During the coal and rock mass fracture process, elastic properties are released and vibration waves are radiated outward. The energy attenuation characteristics of these waves can describe the ...cumulative damage and elastic energy accumulation of the mass. To investigate coal and rock mass failure characteristics and energy attenuation rules during rockburst, numerical simulation and laboratory testing were utilized to study the energy transfer laws under various parameters. Six variables, including elastic modulus, Poisson's ratio, bulk density, cohesion, internal friction angle, and void ratio, were selected to simulate the rockburst energy release process under different parameter combinations by adding surface pressure to the model. The coal and rock mass energy attenuation coefficient was obtained by fitting the node energy straight line using the least squares method. The six variables' influence on vibration wave energy transfer was obtained using analytic hierarchy process program written in MATLAB, and a comprehensive calculation formula was proposed. Using the energy attenuation coefficient, the rock layer energy diffusion distance was calculated and compared with the roof collapse rock layer step distance, resulting in the roof rock layer cutting distance determination. By roof rock strata precutting, rockburst occurrence can be prevented, ensuring safe and efficient coal mine production.
In recent years, with the increasing of mining depth and mining intensity, coal and gas outburst has become one of the most destructive and harmful dynamic disasters in coal mines. Natural ...earthquakes are the most destructive natural disasters in the earth’s crust. Both of coal and gas outbursts and natural earthquakes are caused by geo-dynamic processes. In order to research the correlation between coal and gas outburst and natural earthquake, in this manuscript, we took Pingdingshan eastern mining area as the research object. The principles of disaster prevention, seismology, statistics and geophysics were taken as the research basis, both the characteristics and laws of natural earthquakes, and the occurrence laws and characteristics of coal and gas outburst were systematically analyzed by geo-dynamic division method. At the same time, the relationship between the two disasters were established. The research results show that natural earthquake is the accumulation and release process of elastic properties in rock mass, which can induce the abnormal emission of gas in coal mines under specific conditions. Especially the “weak plane structure” in geological structure, which is more likely to lead to the occurrence of coal and gas outburst accidents. Tectonic activities and stress field changes have a unified mechanism for the occurrence of natural earthquake and coal and gas outburst, there are correlations between space and intensity. The research results can also provide new ideas for the prediction work of these two kinds of disasters.
Coal seams ascending mining technology is very significant, since it influences the safety production and the liberation of dull coal, speeds up the construction of energy, improves the stability of ...stope, and reduces or avoids deep hard rock mining induced mine disaster. Combined with the Xiaoming ascending mining mine 4-1, by numerical calculation, the paper analyses ascending mining 4-1 factors, determines the feasibility of ascending mining 4-1 coalbed, and proposes roadway layout program about working face, which has broad economic and social benefits.
The bursting liability of coal, referring to the characteristic of coal to accumulate strain energy and produce impact damage, is an important factor influencing the occurrence and extent of rock ...burst disasters in coal mines. Two indicatorsthe elastic strain energy storage coefficient and energy release coefficientare proposed based on the energy evolution characteristics of different stages during rock bursts. Twelve coal specimens from typical mines were selected for uniaxial compressive tests to analyze the damage characteristics of three types of typical coal specimens with different impact damage intensities in different loading stages. The initial kinetic energy of the coal specimens was obtained according to the principle of horizontal projectile motion. The bursting liability rating criteria according to the energy storage coefficient and energy release coefficient were determined based on the damage and motion characteristics of the coal mass, damage acoustic characteristics, and damage initial kinetic energy. The study demonstrated that the discrimination results based on the new criteria of coal mass bursting liability were consistent with the actual bursting liability level of the coal mass, thus providing a new method for determining coal mass bursting liability.
Coal burst tendency is the natural property of whether coal rock mass can have coal burst, and the distribution of fissures has an important influence on it. In order to study the influence mechanism ...of the original coal fissures on the energy dissipation characteristics and coal burst tendency, the PFC2D numerical simulation method was used to conduct uniaxial compression tests on coal specimens with different fracture types. The results show that: ①With the increase of the inclination angle of the fissure, the compressive strength and elastic modulus of the macroscopic mechanical parameters show a trend of decreasing first and then increasing; when the inclination angle of the fissure is 30, both of them reach the minimum value. The relationship between the macro-mechanical parameters of different fracture types is: non-coplanar parallel double-fissure specimen < single-fissure specimen < co-planar discontinuous double-fissure specimen.②The variation law of elastic strain energy and total strain energy is s
The ecological environment of semi-arid mining area is fragile with the severe site conditions, so it is difficult for the ecological reconstruction and vegetation restoration. Medicago. Sativa, as ...an important restoration plant, not only has strong resistance to stress, but also is useful to improve soil structure and nutrients. Thus, restoration model of planting M. Sativa plays an important role in vegetation restoration in semi-arid mining areas. To assess the effects of planting time on soil improvement, the evolution of soil particles fractal characteristics were studied by using methods of field stratified sampling and indoor measuring. Planting fields of M. Sativa with 2, 4, 6 and 10 years(M2, M4, M6 and M10) were selected as the research objects, while the new dump without planting and that with natural restoration were chosen as control treatment. Based on the particle size of fractal theory, the soil particles fractal characteristics of different planting years and its relationship with soil proper
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