Spatial Distribution Law And Its Prediction Of The Inversion Layer In Deep Open-Pit Mine

Thermal inversion layer is a special atmospheric structure,which is resulted from the particular terrain structure and the solar radiation inside the stope.The inversion layer will hinder the convection of the air inside and outside the mine,so that the dust stays in the stope for a long time,causing huge pollution,and threatening personnel health and production safety.In this thesis,a deep open-pit mine is taken as the research object,and the research on the spatial distribution law and its prediction of the inversion layer in the deep open-pit mine under thermal action is studied by the combination of field measurement,theoretical analysis and numerical simulation.Field observations of the rock wall temperature and internal air temperature of the experimental mines in winter and spring were carried out by fixed-point observation and balloon sounding.The observation results show that the inversion temperature is more likely to occur in winter than in spring;the proportion of inversion layer with total thickness of inversion layer of no more than 50 m in the mining area is above 90%.The proportion of intensity less than 1?/100 m at 2 to 8 o'clock reaches up to 49.9%.The closed circle(+80 m above sea level)has a stable inversion layer at 2 to 8 o'clock,affecting the air convection outside the mine.Based on the principle of heat transfer,combined with field experiments,as well as taking into account the effects of heat radiation,heat convection and heat transfer,a theoretical model of the wall temperature variation in four typical directions of a deep open-pit mine is established,which is consistent with the experimental results.Using the digital elevation model(DEM)and considering the influence of topographic factors(slope direction,slope degree,and topography shielding)on deep open-pit mines,ArcGIS software is used to simulate the direct solar radiation time,the total solar radiation,the direct solar radiation and the solar scattering radiation in the deep open-pit mines for different seasons.Using the theory of atmospheric thermodynamics and the theory of gas-solid heat transfer,the theoretical model of the formation of the inversion layer of the deep open-pit mine and the basic equations of the lower atmosphere are established.Using the methods of field experiment and numerical simulation,the probability and intensity distribution of the inversion layer in the deep open-pit mine are studied in depth,and the relationship between the occurrence probability of the inversion layer and the average temperature as well as the adjacent average temperature difference in different height sections are analyzed.Finally,we construct a prediction model for the spatial distribution of the inversion layer.The research results in this thesis can not only be used to guide enterprises to arrange production reasonably and ensure the working environment in the stope,but also be used to supplement and improve the ventilation theory for open-pit mine and hence supply technical parameters for pollution prediction in open-pit mine stope.