A comprehensive monitoring program was conducted to measure the rock mass displacements, support response, and stress changes at a longwall tailgate entry in West Virginia.Monitoring was initiated a few days after dev...A comprehensive monitoring program was conducted to measure the rock mass displacements, support response, and stress changes at a longwall tailgate entry in West Virginia.Monitoring was initiated a few days after development of the gateroad entries and continued during passage of the longwall panels on both sides of the entry.Monitoring included overcore stress measurements of the initial stress within the rock mass, changes in cable bolt loading, standing support pressure, roof deformation, rib deformation,stress changes in the coal pillar, and changes in the full three-dimensional stress tensor within the rock mass at six locations around the monitoring site.During the passage of the first longwall, stress measurements in the rock and coal detected minor changes in loading while minor changes were detected in roof deformation.As a result of the relatively favorable stress and geological conditions, the support systems did not experience severe loading or rock deformation until the second panel approached within 10–15 m of the instrumented locations.After reaching the peak loading at about 50–75 mm of roof sag, the cable bolts started to unload, and load was transferred to the standing supports.The standing support system was able to maintain an adequate opening inby the shields to provide ventilation to the first crosscut inby the face, as designed.The results were used to calibrate modeled cable bolt response to field data, and to validate numerical modeling procedures that have been developed to evaluate entry support systems.It is concluded that the support system was more than adequate to control the roof of the tailgate up to the longwall face location.The monitoring results have provided valuable data for the development and validation of support design strategies for longwall tailgate entries.展开更多
As longwall tailgate support technologies continue to be developed and improved, strata worldwide has worked to design and manufacture a revised Propsetter to provide additional support capacity and enable application...As longwall tailgate support technologies continue to be developed and improved, strata worldwide has worked to design and manufacture a revised Propsetter to provide additional support capacity and enable applications at greater mine heights.The support is targeted for tailgate applications, however, it can also be utilized for roof support in various types of mining environments.This paper describes the design changes for enhancing the support capacity of the Propsetter to more closely align its performance with other support technologies currently being employed in longwall tailgates.Balancing changes to each design aspect of the Propsetter was key to successfully improving the roof support's load capacity while maintaining controlled deformation.Increasing the load capacity would allow a mine to improve support efficiency with a smaller, less intrusive support compared to support alternatives and reduce the cost per foot of supported entry.The target support capacity was 711–890 k N at 50 mm of deformation to more closely match the performance of competing tailgate supports such as the 610 mm-diameter CAN~.To achieve this goal, changes were made to all design aspects of the Propsetter: diameter, wedge cut depth and angle, pod size, and confinement rings.Test results from the NIOSH Mine Roof Simulator verified that these design changes were successful in increasing the capacity of the Propsetter to the 711–890 k N range at fifty mms of deformation.展开更多
Because of their technical advantages over ordinary metal springs, gas springs find usage in wide range of applications from furniture to aerospace industry as lifting, lowering or damping assists. Their integration t...Because of their technical advantages over ordinary metal springs, gas springs find usage in wide range of applications from furniture to aerospace industry as lifting, lowering or damping assists. Their integration to the tailgate operations in automotive industry is a challenging area, where not only the fundamental gas spring characteristics but also the mounting settings, working environment and tailgate body structure should be considered. The design and integration of these components will determine manual force exertion of operators thus the consideration of ergonomic characteristics of different populations is crucial. This paper introduces a recent visual academic software package, entitled TEM-SOFT, which is developed as a part of this research to perform ergo-mechanic simulations of tailgate operations with a fast, reliable and contemporary engineering approach and it is suitable for engineers and under-post graduate level students of mechanical and industrial engineering programs in the universities. The software developed and presented in this paper features all aspects of tailgate-gas spring operations considering the assembly scheme, tailgate mass center, gas spring type and working temperature in order to compute the required manual forces and the individual and combined impacts of acting parameters. Sufficient amount of scenarios were considered and the results were evaluated and discussed extensively. In addition to the other key findings, conducted research has shown that stronger gas springs, more effectively tend to move the critical tailgate position angle—where no operator force is needed to keep the tailgate opening—to the initial phases of the opening operation. A trade-off of this benefit is a superior initial manual force during closing.展开更多
