Safe operation of underground reservoirs in coal mines is crucial for the coordinated exploitation of coal and water resources in western China.Mine water infiltration significantly influences the stability of the coa...Safe operation of underground reservoirs in coal mines is crucial for the coordinated exploitation of coal and water resources in western China.Mine water infiltration significantly influences the stability of the coal pillar.Therefore,laboratory tests were systematically carried out on coal from the Daliuta Coal Mine in Northwest China.Samples were taken in the vertical and parallel bedding directions and soaked for 0 d,2 d,4 d,or 16 d.In this study,atomic absorption spectroscopy(AAS),X-ray diffraction(XRD),and scanning electron microscopy(SEM)were used to analyze the variations in the water absorption characteristics and corresponding internal structure of the coal.Uniaxial compression tests and synchronous acoustic emission(AE)monitoring revealed the sample failure process and mechanical properties of the samples.Finally,the time-and frequency-domain characteristics of the AE signal were comprehensively analyzed using fractal dimension,fast Fourier transform,and cluster analysis.The strength and elastic modulus demonstrate significant anisotropy with different bedding planes and reveal the existence of the optimum water content.Specifically,the sample strength increases after 2 d of immersion,with increments of 23.3% and 0.6% for the vertical and parallel bedding samples,and decreases after 16 d of immersion,with decreases of 29% and 45% for the vertical and parallel samples,respectively.Additionally,shear cracks account for over 60% during the damage development of the samples.The proportion of tensile cracks is higher for samples with longer immersion times and parallel bedding planes.This research provides a theoretical basis for stability evaluation and protection of coal pillars in underground reservoirs using the AE technique.展开更多
Water–rock interaction(WRI)is a topic of interest in geology and geotechnical engineering.Many geological hazards and engineering safety problems are severe under the WRI.This study focuses on the water weakening of ...Water–rock interaction(WRI)is a topic of interest in geology and geotechnical engineering.Many geological hazards and engineering safety problems are severe under the WRI.This study focuses on the water weakening of rock strength and its infuencing factors(water content,immersion time,and wetting–drying cycles).The strength of the rock mass decreases to varying degrees with water content,immersion time,and wetting–drying cycles depending on the rock mass type and mineral composition.The corresponding acoustic emission count and intensity and infrared radiation intensity also weaken accordingly.WRI enhances the plasticity of rock mass and reduces its brittleness.Various microscopic methods for studying the pore characterization and weakening mechanism of the WRI were compared and analyzed.Various methods should be adopted to study the pore evolution of WRI comprehensively.Microscopic methods are used to study the weakening mechanism of WRI.In future work,the mechanical parameters of rocks weakened under long-term water immersion(over years)should be considered,and more attention should be paid to how the laboratory scale is applied to the engineering scale.展开更多
The corrosion mechanism of 510L low alloy steel treated by acid-cleaned surface(ACS)and eco-pickled surface(EPS)techniques in three simulated solutions(S0:atmospheric environment;S1:soil environment;S2:industrial envi...The corrosion mechanism of 510L low alloy steel treated by acid-cleaned surface(ACS)and eco-pickled surface(EPS)techniques in three simulated solutions(S0:atmospheric environment;S1:soil environment;S2:industrial environment)and the influence of interaction between different corrosive anions on corrosion were investigated.The results show that the total corrosion rates of samples in three simulated solutions were in order of S2>S0>S1,which is simultaneously correlated with initial corrosion dissolution processes as well as after the formation of corrosion products.HCO3−will inhibit the initial corrosion owing to the formation of films,whereas HSO3−will accelerate the dissolutions of the matrix based on the synergistic action of HSO3−and Cl−.On the other hand,there is no significant difference in corrosion rates between the samples treated by ACS and EPS techniques.The EPS technique that is safe,reusable and environmentally friendly can be further widely used in future work.展开更多
基金supported by the National Natural Science Foundation of China(Grant Nos.52174084 and U23B20146)the Open Fund for State Key Laboratory of Water Resource Protection and Utilization in Coal Mining(Grant No.WPUKFJJ2022-07)。
