The complex coal seam structure and hard roof at the Muchengjian Mine were studied, and the equivalent tensile strength of the roof was determined by a retrospective analysis of similar roof cave-ins. The prop spacing or number of hydraulic props required per unit area were obtained by analyzing the roof caving span and thickness. The early warning threshold bedding vertical separation velocity for hard roof caving at the Muchengjian Coal Mine was determined to be about 14 mm/day, and the newly invented ''bedding separation remote monitoring system'' (BSRMS) was used for the first time for early warning of a roof fall. A total of 48 trials of early warning roof weighting were performed at the Muchengjian Mine. It was found that not only were all the early warnings accurate, but the support system was also safe and reliable.Résumé : La structure complexe des couches de charbon et du toit à la mine Muchengjian a été étudiée. La résistance en tension équivalente du toit a été déterminée à partir d'une analyse rétrospective d'effondrements de toits similaires. L'espacement ou le nombre de supports hydrauliques nécessaires par unité de surface a été obtenu par l'analyse de l'intervalle et de l'épaisseur d'effondrements de toits. Le seuil d'alerte précoce de la vitesse de séparation verticale de la stratification pour les effondrements de toits à la mine de charbon Muchengjian a été instauré à 14 mm/jour. Le système de surveillance à distance de la séparation des strates récemment inventé a été utilisé pour la première fois pour des alertes précoces d'effondrement du toit. Au total, 48 pratiques d'alertes précoces de chargement du toit ont été réalisées. Il a été déterminé que non seulement les alertes précoces étaient appropriées, mais le système de support était sécuritaire et fiable.
There are abundant water resources in Tibet plateau area. With the increasing demand for electric power, it is necessary to build hydropower stations and test bench in Tibet Plateau area. The low air pressure has an influence on the flow in the hydraulic turbine. Therefore, a hydraulic turbine test bench is designed and built in the Tibet Plateau for low pressure hydraulic turbine experiment. The laboratory building is a three-storey structure with one distribution room and two control rooms. The civil structure is designed according to the layout of two test bench. The built underground storage tank has an area of 300 m2, a 15-meter high water tower and a capacity of 50 m3, which can meet the requirements of simultaneous operation of the two test bench The maximum head of the main pump is 30 meters, the rated power of the main motor is 160 kW, and the rated power of the dynamometer is 110 kW, which can be operated in both positive and negative directions. Meanwhile, a set of measurement and control system software is designed to acquire experimental data. The test bench will meet the needs of experimental teaching and scientific research of hydraulic turbines in Plateau area, and meet the performance comparison and acceptance test of medium and small hydro-machinery.
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