A comprehensive understanding of the failure behavior and mechanism of coal is a prerequisite for dealing with dynamic problems in mining space.In this study,the failure behavior and mechanism of coal under uniaxial d...A comprehensive understanding of the failure behavior and mechanism of coal is a prerequisite for dealing with dynamic problems in mining space.In this study,the failure behavior and mechanism of coal under uniaxial dynamic compressive loads were experimentally and numerically investigated.The experiments were conducted using a split Hopkinson pressure bar(SHPB)system.The results indicated that the typical failure of coal is lateral and axial at lower loading rates and totally smashed at higher loading rates.The further fractography analysis of lateral and axial fracture fragments indicated that the coal failure under dynamic compressive load is caused by tensile brittle fracture.In addition,the typical failure modes of coal under dynamic load were numerically reproduced.The numerical results indicated that the axial fracture is caused directly by the incident compressive stress wave and the lateral fracture is caused by the tensile stress wave reflected from the interface between coal specimen and transmitted bar.Potential application was further conducted to interpret dynamic problems in underground coal mine and it manifested that the lateral and axial fractures of coal constitute the parallel cracks in the coal mass under roof fall and blasting in mining space.展开更多
Accurately revealing the spatial distribution law of seismic displacement is signifcance for revealing the mechanism of dynamic load induced rockburst and guiding the dynamic support of roadway.This paper established ...Accurately revealing the spatial distribution law of seismic displacement is signifcance for revealing the mechanism of dynamic load induced rockburst and guiding the dynamic support of roadway.This paper established the function of seismic displacement based on radiation energy,and compared the infuences of fracture type,radiation energy,shear strength,fracture velocity and medium density on the seismic displacement.The results showed that the displacement amplitudes of surrounding rock caused by P-wave,SH-wave and SV-wave increased with the rising of radiation energy,and the rate of displacement amplitude also accelerated.The displacement amplitudes of seismic wave associated with tensile fractures are signifcantly higher than that with shear fractures.The spatial displacement amplitude of S-wave was signifcantly higher than that of P-wave by one order of magnitude.The peak value of P-wave displacement of shear fracture was concentrated in two planes at 45°angle to the fracture surface.For SH-wave and SV-wave components,peak values were mainly observed on the fracture surface and its orthogonal plane.The P-wave displacement on the orthogonal plane to the fracture movement was zero,the displacement feld of SV-wave was distributed in four quadrants,and the displacement feld of SH-wave was symmetrical.The higher the value of medium attribute,the more signifcant the damage efect of coal-rock seismic wave weakening,and the infuence on the S-wave is greater than that of the P-wave.The displacement amplitude caused by seismic wave gradually increased with the rising of fracture velocity of coal-rock mass.The peak value of P-wave displacement increased linearly,and the peak value of S-wave displacement was nonlinear.The research results laid a theoretical foundation for dynamic support design for roadways.展开更多
Response surface methodology was utilized to model and optimize the operational variables for defluoridation using an electrodialysis process as the treatment of secondary effluent of the graphite industry. Experiment...Response surface methodology was utilized to model and optimize the operational variables for defluoridation using an electrodialysis process as the treatment of secondary effluent of the graphite industry. Experiments were conducted using a Box-Behnken surface statistical design in order to evaluate the effects and the interaction of the influential variables including the operational voltage, initial fluoride concentration and flow rate. The regression models for defluoridation and energy consumption responses were statistically validated using analysis of variance (ANOVA);high coefficient of determination values (R^2 = 0.9772 and R^2 = 0.9814;respectively) were obtained. The quadratic model exhibited high reproducibility and a good fit of the experimental data. The optimum values of the initial fluoride concentration, voltage and flow rate were found to be 13.9 mg/L, 13.4 V, 102.5 L/h, respectively. A fluoride removal efficiency of 99.69% was observed under optimum conditions for the treatment of the secondary effluent of the graphite industry.展开更多
基金supports for this work,provided by the Natural Science Foundation of Anhui Province(No.1908085QE187,1808085ME161)the Open Research Program of Key Laboratory of Safety and High-efficiency Coal Mining(No.JYBSYS2019202)the Open Research Program of State Key Laboratory Cultivation Base for Gas Geology and Gas Control(No.WS2019B09)are gratefully acknowledged.
