Rock mass is a fractured porous medium usually subjected to complex geostress and fluid pressure simultaneously.Moreover,the properties of rock mass change in time and space due to mining-induced fractures.Therefore,i...Rock mass is a fractured porous medium usually subjected to complex geostress and fluid pressure simultaneously.Moreover,the properties of rock mass change in time and space due to mining-induced fractures.Therefore,it is always challenging to accurately measure rock mass properties.In this study,a three-dimensional(3D)microseismic(MS)data-driven damage model for jointed rock mass under hydro-mechanical coupling conditions is proposed.It is a 3D finite element model that takes seepage,damage and stress field effects into account jointly.Multiple factors(i.e.joints,water and microseismicity)are used to optimize the rock mass mechanical parameters at different scales.The model is applied in Shirengou iron mine to study the damage evolution of rock mass and assess the crown pillar stability during the transition from open-pit to underground mining.It is found that the damage pattern is mostly controlled by the structure,water and rock mass parameters.The damage pattern is evidently different from the two-dimensional result and is more consistent with the field observations.This difference is caused by the MS-derived damage acting on the rock mass.MS data are responsible for gradually correcting the damage zone,changing the direction in which it expands,and promoting it to evolve close to reality.For the crown pillar,the proposed model yields a more trustworthy safety factor.In order to guarantee the stability of the pillar,it is suggested to take waterproof and reinforcement measures in areas with a high degree of damage.展开更多
The electric field intensity (EFI) is important characteristic quantity for evaluating the internal insulation state of cable joints. Based on finite element method, this paper proposes two EFI research methods, field...The electric field intensity (EFI) is important characteristic quantity for evaluating the internal insulation state of cable joints. Based on finite element method, this paper proposes two EFI research methods, field-circuit coupling method and equivalent circuit method. The average EFI of the inner surface of the outer semi-conducting shield can be calculated from the current in the measuring circuit. The relative error between these two methods is about 15%, which roughly proves the consistency of the two methods. Further practical application research enables online monitoring of cable joints.展开更多
Various defects exist in natural rock masses,withfilled joints being a vital factor complicating both the mechanical characteristics and seepage mechanisms of the rock mass.Filled jointed rocks usually show mechanical...Various defects exist in natural rock masses,withfilled joints being a vital factor complicating both the mechanical characteristics and seepage mechanisms of the rock mass.Filled jointed rocks usually show mechanical properties that are weaker than those of intact rocks but stronger than those of rocks with fractures.The shape of the rock,filling material,prefabricatedfissure geometry,fissure roughness,fissure inclination angle,and other factors mainly influence the mechanical and seepage properties.This paper systematically reviews the research progress andfindings onfilled rock joints,focusing on three key aspects:mechanical properties,seepage properties,andflow properties under mechanical response.First,the study emphasizes the effects of prefabricated defects(shape,size,filling material,inclination angle,and other factors)on the mechanical properties of the rock.The fracture extension behavior of rock masses is revealed by the stress state of rocks withfilled joints under uniaxial compression,using advanced auxiliary test techniques.Second,the seepage properties of rocks withfilled joints are discussed and summarized through theoretical analysis,experi-mental research,and numerical simulations,focusing on organizing the seepage equations of these rocks.The study also considers the form of failure under stress-seepage coupling for both fullyfilled and partiallyfilledfissured rocks.Finally,the limitations in the current research on the rock withfilled joints are pointed out.It is emphasized that the specimens should more closely resemble real conditions,the analysis of mechanical indexes should be multi-parameterized,the construction of the seepage model should be refined,and the engineering coupling application should be multi-field-multiphase.展开更多
基金We acknowledge the combined support from the National Natural Science Foundation of China(Grant Nos.52039007 and 42102325)Tiandi Science and Technology Co.,Ltd.(Grant No.2022-2-TD-MS012).
文摘Rock mass is a fractured porous medium usually subjected to complex geostress and fluid pressure simultaneously.Moreover,the properties of rock mass change in time and space due to mining-induced fractures.Therefore,it is always challenging to accurately measure rock mass properties.In this study,a three-dimensional(3D)microseismic(MS)data-driven damage model for jointed rock mass under hydro-mechanical coupling conditions is proposed.It is a 3D finite element model that takes seepage,damage and stress field effects into account jointly.Multiple factors(i.e.joints,water and microseismicity)are used to optimize the rock mass mechanical parameters at different scales.The model is applied in Shirengou iron mine to study the damage evolution of rock mass and assess the crown pillar stability during the transition from open-pit to underground mining.It is found that the damage pattern is mostly controlled by the structure,water and rock mass parameters.The damage pattern is evidently different from the two-dimensional result and is more consistent with the field observations.This difference is caused by the MS-derived damage acting on the rock mass.MS data are responsible for gradually correcting the damage zone,changing the direction in which it expands,and promoting it to evolve close to reality.For the crown pillar,the proposed model yields a more trustworthy safety factor.In order to guarantee the stability of the pillar,it is suggested to take waterproof and reinforcement measures in areas with a high degree of damage.
文摘The electric field intensity (EFI) is important characteristic quantity for evaluating the internal insulation state of cable joints. Based on finite element method, this paper proposes two EFI research methods, field-circuit coupling method and equivalent circuit method. The average EFI of the inner surface of the outer semi-conducting shield can be calculated from the current in the measuring circuit. The relative error between these two methods is about 15%, which roughly proves the consistency of the two methods. Further practical application research enables online monitoring of cable joints.
基金Postgraduate Research&Practice Innovation Program of Jiangsu Province for Funding support,Grant/Award Number:KYCX22_2843Postgraduate Research&Practice Innovation Program of Jiangsu Province,Grant/Award Number:2024XKT0628National Natural Science Foundation of China,Grant/Award Number:52034007。
文摘Various defects exist in natural rock masses,withfilled joints being a vital factor complicating both the mechanical characteristics and seepage mechanisms of the rock mass.Filled jointed rocks usually show mechanical properties that are weaker than those of intact rocks but stronger than those of rocks with fractures.The shape of the rock,filling material,prefabricatedfissure geometry,fissure roughness,fissure inclination angle,and other factors mainly influence the mechanical and seepage properties.This paper systematically reviews the research progress andfindings onfilled rock joints,focusing on three key aspects:mechanical properties,seepage properties,andflow properties under mechanical response.First,the study emphasizes the effects of prefabricated defects(shape,size,filling material,inclination angle,and other factors)on the mechanical properties of the rock.The fracture extension behavior of rock masses is revealed by the stress state of rocks withfilled joints under uniaxial compression,using advanced auxiliary test techniques.Second,the seepage properties of rocks withfilled joints are discussed and summarized through theoretical analysis,experi-mental research,and numerical simulations,focusing on organizing the seepage equations of these rocks.The study also considers the form of failure under stress-seepage coupling for both fullyfilled and partiallyfilledfissured rocks.Finally,the limitations in the current research on the rock withfilled joints are pointed out.It is emphasized that the specimens should more closely resemble real conditions,the analysis of mechanical indexes should be multi-parameterized,the construction of the seepage model should be refined,and the engineering coupling application should be multi-field-multiphase.
