Deformation of coals under tectonic movements could cause reduction of mechanical strength and enhancement of gas adsorption,which might result in coal and gas outburst,and cause safety and environmental issues.In thi...Deformation of coals under tectonic movements could cause reduction of mechanical strength and enhancement of gas adsorption,which might result in coal and gas outburst,and cause safety and environmental issues.In this study,geophysical characteristics of coals with various structures were investigated with a special emphasis on characterization of pore size distribution,rock mechanical strength,acoustic emission,resistivity and acoustic velocity of anthracites with three types of structures in the Qinshui Basin,north China.The studied No.3 coal seam developed three types of structures,namely undeformed coal,cataclastic coal,and granular coal.Petrographic observations under scanning electron microscope and pore size distribution using N2 and CO_(2) adsorption of anthracites of three types show that the undeformed coal consists of primary micropores,and cataclastic coal is mainly composed of mesopores and well-connected fractures.In comparison,granular coal has the least mesopores.Rock mechanical strength,acoustic emission,resistivity and acoustic velocity of coals with three structure types were investigated under uniaxial and triaxial compression.With increasing degree of deformation of anthracites,compression strength,Young’s modulus,density,acoustic emission counting and acoustic velocity decreases,while resistivity increases.We suggest that the evolution of pore size distribution of anthracites with increasing degree of deformation contributed to variations of geophysical characteristics of coals with different structures to some extent.展开更多
ongliao, Bohaiwan and Jianghan basins are typical rift basins in East China, whose geophysical characteristics are described as follows: (1) The trends of the regional gravity and magnetic field are dominantly NNE,...ongliao, Bohaiwan and Jianghan basins are typical rift basins in East China, whose geophysical characteristics are described as follows: (1) The trends of the regional gravity and magnetic field are dominantly NNE, which indicates that the fault network of the basement is NNE and NE. (2) The deep gravity anomalies are mirror reflection of the depression areas associating with high heat flow, which can be explained by the uplift of Moho surface in these basins. (3) The crust has twolayer structure consisting of granite and basalt rocks, and there exist highconductivity and lowvelocity layers in the crust and in the upper mantle. (4) The oil and gas enrichments are distinctly related to the degree of the asthenosphere upwelling and crust thinning and high heat flow.展开更多
The overburden failure causes the changes of the constant electric field, and the resistivity is the main parameter in these changes. The experimental simulation about tbe response relation between the overburden fail...The overburden failure causes the changes of the constant electric field, and the resistivity is the main parameter in these changes. The experimental simulation about tbe response relation between the overburden failure and its electrical parameter changes is made by building the similar material physics model of mining. The experiment results are used to analyze and test the in-situ detection. The research indicates that the resistivity changes with the electric characteristic of the rock in cracked zone and caving zone caused by overburden failure, the response characteristics of resistivity vary with the failure degrees at different overburden failure zone and that they are corresponding. The resistivity method used in monitoring the overburden failure can determine the height and the affecting scopes of the cracked zone and caving zone. This can provide reliable techaological guarantee for mining design and safe production.展开更多
基金supported by the National Natural Science Foundation of China(Grant No.42102194).
文摘Deformation of coals under tectonic movements could cause reduction of mechanical strength and enhancement of gas adsorption,which might result in coal and gas outburst,and cause safety and environmental issues.In this study,geophysical characteristics of coals with various structures were investigated with a special emphasis on characterization of pore size distribution,rock mechanical strength,acoustic emission,resistivity and acoustic velocity of anthracites with three types of structures in the Qinshui Basin,north China.The studied No.3 coal seam developed three types of structures,namely undeformed coal,cataclastic coal,and granular coal.Petrographic observations under scanning electron microscope and pore size distribution using N2 and CO_(2) adsorption of anthracites of three types show that the undeformed coal consists of primary micropores,and cataclastic coal is mainly composed of mesopores and well-connected fractures.In comparison,granular coal has the least mesopores.Rock mechanical strength,acoustic emission,resistivity and acoustic velocity of coals with three structure types were investigated under uniaxial and triaxial compression.With increasing degree of deformation of anthracites,compression strength,Young’s modulus,density,acoustic emission counting and acoustic velocity decreases,while resistivity increases.We suggest that the evolution of pore size distribution of anthracites with increasing degree of deformation contributed to variations of geophysical characteristics of coals with different structures to some extent.
文摘ongliao, Bohaiwan and Jianghan basins are typical rift basins in East China, whose geophysical characteristics are described as follows: (1) The trends of the regional gravity and magnetic field are dominantly NNE, which indicates that the fault network of the basement is NNE and NE. (2) The deep gravity anomalies are mirror reflection of the depression areas associating with high heat flow, which can be explained by the uplift of Moho surface in these basins. (3) The crust has twolayer structure consisting of granite and basalt rocks, and there exist highconductivity and lowvelocity layers in the crust and in the upper mantle. (4) The oil and gas enrichments are distinctly related to the degree of the asthenosphere upwelling and crust thinning and high heat flow.
文摘The overburden failure causes the changes of the constant electric field, and the resistivity is the main parameter in these changes. The experimental simulation about tbe response relation between the overburden failure and its electrical parameter changes is made by building the similar material physics model of mining. The experiment results are used to analyze and test the in-situ detection. The research indicates that the resistivity changes with the electric characteristic of the rock in cracked zone and caving zone caused by overburden failure, the response characteristics of resistivity vary with the failure degrees at different overburden failure zone and that they are corresponding. The resistivity method used in monitoring the overburden failure can determine the height and the affecting scopes of the cracked zone and caving zone. This can provide reliable techaological guarantee for mining design and safe production.
