Focal Mechanism of Strong Ground Seismicity Induced by Deep Coal Mining

Induced seismic activity and source parameter characteristics in the Datong coal mine, China

“…The seismic source rupture radius r is a physical quantity that describes the scale of the rupture surface generated by the seismic source rupture, reflecting the disturbance scale of the coal-rock mass in coal mining. In this study, the calculated rupture radius r values range from 72 to 271 m. This finding is consistent with the results of other studies on the calculation of the coal mine microseismic rupture scale (Chen et al, 2019(Chen et al, , 2021a(Chen et al, , 2021bWu et al, 2023).…”

“…The analysis of the corner frequency and stress drop results shows that the corner frequency and stress drop of mining-induced earthquakes in the Datong mining area are significantly lower than those of tectonic earthquakes of the same magnitude. Recent studies on coal mining-induced mine earthquakes have also confirmed this conclusion (Chen, 2019; Chen et al, 2021a, 2021b; Wu et al, 2023; Zhou et al, 2020), indicating that the rupture scale and form of mining-induced earthquakes in Datong coal mines are different from those of natural earthquakes. This finding is attributed mainly to the artificial alteration of the originally stable geological structure and stress environment during coal mining.…”

Study of Time-Varying Laws of Stability and Wettability of SiO2–H2O Nanofluids with Different Particle Sizes

“…The potential energy of electrostatic repulsion U R between two spherical particles can be expressed as (5) The sedimentation force F 1 on particles can be expressed as (6) According to Stokes' law, the sedimentation resistance F 2 on particles is (7) When particles are suspended or fall uniformly, there is (8) Then, the rate of sedimentation v 0 of particles is expressed as (9) where A is the Hamaker constant; d is the particle diameter; H is the spacing between particles; ε is the relative dielectric constant of the base solution; φ 0 is the surface potential of particles;…”

“…Coal, as one of the important fossil energy resources, is an essential resource in the industrialization and urbanization processes. − In recent years, shallow resources have been gradually depleted with the growing mining intensity, and deep mining has become normal. − However, deep underground mines feature great geostress and high gas concentration, so the gas content is likely to exceed the limit and gas disasters including rock and gas outbursts occur frequently. , Water injection in coal seams is one of the effective measures to control gas and has been extensively applied to coal mining. − Injecting high-pressure water in coal seams through boreholes to wet and soften coal seams before mining can distribute stress uniformly, enhance the plasticity of coal, and reduce the release of elastic potential energy, thus further eliminating or decreasing the risk of coal and gas outbursts, − whereas numerous research studies have shown that coal has strong hydrophobicity and deep coal seams have poor gas permeability, so water is difficult to absorb by coal seams. This may lead to waste of a huge amount of water resources and a poor water injection effect. − Therefore, increasing the wettability of coal seams is the key to improving the water injection effect in the coal seams.…”