Spraying characteristics of mining wet shotcrete

Taking the shotcrete in the coal mine as the background, the wet shotcreting technology is adopted to carry out the spraying characteristics test. Given the mix proportion of shotcrete in the coal mine, considering the influence of air pressure and sprayed distance, the spraying characteristics of shotcrete are studied, and the prediction model of mass flow rate is established. Based on the collected sprayed material in the process of shotcreting, the spatial distribution and composition of the sprayed materials are revealed. The research results show that the mass flow rate of shotcrete is more intensive in the central area around the axis of shotcrete. By comparing the mass distribution of shotcrete under different air pressures, it is found that excessive air pressure will cause in-place material collapsing during the placement process, resulting in a poor support effect. In addition, the relationship between spraying-up time and rebound rate, and the optimal initial spraying-up time are obtained. This paper provides theoretical and technical support for further study of spraying characteristics of wet shotcreting technology, which is helpful to promote the popularization and application of wet shotcrete.