Study on the rupture characteristics and stress-triggering mechanism of strong mine earthquake in huge thick strata
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CAO Anye,
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YANG Yao,
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HE Hu,
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YANG Yaoxin,
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BAI Xianxi,
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GU Qianyue,
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LI Songhui,
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FU Xiangchao,
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GU Yingshi,
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WU Zhen,
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ZHANG Di
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Graphical Abstract
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Abstract
Objective The huge thick strata is broken in deep coal mining, resulting in frequent mine earthquake (ME) that cause surface seismic sensation, has become a constraint on the efficient production of the mining area of the most serious problems, urgently need to change the current situation of high frequency, prevention and control of ME in the complex depositional environment of the mine stratigraphy. Methods Taking the frequent occurrence of ME in a working face in Hughilt mining area of the mining area as the research object, characteristics of structural breakage of huge thick strata solved by applying thick plate theory, based on the analysis and extraction of the main components of waveforms, the moment tensor inversion method was adopted to analyze the rupture mechanism of the ME source, and based on the modification of the stress inversion model for the principal stresses of tension, compression and mixed rupture seismic source, stress inversion algorithm was improved, and the characteristics of the breeding rupture of ME source and the evolution law of the stress field were analysed, so as to quantify and analyse the triggering mechanism of the stresses of the ME. Results and Conclusions The results show that the fracturing of huge thick strata provided the impetus and energy for the ME. The principal component analysis method can quickly extract the principal components of the waveforms disturbed by the mining environment, and provide high-quality inversion data for the moment tensor solution; the modified stress inversion algorithm can meet the demand for mining-induced non-shear rupture source stress inversion, and realise the inversion of the stress field of a typical non-shear rupture source such as a tensile or compressive ME source. During the workface mining period, the roof plate was broken layer by layer upwards and linked with the lateral air-mining zone, and the influence of the goaf made the roof plate activity increase before the occurrence of the mining earthquake, and the fracture characteristics of the huge thick strata as showed significant tensile state. The orientation of the principal stress during the process of the ME is basically the same, the R values of the stress shape factor are 0.66, 0.71 and 0.30, respectively, and the stress distribution has changed from uniaxial extrusion to extrusion-tension state, and the uniaxial extrusion of the maximum principal stress leads to the release of a large amount of elastic energy by transient fracture of the huge thick strata, which is the main reason for the “2.6” and “10.30” ME. The working face mining adjacent to larger goaf, the maximum and minimum principal stress of extrusion and tension synergistic effect will lead to a greater energy level of ME occurrence. The conclusions of the study can provide theoretical support for the mines in and around the mining area, which are restricted from efficient production due to the ME problem, to reduce the ME energy and reduce the frequency of ME from the aspect of stress regulation.
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