Prediction and prevention measures of the hottest

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Prediction and prevention measures of coal and gas outburst

1.1 mechanism of coal and gas outburst

many countries attach great importance to the research on the mechanism of coal and gas outburst and have made some achievements, but due to the complexity of outburst mechanism and the diversity of outburst phenomena, the understanding of outburst mechanism is still in the hypothesis stage. The foreign understanding of coal and gas outburst mechanism can be summarized into four kinds: in-situ stress hypothesis, gas action hypothesis, chemical essence hypothesis and comprehensive action hypothesis. Since the 1960s, China has carried out a series of studies on the stress state of outburst coal seams, gas occurrence state, physical and mechanical properties of coal, discussed the outburst mechanism based on field data and experimental research, and put forward new opinions and views, which are summarized as central expansion theory, rheological hypothesis, two-phase liquid hypothesis, solid fluid coupling instability theory, spherical shell instability theory, etc. In addition, the Institute of mechanics of Chinese Academy of Sciences has done a lot of research work on the outburst process from the perspective of mechanics, and put forward the mechanism equations of outburst failure process and gas seepage. Types of coal and gas outbursts

1.2 coal and gas outbursts include: coal and Methane Outburst, rock and Methane Outburst, coal and CO  2 outburst, rock and CO  2 outburst, etc. Due to the different driving forces and phenomena during outburst, she taught the purpose of classification of combustion performance of materials and products and the classification of combustion performance of foreign materials and products. Coal and gas outburst can be divided into three situations: outburst, dumping and extrusion

1.3 general law of coal and gas outburst

(1) the number and intensity of outburst increase with the increase of mining depth

the permanent theme of realizing 'innovation is you (refers to the ultimate consumer)' (2) it mainly occurs in geological structural areas, such as folds, faults and magma intrusion areas

(3) the more serious the damage degree of coal body is, the smaller the strength of coal is, and the greater the outburst risk is

(4) outburst is easy to occur in areas with large thickness and dip angle in coal seams, or where their thickness and dip angle change, and the soft stratification in coal seams changes from thin to thick

(5) outburst is easy to occur in the area with concentrated stress in the heading face

(6) under the impact of external forces, such as blasting or coal cutting machine, the coal body is vibrated, inducing gas outburst

(7) the worse the permeability of surrounding rock, the thicker the dense rock layer, and the higher the gas content of coal seam, the greater the risk of outburst

(8) outbursts mostly occur in coal uncovering and coal seam heading faces

(9) most of the signs appear before the outburst.

2 Prediction of coal and gas outburst

we should often pay attention to the problems found in the use of the experimental machine

2.1 classification of outburst prediction methods

according to the different prediction scope and time, the prediction methods can be divided into three categories: the first is regional prediction, mainly to determine the outburst risk of coal fields, coal mines, coal seams and mining regions; The second is local prediction, which is to further judge the prominent danger of local areas or key points on the basis of regional data, such as drilling and mining projects; The third is daily prediction, which is based on regional prediction and local prediction, and warns of prominent dangers according to various abnormal effects of prominent omens.

2.2 prediction methods of coal and gas outburst at home and abroad

2.2.1 prediction of outburst risk by microseismic technology

the research shows that rupture and vibration occur in the process of mechanical failure of coal and surrounding rock. When the intensity and frequency of seismic waves or sound waves from the source increase to a certain value, sudden destruction of coal and outburst may occur. The outburst is caused by several continuous faults, and the abnormal microseismic emission usually occurs within 5 ~ 45s before the fault, so the microseismic method, as a outburst prediction method, has a broad application prospect. Russia has made good research achievements in seismic acoustic prediction methods. 

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