Researchers from the National Institute for Occupational Safety and Health(NIOSH)are developing a coal pillar rib rating(CPRR)technique to measure the integrity of coal ribs.The CPRR characterizes the rib composition ...Researchers from the National Institute for Occupational Safety and Health(NIOSH)are developing a coal pillar rib rating(CPRR)technique to measure the integrity of coal ribs.The CPRR characterizes the rib composition and evaluates its impact on the inherent stability of the coal ribs.The CPRR utilizes four parameters:rib homogeneity,bedding condition,face cleat orientation with respect to entry direction,and rib height.All these parameters are measurable in the field.A rib data collecting procedure and a simple sheet to calculate the CPRR were developed.The developed CPRR can be used as a rib quality mapping tool in underground coal mines and to determine the potential of local rib instabilities and support requirements associated with overburden depth.CPRR calculations were conducted for 22 surveyed solid coal ribs,mainly composed of coal units.Based on this study,the rib performance was classified into four categories.A preliminary minimum primary rib support density(PRSD)line was obtained from these surveyed cases.Two sample cases are presented that illustrate the data collection form and CPRR calculations.展开更多
The instability of coal ribs in underground mines continues to result in the injuries and fatalities of mine workers.The proper esti-mation and evaluation of primary and secondary support for coal ribs is still a chal...The instability of coal ribs in underground mines continues to result in the injuries and fatalities of mine workers.The proper esti-mation and evaluation of primary and secondary support for coal ribs is still a challenging problem in the field of ground control science and requires further research and study.Although mining operations have various support design criteria and support methodologies for strata control,most rib support designs are still based on experience and local practices.This review study is intended to summarize the currently applied practices for rib support and control in various countries and mining conditions.Firstly,critical parameters that con-trol the amount and type of required rib support are considered and evaluated.The study revealed that among these parameters that control the stability of coal ribs,mining depth,rib height,cleat orientation/condition,and coal strength are the most significant param-eters.Secondly,current rib support application methods were also summarized.Similar to rock mass classification systems,some studies proposed a rib control rating system for practical estimation of the current rib condition and to estimate primary support requirements.These studies are classified and summarized into two groups(categorical and empirical)based on the required inputs and methodologies.Empirically based coal rib rating systems were closely examined,and the usefulness and intuitive aspects of each rating system were com-pared.This comprehensive literature review demonstrates that the Australian rating system,Analysis and Design of Rib Support(ADRS),and the new U.S.rating system,Coal Pillar Rib Rating(CPRR),are highly applicable for their regions.展开更多
文摘Researchers from the National Institute for Occupational Safety and Health(NIOSH)are developing a coal pillar rib rating(CPRR)technique to measure the integrity of coal ribs.The CPRR characterizes the rib composition and evaluates its impact on the inherent stability of the coal ribs.The CPRR utilizes four parameters:rib homogeneity,bedding condition,face cleat orientation with respect to entry direction,and rib height.All these parameters are measurable in the field.A rib data collecting procedure and a simple sheet to calculate the CPRR were developed.The developed CPRR can be used as a rib quality mapping tool in underground coal mines and to determine the potential of local rib instabilities and support requirements associated with overburden depth.CPRR calculations were conducted for 22 surveyed solid coal ribs,mainly composed of coal units.Based on this study,the rib performance was classified into four categories.A preliminary minimum primary rib support density(PRSD)line was obtained from these surveyed cases.Two sample cases are presented that illustrate the data collection form and CPRR calculations.
文摘The instability of coal ribs in underground mines continues to result in the injuries and fatalities of mine workers.The proper esti-mation and evaluation of primary and secondary support for coal ribs is still a challenging problem in the field of ground control science and requires further research and study.Although mining operations have various support design criteria and support methodologies for strata control,most rib support designs are still based on experience and local practices.This review study is intended to summarize the currently applied practices for rib support and control in various countries and mining conditions.Firstly,critical parameters that con-trol the amount and type of required rib support are considered and evaluated.The study revealed that among these parameters that control the stability of coal ribs,mining depth,rib height,cleat orientation/condition,and coal strength are the most significant param-eters.Secondly,current rib support application methods were also summarized.Similar to rock mass classification systems,some studies proposed a rib control rating system for practical estimation of the current rib condition and to estimate primary support requirements.These studies are classified and summarized into two groups(categorical and empirical)based on the required inputs and methodologies.Empirically based coal rib rating systems were closely examined,and the usefulness and intuitive aspects of each rating system were com-pared.This comprehensive literature review demonstrates that the Australian rating system,Analysis and Design of Rib Support(ADRS),and the new U.S.rating system,Coal Pillar Rib Rating(CPRR),are highly applicable for their regions.
