The deformation characteristics and thermal response of anchor rods are crucial for ensuring the stability and safety of surrounding rock support structures.However,existing research has predominantly concentrated on ...The deformation characteristics and thermal response of anchor rods are crucial for ensuring the stability and safety of surrounding rock support structures.However,existing research has predominantly concentrated on the mechanical performance of anchor rods,with limited attention to the coupled evolution of strain and temperature fields during tensile deformation.This knowledge gap hinders a comprehensive understanding of the synergistic mechanical-thermal response mechanisms in anchor rods under loading conditions.To address this limitation,the present study systematically investigated the evolution of strain and temperature fields,along with their correlation,during the test of micro-negative Poisson's ratio(NPR)and ordinary Poisson's ratio(PR)anchor rods.Digital image correlation(DIC)and infrared thermography(IRT)techniques were employed for this exploration.The uniaxial tensile tests were conducted at two different rates,and the ordinary PR anchor rod(Q235 anchor rod)was established as a control group for comparative analysis.The findings reveal that the micro-NPR anchor rod exhibit strain localization at multiple locations during the tensile process,whereas Q235 anchors show local strain concentration in only one region.The standard deviation evolution curves for both the strain and temperature field exhibit two distinct phases in the two anchor rods.The evolution patterns between these two types of curves are basically consistent.The two standard deviation curves for the micro-NPR anchor rod display a wavy increase in the second phase,while for the Q235 anchor rod,they increase steadily until the specimen is damaged.The correlation analysis reveals that the standard deviations of strain and temperature differences for both types of anchor rods are significantly correlated.These findings demonstrate the synergistic evolution mechanism of deformation and thermal response,providing a potential foundation for utilizing thermal monitoring to assess the stability of rock support structures.展开更多
A novel meta steel with negative Poisson’s ratio effect(termed as micro-NPR steel)is developed for rock support in deep underground engineering.It possesses high strength,high ductility,and high energy absorption cha...A novel meta steel with negative Poisson’s ratio effect(termed as micro-NPR steel)is developed for rock support in deep underground engineering.It possesses high strength,high ductility,and high energy absorption characteristics.In this paper,static tension and modified dynamic drop hammer tests are performed on this novel material to investigate its mechanical properties first.Then based on this material,a new generation of micro-NPR anchor cable is developed and applied in field tests subjected to blasting dynamic loads.The results of laboratory tests reveal that the ultimate elongation of micro-NPR steel under dynamic impacts is more than 30%and it is over 1.5 times that of Q235;the plastic and total energy absorption of micro-NPR are both significantly higher than that of Q235.Field test indicates the fine controlling effect of micro-NPR anchor cable on surrounding rock mass under dynamic loads.Axial force confirms that micro-NPR cables can distribute and absorb the dynamic energy uniformly around the supported rock when subjected to dynamic disturbance,avoiding local failure induced by excessive stress concentration.The excavation compensation principle and energy-absorbing characteristics are used to explain the support mechanisms.Thus,micro-NPR material and anchor cable can control and prevent dynamic disasters in deep underground engineering effectively.展开更多
基金supported by State Key Laboratory for Geomechanics and Deep Underground Engineering,China University of Mining&Technology,Beijing(Grant No.SKLGDUEK2120)。
文摘The deformation characteristics and thermal response of anchor rods are crucial for ensuring the stability and safety of surrounding rock support structures.However,existing research has predominantly concentrated on the mechanical performance of anchor rods,with limited attention to the coupled evolution of strain and temperature fields during tensile deformation.This knowledge gap hinders a comprehensive understanding of the synergistic mechanical-thermal response mechanisms in anchor rods under loading conditions.To address this limitation,the present study systematically investigated the evolution of strain and temperature fields,along with their correlation,during the test of micro-negative Poisson's ratio(NPR)and ordinary Poisson's ratio(PR)anchor rods.Digital image correlation(DIC)and infrared thermography(IRT)techniques were employed for this exploration.The uniaxial tensile tests were conducted at two different rates,and the ordinary PR anchor rod(Q235 anchor rod)was established as a control group for comparative analysis.The findings reveal that the micro-NPR anchor rod exhibit strain localization at multiple locations during the tensile process,whereas Q235 anchors show local strain concentration in only one region.The standard deviation evolution curves for both the strain and temperature field exhibit two distinct phases in the two anchor rods.The evolution patterns between these two types of curves are basically consistent.The two standard deviation curves for the micro-NPR anchor rod display a wavy increase in the second phase,while for the Q235 anchor rod,they increase steadily until the specimen is damaged.The correlation analysis reveals that the standard deviations of strain and temperature differences for both types of anchor rods are significantly correlated.These findings demonstrate the synergistic evolution mechanism of deformation and thermal response,providing a potential foundation for utilizing thermal monitoring to assess the stability of rock support structures.
基金supported by the National Natural Science Foundation of China(Grant No.41941018)the Foundation of State Key Laboratory for Geomechanics and Deep Underground Engineering(Grant No.SKLGDUEK 2217)the Collaborative Innovation Center for Prevention and Control of Mountain Geological Hazards of Zhejiang Province(Grant No.PCMGH-2022-03).
文摘A novel meta steel with negative Poisson’s ratio effect(termed as micro-NPR steel)is developed for rock support in deep underground engineering.It possesses high strength,high ductility,and high energy absorption characteristics.In this paper,static tension and modified dynamic drop hammer tests are performed on this novel material to investigate its mechanical properties first.Then based on this material,a new generation of micro-NPR anchor cable is developed and applied in field tests subjected to blasting dynamic loads.The results of laboratory tests reveal that the ultimate elongation of micro-NPR steel under dynamic impacts is more than 30%and it is over 1.5 times that of Q235;the plastic and total energy absorption of micro-NPR are both significantly higher than that of Q235.Field test indicates the fine controlling effect of micro-NPR anchor cable on surrounding rock mass under dynamic loads.Axial force confirms that micro-NPR cables can distribute and absorb the dynamic energy uniformly around the supported rock when subjected to dynamic disturbance,avoiding local failure induced by excessive stress concentration.The excavation compensation principle and energy-absorbing characteristics are used to explain the support mechanisms.Thus,micro-NPR material and anchor cable can control and prevent dynamic disasters in deep underground engineering effectively.
