| There were many kinds of mineral resources in Taihang mountain areas of Hebei province, such as gold, coal, iron ore, limestone mine. The mining could bring huge economic benefits, but produce a large number of waste residues at the same time with unreasonable mining. Because the irregular slag stacking and the superposition effects of heavy rainfall, slag stacking areas often made environmental problems such as landslide and debris flow. Rainfall was the dominant factor in mine geology disaster. If we could collect rain, it could reduce or control the rain runoff, as not only prevented disaster, but also solved the problem of mountainous area with water. Therefore, the slag of limestone mine in Mancheng county of Baoding city in Hebei province was selected as the main object of study, we adopted the methods of combining laboratory test and field investigation to explore the rainfall infiltration features of mining waste residues with different type and grade of particles, and to solve the problem of water and rainfall disasters, promote the development of the mine ecological environment. The results showed that:(1)Limestone mineral powder type slag gave first place to the slag which size was2mm-7mm, account37.23%.Fine material was the most part of this type slag. Slag’s natural angle of repose was between30o to45o.With the increased of water content, its angle of repose increased gradually. When the rain led to slag’s moisture content was more than16%, slag from solid to fluid, then it could destabilize the slag’s heap.(2) The water capacity of slag was from19.18%to35.28%with the size increased. In natural soil, the water capacity of clay and silty clay were bigger, it was22.15%and18.85%, the water capacity of silt to gravelly soil was from11.86%increased to14.37%with the increased of size. Compared with slag, the water capacity of natural soil was smaller. Regardless the influence of soil’s permeability coefficient, if rainfall over the water capacity of soil, it form the rainfall runoff, lead to soil erosion. Compared with natural soil, the water capacity of slag was bigger, it was from9%to35%, water easy to downward migration. The water retaining capacity of natural soil was bigger, it was from1.37%to20.15%, it’s easy to keep water, it’s suitable for plant growth. Therefore, we can mix up slag and natural soil as the matrix in the vegetation restoration, not only slag get effective use, but also benefit to the ecological environment of mine.(3) The permeability coefficient of each particle size of slag was1.2-126.7m/d, and the permeability coefficient of undisturbed mineral of powder type slag was about100.4m/d. If the rainfall intensity is greater than100.4m/d, then the runoff come into being. In natural soil, clay’s permeability coefficient just was0.001m/d, only.Gravel soil’s permeability coefficient was larger,it was22m/d. It was smallest than slag, it related to the size of lump. Under the same rainfall intensity, the runoff is formed easily in the area of mine slope where only covering natural soil rainfall.(4) The infiltration coefficient of each particle size of slag was0.53to0.96, and the natural soil was0.28to0.77.Compared with the slag, it was smaller. The greater soil’s infiltration coefficient, the easier rain into soil, and its water content was greater. But the angle of repose experiment results showed that when the water content of soil is large enough, then destroy the stability of the soil.(5) There was a positive correlation coefficient and permeability coefficient of slag infiltration relationship, Built the infiltration coefficient and permeability coefficient of the regression equation was:y=0.05941n(x)+0.6357.And the relationship of natural soil’s infiltration coefficient and permeability coefficient was y=0.03521n(x)+0.6455. |
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