In this research,the dynamics of wet spray nozzles with different geometries,used to accelerate shotcrete,are investigated on the basis of a suitable three-dimensional mathematical model and related numerical method.S...In this research,the dynamics of wet spray nozzles with different geometries,used to accelerate shotcrete,are investigated on the basis of a suitable three-dimensional mathematical model and related numerical method.Simulations have been conducted in the frame of the SIMPLEC algorithm.The k-εturbulence model has been used to account for turbulent effects.The study shows that when the angle of the convergent section is less than 3°,it has a scarce effect on the dynamics of the jet of shotcrete;with the increase of the convergence angle,the shotcrete jet velocity decreases and the nozzle wear increases;when this angle is greater than 6°,the concrete outlet jet velocity is very small and the nozzle can easily be blocked.Experimental results are in good agreement with the outcomes of the numerical simulations,which indicates that the used approach is reliable.展开更多
In this paper, the technical research on the application of stone chips in wet-mixed shotcrete is carried out. By comparing the consistency, initial setting time, final setting time, strength, rebound rate, project co...In this paper, the technical research on the application of stone chips in wet-mixed shotcrete is carried out. By comparing the consistency, initial setting time, final setting time, strength, rebound rate, project cost and other indicators of wet-mixed shotcrete with natural sand and stone chips, the technical and theoretical feasibility of stone chips based wet-mixed shotcrete is determined. Through indoor raw material quality analysis, mix proportion design and verification, and project site construction effect verification, the results are good. First, the fineness modulus and gradation range of raw materials of natural sand and stone chips are basically the same, the particle shape is different, and internal friction and bonding are good. Secondly, the mix proportion, sand ratio and water-binder ratio of natural sand and stone chip-based sprayed concrete are the same, and the mixing time of stone chip-based sprayed concrete needs to be prolonged by 15S. Thirdly, according to the characteristics of stone chip-based shotcrete, such as strong cohesive force and low rebound rate, the thickness of single shotcrete can reach 100mm for the vault and 120mm for the side wall, thus improving the working efficiency.展开更多
Based on the refractories research of Baosteel, the demands for refractories from the developing steel-making technology as high security, high efficiency, energy saving and environment .friendly are introduced.
基金financially supported by the Foundation of State Key Laboratory of Safety and Health for Metal Mines(2018-JSKSSYS-05).
文摘In this research,the dynamics of wet spray nozzles with different geometries,used to accelerate shotcrete,are investigated on the basis of a suitable three-dimensional mathematical model and related numerical method.Simulations have been conducted in the frame of the SIMPLEC algorithm.The k-εturbulence model has been used to account for turbulent effects.The study shows that when the angle of the convergent section is less than 3°,it has a scarce effect on the dynamics of the jet of shotcrete;with the increase of the convergence angle,the shotcrete jet velocity decreases and the nozzle wear increases;when this angle is greater than 6°,the concrete outlet jet velocity is very small and the nozzle can easily be blocked.Experimental results are in good agreement with the outcomes of the numerical simulations,which indicates that the used approach is reliable.
文摘In this paper, the technical research on the application of stone chips in wet-mixed shotcrete is carried out. By comparing the consistency, initial setting time, final setting time, strength, rebound rate, project cost and other indicators of wet-mixed shotcrete with natural sand and stone chips, the technical and theoretical feasibility of stone chips based wet-mixed shotcrete is determined. Through indoor raw material quality analysis, mix proportion design and verification, and project site construction effect verification, the results are good. First, the fineness modulus and gradation range of raw materials of natural sand and stone chips are basically the same, the particle shape is different, and internal friction and bonding are good. Secondly, the mix proportion, sand ratio and water-binder ratio of natural sand and stone chip-based sprayed concrete are the same, and the mixing time of stone chip-based sprayed concrete needs to be prolonged by 15S. Thirdly, according to the characteristics of stone chip-based shotcrete, such as strong cohesive force and low rebound rate, the thickness of single shotcrete can reach 100mm for the vault and 120mm for the side wall, thus improving the working efficiency.
文摘Based on the refractories research of Baosteel, the demands for refractories from the developing steel-making technology as high security, high efficiency, energy saving and environment .friendly are introduced.
