Study On Soil Wind Erosion In Open-pit Coal Mines Based On Wind Tunnel Experiments

Soil wind erosion is the main cause of land desertification in arid and semi-arid areas.Due to the effect of climate change and human activities,soil wind erosion in China shows a trend of overall decrease and local deterioration in arid areas.Zhun Dong coalfield is the largest integrated coalfield in China.Human activities such as coal mining,transportation and loading and unloading will cause severe disturbance to the surrounding surface soil,thus aggravating the degree of soil wind erosion,at present,however,there is a lack of quantitative research on the influence of open-pit coal mining on soil erodibility.Therefore,in this paper,the scope of 727.87km~2in Hong Shaquan coal mine and its surrounding areas in Zhun Dong mining area is taken as the research area.One sampling point not affected by coal dust is selected for sampling.22 sampling points of 7 types of land,including bare land,sandy land,grassland,salinized and alkaline land,bare rock and gravel land,coal heap yard and soil dump yard in the mining area are selected for undisturbed soil sampling.The effects of soil moisture content,pulverized coal content,crust area and particle size on soil wind erosion were investigated by wind tunnel test and wind erosion sensor,and the sediment transport rate of different land types and the total sediment transport rate of the research area were estimated.The conclusions are as follows:(1)the sediment transport rate and the wind-sand flow height decreases with the increase of water content,and the wind speed of 14m/s makes soil particles jump.The amount and energy of particle collision decrease with the increase of water content.The wind speed of the first particle collision increases with the water content.(2)The results of sediment transport rate of coal powder in soil follow the rule of5%>10%>20%>40%>0%.The maximum sand flow height was obtained by adding pulverized coal.With the increase of the height,the collection amount of wind-sand flow decreases gradually,and the wind speed of 14m/s causes the saltation of soil particles.The results of particle collision number and energy in the experimental group of pulverized coal content followed the rule of 5%>10%>20%>0%>40%.The wind speed of the first particle collision increases with the increase of pulverized coal content.(3)Soil crusting rate increased and sediment transport rate decreased significantly.The wind speed of 14m/s can cause soil saltation,and the soil crust rate up to 50%can significantly reduce the height of wind sand flow.The number and energy of particle collision decrease with the increase of crust rate.The wind speed of the first particle collision increases with the increase of the crust rate.The sediment transport rate of the experimental group with uniform crust distribution was lower than that of the experimental group with a whole crust.(4)The sediment transport rate showed a trend of increasing first and then decreasing with the decrease of soil particle size.The experimental group of 0.125-0.5mm experienced saltation at the wind speed of 8m/s.Soil particles larger than 0.5mm almost do not collide,and the number and energy of soil particle collisions of 0.125-0.5mm are the highest,and the wind speed decreases first and then increases with the decrease of particle size in the first particle collision.(5)The order of soil erodibility of different soil types in the study area is as follows:sand>grassland>coal pile yard>bare field>drainage field>bare rock gravel field>saline-alkali land;The order of sediment transport rates of different land types in the study area is as follows:sand>grassland>bare land>bare rock gravel land>coal pile>soil dump>saline-alkali land;Under the wind speed of 10,12,14 and 16m/s,the total sediment transport rate of the study area was 25.97×104t/h,98.35×104t/h,271.38×104t/h,and 628.91×104t/h,respectively.Soil moisture content and soil particle size are the natural factors affecting wind erosion.Comprehensive the above conclusion,each influence factor has different effects on soil wind erosion,from the experiment of total sediment transport rate,the influence of four factors on wind erosion effect is shown as:soil particles>soil crust>moisture content>the content of pulverized coal,and various sample points in the study area of wind erosion and sediment transport rate is the result of joint action by multiple factors.