文摘A comprehensive understanding of the failure behavior and mechanism of coal is a prerequisite for dealing with dynamic problems in mining space.In this study,the failure behavior and mechanism of coal under uniaxial dynamic compressive loads were experimentally and numerically investigated.The experiments were conducted using a split Hopkinson pressure bar(SHPB)system.The results indicated that the typical failure of coal is lateral and axial at lower loading rates and totally smashed at higher loading rates.The further fractography analysis of lateral and axial fracture fragments indicated that the coal failure under dynamic compressive load is caused by tensile brittle fracture.In addition,the typical failure modes of coal under dynamic load were numerically reproduced.The numerical results indicated that the axial fracture is caused directly by the incident compressive stress wave and the lateral fracture is caused by the tensile stress wave reflected from the interface between coal specimen and transmitted bar.Potential application was further conducted to interpret dynamic problems in underground coal mine and it manifested that the lateral and axial fractures of coal constitute the parallel cracks in the coal mass under roof fall and blasting in mining space.
基金funded by the National Natural Science Foundation of China(52204197)the National Natural Science Foundation of China(52104175)+1 种基金the China Postdoctoral Science Foundation(2025T180498,2022M712935)the Open Subjects of Xinjiang Key Laboratory of Green Mining of Coal Resources,Ministry of Education,China(KLXGY-KB2425).
文摘Accurately revealing the spatial distribution law of seismic displacement is signifcance for revealing the mechanism of dynamic load induced rockburst and guiding the dynamic support of roadway.This paper established the function of seismic displacement based on radiation energy,and compared the infuences of fracture type,radiation energy,shear strength,fracture velocity and medium density on the seismic displacement.The results showed that the displacement amplitudes of surrounding rock caused by P-wave,SH-wave and SV-wave increased with the rising of radiation energy,and the rate of displacement amplitude also accelerated.The displacement amplitudes of seismic wave associated with tensile fractures are signifcantly higher than that with shear fractures.The spatial displacement amplitude of S-wave was signifcantly higher than that of P-wave by one order of magnitude.The peak value of P-wave displacement of shear fracture was concentrated in two planes at 45°angle to the fracture surface.For SH-wave and SV-wave components,peak values were mainly observed on the fracture surface and its orthogonal plane.The P-wave displacement on the orthogonal plane to the fracture movement was zero,the displacement feld of SV-wave was distributed in four quadrants,and the displacement feld of SH-wave was symmetrical.The higher the value of medium attribute,the more signifcant the damage efect of coal-rock seismic wave weakening,and the infuence on the S-wave is greater than that of the P-wave.The displacement amplitude caused by seismic wave gradually increased with the rising of fracture velocity of coal-rock mass.The peak value of P-wave displacement increased linearly,and the peak value of S-wave displacement was nonlinear.The research results laid a theoretical foundation for dynamic support design for roadways.
基金financially supported by the Key Research Project of Shandong Province (No. 2017CXGC1004)the National Natural Science Foundation of China (Grant No. 21878178)+1 种基金the Shandong Science and Technology Development Plan (No. 2018GGX107001)the Young Taishan Scholars Program of Shandong Province.
文摘Response surface methodology was utilized to model and optimize the operational variables for defluoridation using an electrodialysis process as the treatment of secondary effluent of the graphite industry. Experiments were conducted using a Box-Behnken surface statistical design in order to evaluate the effects and the interaction of the influential variables including the operational voltage, initial fluoride concentration and flow rate. The regression models for defluoridation and energy consumption responses were statistically validated using analysis of variance (ANOVA);high coefficient of determination values (R^2 = 0.9772 and R^2 = 0.9814;respectively) were obtained. The quadratic model exhibited high reproducibility and a good fit of the experimental data. The optimum values of the initial fluoride concentration, voltage and flow rate were found to be 13.9 mg/L, 13.4 V, 102.5 L/h, respectively. A fluoride removal efficiency of 99.69% was observed under optimum conditions for the treatment of the secondary effluent of the graphite industry.
