission caused by a single method and improve the early warning accuracy.