文摘A comprehensive monitoring program was conducted to measure the rock mass displacements, support response, and stress changes at a longwall tailgate entry in West Virginia.Monitoring was initiated a few days after development of the gateroad entries and continued during passage of the longwall panels on both sides of the entry.Monitoring included overcore stress measurements of the initial stress within the rock mass, changes in cable bolt loading, standing support pressure, roof deformation, rib deformation,stress changes in the coal pillar, and changes in the full three-dimensional stress tensor within the rock mass at six locations around the monitoring site.During the passage of the first longwall, stress measurements in the rock and coal detected minor changes in loading while minor changes were detected in roof deformation.As a result of the relatively favorable stress and geological conditions, the support systems did not experience severe loading or rock deformation until the second panel approached within 10–15 m of the instrumented locations.After reaching the peak loading at about 50–75 mm of roof sag, the cable bolts started to unload, and load was transferred to the standing supports.The standing support system was able to maintain an adequate opening inby the shields to provide ventilation to the first crosscut inby the face, as designed.The results were used to calibrate modeled cable bolt response to field data, and to validate numerical modeling procedures that have been developed to evaluate entry support systems.It is concluded that the support system was more than adequate to control the roof of the tailgate up to the longwall face location.The monitoring results have provided valuable data for the development and validation of support design strategies for longwall tailgate entries.
文摘As longwall tailgate support technologies continue to be developed and improved, strata worldwide has worked to design and manufacture a revised Propsetter to provide additional support capacity and enable applications at greater mine heights.The support is targeted for tailgate applications, however, it can also be utilized for roof support in various types of mining environments.This paper describes the design changes for enhancing the support capacity of the Propsetter to more closely align its performance with other support technologies currently being employed in longwall tailgates.Balancing changes to each design aspect of the Propsetter was key to successfully improving the roof support's load capacity while maintaining controlled deformation.Increasing the load capacity would allow a mine to improve support efficiency with a smaller, less intrusive support compared to support alternatives and reduce the cost per foot of supported entry.The target support capacity was 711–890 k N at 50 mm of deformation to more closely match the performance of competing tailgate supports such as the 610 mm-diameter CAN~.To achieve this goal, changes were made to all design aspects of the Propsetter: diameter, wedge cut depth and angle, pod size, and confinement rings.Test results from the NIOSH Mine Roof Simulator verified that these design changes were successful in increasing the capacity of the Propsetter to the 711–890 k N range at fifty mms of deformation.
文摘Because of their technical advantages over ordinary metal springs, gas springs find usage in wide range of applications from furniture to aerospace industry as lifting, lowering or damping assists. Their integration to the tailgate operations in automotive industry is a challenging area, where not only the fundamental gas spring characteristics but also the mounting settings, working environment and tailgate body structure should be considered. The design and integration of these components will determine manual force exertion of operators thus the consideration of ergonomic characteristics of different populations is crucial. This paper introduces a recent visual academic software package, entitled TEM-SOFT, which is developed as a part of this research to perform ergo-mechanic simulations of tailgate operations with a fast, reliable and contemporary engineering approach and it is suitable for engineers and under-post graduate level students of mechanical and industrial engineering programs in the universities. The software developed and presented in this paper features all aspects of tailgate-gas spring operations considering the assembly scheme, tailgate mass center, gas spring type and working temperature in order to compute the required manual forces and the individual and combined impacts of acting parameters. Sufficient amount of scenarios were considered and the results were evaluated and discussed extensively. In addition to the other key findings, conducted research has shown that stronger gas springs, more effectively tend to move the critical tailgate position angle—where no operator force is needed to keep the tailgate opening—to the initial phases of the opening operation. A trade-off of this benefit is a superior initial manual force during closing.