文摘Safe operation of underground reservoirs in coal mines is crucial for the coordinated exploitation of coal and water resources in western China.Mine water infiltration significantly influences the stability of the coal pillar.Therefore,laboratory tests were systematically carried out on coal from the Daliuta Coal Mine in Northwest China.Samples were taken in the vertical and parallel bedding directions and soaked for 0 d,2 d,4 d,or 16 d.In this study,atomic absorption spectroscopy(AAS),X-ray diffraction(XRD),and scanning electron microscopy(SEM)were used to analyze the variations in the water absorption characteristics and corresponding internal structure of the coal.Uniaxial compression tests and synchronous acoustic emission(AE)monitoring revealed the sample failure process and mechanical properties of the samples.Finally,the time-and frequency-domain characteristics of the AE signal were comprehensively analyzed using fractal dimension,fast Fourier transform,and cluster analysis.The strength and elastic modulus demonstrate significant anisotropy with different bedding planes and reveal the existence of the optimum water content.Specifically,the sample strength increases after 2 d of immersion,with increments of 23.3% and 0.6% for the vertical and parallel bedding samples,and decreases after 16 d of immersion,with decreases of 29% and 45% for the vertical and parallel samples,respectively.Additionally,shear cracks account for over 60% during the damage development of the samples.The proportion of tensile cracks is higher for samples with longer immersion times and parallel bedding planes.This research provides a theoretical basis for stability evaluation and protection of coal pillars in underground reservoirs using the AE technique.
基金the National Natural Science Foundation of China(52104155)Natural Science Foundation of Beijing(8212032)Fundamental Research Funds for the Central Universities(2023YQNY).
文摘Water–rock interaction(WRI)is a topic of interest in geology and geotechnical engineering.Many geological hazards and engineering safety problems are severe under the WRI.This study focuses on the water weakening of rock strength and its infuencing factors(water content,immersion time,and wetting–drying cycles).The strength of the rock mass decreases to varying degrees with water content,immersion time,and wetting–drying cycles depending on the rock mass type and mineral composition.The corresponding acoustic emission count and intensity and infrared radiation intensity also weaken accordingly.WRI enhances the plasticity of rock mass and reduces its brittleness.Various microscopic methods for studying the pore characterization and weakening mechanism of the WRI were compared and analyzed.Various methods should be adopted to study the pore evolution of WRI comprehensively.Microscopic methods are used to study the weakening mechanism of WRI.In future work,the mechanical parameters of rocks weakened under long-term water immersion(over years)should be considered,and more attention should be paid to how the laboratory scale is applied to the engineering scale.
基金supported by Key Scientific Research Project in Shanxi Province(Grant Nos.202003D111001 and 202102050201010)Fundamental Research Program of Shanxi Province(Grant No.202103021223293)+3 种基金National Natural Science Foundation of China(Grant No.52071227)Scientific Research Fund of Taiyuan University of Science and Technology(Grant No.20202044)Award Fund for Outstanding Doctors in Shanxi Province(Grant No.20212041)Postgraduate Education Innovation Project of Shanxi Province(Grant Nos.2022Y686 and 2022Y684).
文摘The corrosion mechanism of 510L low alloy steel treated by acid-cleaned surface(ACS)and eco-pickled surface(EPS)techniques in three simulated solutions(S0:atmospheric environment;S1:soil environment;S2:industrial environment)and the influence of interaction between different corrosive anions on corrosion were investigated.The results show that the total corrosion rates of samples in three simulated solutions were in order of S2>S0>S1,which is simultaneously correlated with initial corrosion dissolution processes as well as after the formation of corrosion products.HCO3−will inhibit the initial corrosion owing to the formation of films,whereas HSO3−will accelerate the dissolutions of the matrix based on the synergistic action of HSO3−and Cl−.On the other hand,there is no significant difference in corrosion rates between the samples treated by ACS and EPS techniques.The EPS technique that is safe,reusable and environmentally friendly can be further widely used in future work.
