Through cooperative research between the government,the private sector, mining companies and equipment manufacturers,considerable progress had been made during the last decade in studying the mechanics of strata failu...Through cooperative research between the government,the private sector, mining companies and equipment manufacturers,considerable progress had been made during the last decade in studying the mechanics of strata failure and acquiring the know- ledge needed to develop an integrated monitoring system for assessing local roof stability. Because of higher geotechnical risks in retreat mining operations,it was both important to develop panel layout designs that control convergence and stress and to monitor ground response during operations to verify designs and provide warning of impending stability problems.For detecting both localized roof stability problems and global overburden col- lapse mechanisms,the proposes an integrated panel-wide monitoring system which com- bines the capabilities of load rate monitoring of mobile roof supports (MRSs) with deforma- tion measurements using an extensive array of sensors located near the mining face and throughout the panel.Two monitoring methods for the detection of localized roof stability problems have been evaluated on the basis of mine measurements and numerical model- ing considerations.These are load rate monitoring of the hydraulic cylinders of mobile roof support (MRS) and re mote monitoring of roof movements.Analyses of field data in retreat sections show that roof instabilities are influenced by: (1) pillar failure,(2) pillar yielding,(3) mine seismicity (bumps),(4) geologic structures,and (5) panel layout designs and practice. Pillar yielding and unloading can be conveniently monitored by the load rate monitoring device,but to detect impending localized roof falls,additional ground deformation meas- urements are needed near the mining face.By increasing the number of deformation measurements in the entire panel,additional safeguards can be achieved for detecting overburden collapse mechanisms while continuously monitoring local roof stability close to the retreat line.展开更多
Nowadays,additive manufacturing,or 3D printing(3DP),though not a new technology in many industrial fields,is still relatively novel in mining engineering.This study explored the application of 3D metal printing,3D pol...Nowadays,additive manufacturing,or 3D printing(3DP),though not a new technology in many industrial fields,is still relatively novel in mining engineering.This study explored the application of 3D metal printing,3D polylactic acid/acrylonitrile butadiene styrene printing,and 3D concrete printing in coal mining.Some examples of physical models established via 3DP technologies were studied in detail,namely,3DP bolts,3DP steel ladder beams,3DP face plates,and 3DP metal arches,which were installed in scaled 3DP concrete prototype models of coal mine excavation.Through the comprehensive laboratory loading tests,the models could simulate the damage scenario highly similar to the real failures.The results show that the 3D printed physical models greatly improved the accuracy and reliability of experiments.On this basis,the conceptual design of a 3DP machine for physical models was proposed,which had the potential of resembling the strata deformation/collapse in natural scenarios.Through assessing the applicability of the additive manufacturing technology in mining engineering,this study aimed to further explore its potential applicability in other engineering contexts such as slope controlling,large underground engineering,and underground space stability.展开更多
基金National Institute of Occupational Safety and Health and Fletcher
文摘Through cooperative research between the government,the private sector, mining companies and equipment manufacturers,considerable progress had been made during the last decade in studying the mechanics of strata failure and acquiring the know- ledge needed to develop an integrated monitoring system for assessing local roof stability. Because of higher geotechnical risks in retreat mining operations,it was both important to develop panel layout designs that control convergence and stress and to monitor ground response during operations to verify designs and provide warning of impending stability problems.For detecting both localized roof stability problems and global overburden col- lapse mechanisms,the proposes an integrated panel-wide monitoring system which com- bines the capabilities of load rate monitoring of mobile roof supports (MRSs) with deforma- tion measurements using an extensive array of sensors located near the mining face and throughout the panel.Two monitoring methods for the detection of localized roof stability problems have been evaluated on the basis of mine measurements and numerical model- ing considerations.These are load rate monitoring of the hydraulic cylinders of mobile roof support (MRS) and re mote monitoring of roof movements.Analyses of field data in retreat sections show that roof instabilities are influenced by: (1) pillar failure,(2) pillar yielding,(3) mine seismicity (bumps),(4) geologic structures,and (5) panel layout designs and practice. Pillar yielding and unloading can be conveniently monitored by the load rate monitoring device,but to detect impending localized roof falls,additional ground deformation meas- urements are needed near the mining face.By increasing the number of deformation measurements in the entire panel,additional safeguards can be achieved for detecting overburden collapse mechanisms while continuously monitoring local roof stability close to the retreat line.
基金National Natural Science Foundation of China,Grant/Award Number:51804296China Scholarship Council Grant,Grant/Award Number:CSC#202006425019。
文摘Nowadays,additive manufacturing,or 3D printing(3DP),though not a new technology in many industrial fields,is still relatively novel in mining engineering.This study explored the application of 3D metal printing,3D polylactic acid/acrylonitrile butadiene styrene printing,and 3D concrete printing in coal mining.Some examples of physical models established via 3DP technologies were studied in detail,namely,3DP bolts,3DP steel ladder beams,3DP face plates,and 3DP metal arches,which were installed in scaled 3DP concrete prototype models of coal mine excavation.Through the comprehensive laboratory loading tests,the models could simulate the damage scenario highly similar to the real failures.The results show that the 3D printed physical models greatly improved the accuracy and reliability of experiments.On this basis,the conceptual design of a 3DP machine for physical models was proposed,which had the potential of resembling the strata deformation/collapse in natural scenarios.Through assessing the applicability of the additive manufacturing technology in mining engineering,this study aimed to further explore its potential applicability in other engineering contexts such as slope controlling,large underground engineering,and underground space stability.
