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巨厚覆岩矿震孕育破裂特征与应力触发机制

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[目的]深部开采巨厚覆岩破断导致引起地表震感的矿震频发,已成为制约矿区高效生产的最严峻难题,亟待改变矿区巨厚覆岩矿震频度高、防控难现状.[方法]以内蒙古自治区鄂尔多斯呼吉尔特矿区某邻空综采工作面频发巨厚覆岩矿震为研究对象,应用厚板理论分析巨厚覆岩结构破断演化规律,提取矿震波形主成分并采用矩张量反演方法定量研究矿震震源破裂机制,基于张拉、压缩及混合破裂震源主应力作用方式修正应力反演模型,改进应力反演算法,分析矿震震源孕育破裂特征及应力场演化规律,定量解析矿震应力触发机制.[结果和结论]结果表明,巨厚覆岩破断运移为矿震孕育触发的动力、能量源;主成分分析方法可快速提取因采矿环境干扰波形的主成分,为矩张量求解提供优质反演数据;修正后应力反演算法能够满足采动诱发非剪切破裂震源应力反演需求,实现对典型张拉、压缩等非剪切破裂矿震震源应力场反演;工作面邻空回采期间,顶板逐层向上与侧向采空区联动破断,采空区影响使得孕震期间顶板活动性增强,巨厚覆岩断裂特征整体呈显著张拉状态;矿震孕育过程中主应力作用方位基本一致,应力形因子分别为 0.66、0.71和 0.30,覆岩应力分布由单轴挤压转变为挤压张拉状态,最大主应力单轴挤压作用导致巨厚覆岩瞬时断裂释放大量弹性能是诱发"2·6"和"10·30"矿震的主要原因,工作面邻更大范围采空区开采,最大、最小主应力挤压张拉协同作用将可能诱发更大能级矿震.研究结论可为矿区及周边因矿震问题限制高效生产的矿井从源头调控降载减震提供理论支撑.
Fracturing characteristics of significantly thick overburden inducing mine earthquakes and the stress-triggering mechanisms of the mine earthquakes
[Objective]Frequent mine earthquakes that cause surface seismaesthesia,induced by the fracturing of signi-ficantly thick overburden in deep coal mining,are identified as the most severe challenge to the efficient production of mining areas.There is an urgent need to overcome the current difficulty caused by mine earthquakes induced by signific-antly thick overburden,which feature high frequency and challenging prevention and control.[Methods]Using such mine earthquakes occurring in a certain fully mechanized mining face adjacent to goaves in the Khujirt mining area in Ordos,Inner Mongolia Autonomous Region,as an example,this study(1)analyzed the evolutionary patterns of structur-al fracturing of the significantly thick overburden based on the thick plate theory;(2)extracted the principal components of mine earthquake waveforms and quantitatively explored the fracturing mechanisms of seismic sources using the mo-ment tensor inversion method;(3)corrected the stress inversion model and algorithm based on the acting mechanisms of principal stresses acting on seismic sources subjected to tensile,compressive,or mixed-type fracturing;and(4)analyzed the fracturing characteristics of the sources of mine earthquakes and the evolutionary patterns of stress fields and quantit-atively analyzed the stress-triggering mechanisms of the mine earthquakes.[Results and Conclusions]The results indic-ate that the fracturing and migration of the significantly thick overburden provide impetus and energy for the formation and triggering of mine earthquakes.The principal component analysis method can quickly extract the principal compon-ents of the waveforms disturbed by mining environments,thus providing high-quality inversion data for solving the mo-ment tensor.The corrected stress inversion algorithm satisfied the requirements for the stress inversion of seismic sources subjected to mining-induced non-shear fracturing,thus allowing for the inversion of stress fields of typical seis-mic sources subjected to tensile/compressive fracturing.The mining along the mining face adjacent to goaves caused the roofs,along with lateral goaves,to fracture upwards layer by layer.Under the influence of goaves,the roof activity in-tensified during the formation of mine earthquakes.The fracturing characteristics of the significantly thick overburden generally manifested a significant tensile state.During the formation of mine earthquakes,principal stresses exhibited roughly consistent orientations,with stress shape factors of 0.66,0.71,and 0.30.The stress distribution of the overbur-den transitioned from uniaxial compression to a compressive-tensile state.The uniaxial compression of the maximum principal stress led to the transient fracturing of the significantly thick overburden.This was accompanied by the release of significant elastic energy,which served as the primary cause of the February 6 and October 30,2021 Hujierte mining area earthquakes.In the case of the mining face adjacent to large goaves,the synergistic effects of compression and ten-sion under the maximum and minimum principal stresses may induce mine earthquakes with higher magnitudes.For mines whose efficient production is restricted by mine earthquakes,the conclusions of this study will provide theoretical support for adjusting loads and reducing mine earthquakes from sources.

significantly thick overburdenmine earthquake formationfracturing mechanismstress inversiontrigger-ing mechanism

窦林名、曹安业、杨耀、贺虎、杨垚鑫、白贤栖、顾倩悦、李松徽、付相超、顾颖诗、吴震、张帝

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中国矿业大学 矿业工程学院,江苏 徐州 221116

中国矿业大学 深部煤炭资源开采教育部重点实验室,江苏 徐州 221116

中国矿业大学 江苏省矿山地震监测工程实验室,江苏 徐州 221116

中国矿业大学资源与地球科学学院,江苏 徐州 221116

国家矿山安全监察局内蒙古局,内蒙古 呼和浩特 010010

内蒙古昊盛煤业有限公司,内蒙古 鄂尔多斯 017000

中煤能源研究院有限责任公司,陕西 西安 710054

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巨厚覆岩 矿震孕育 破裂机制 应力反演 触发机制

国家重点研发计划项目江苏省创新支撑计划国际科技合作/港澳台科技合作-重点国别产业技术研发合作项目国家自然科学基金项目

2022YFC3004603BZ202305052274098

2024

煤田地质与勘探
中煤科工集团西安研究院

煤田地质与勘探

CSTPCD北大核心
影响因子:1.079
ISSN:1001-1986
年,卷(期):2024.52(10)
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