Study On The Characteristics Of Soil Preferential Flow In The Shenfu Dongsheng Coal Mining Subsidence Area

In recent decades,the demand for energy is increasing with the rapid development of industrial level.In particular,the mining of coal energy is increasing,resulting in a series of geological disasters and secondary disasters.The sharp decrease of surface runoff,large-scale surface subsidence and soil degradation have become a serious problem that threaten the production,life and social development of the mining area.Preferential flow is a common form of soil water movement,and it can make the water and solutes reach to the deep soil through preferential paths quickly.It has great influence on the production of surface runoff,soil erosion and the reserves of deep groundwater,which plays an important role in the hydrological process of the basin.Shigetai Coal Mine is one of Shenfu Dongsheng coal base.The cracks in the subsidence area are widely distributed,and the phenomenon of priority flow is common.Therefore,Shigetai Coal Mining Subsidence Area is taken as the research object.Through the field dyeing tracer experiment and the indoor water penetration experiment,the characteristics of the soil preferential flow morphological and types,the macropores quantity characteristics and the preferential flow path are analyzed by using software of Photoshop CS6,ArcGIS10.2 and SPSS.The characteristics of the soil preferential flow in the coal mining collapse area are systematically revealed.The following conclusions are drawn:(1)The characteristics of soil macropores in coal mining subsidence area: on the whole,the pore area of experimental area is between 0.3-1.3mm,and the pore size of soil is mainly distributed between 0.5-1.0mm.In test point 1,the distribution of soil pore is wide,which is 0.3mm-1.4mm,and the distribution of soil pore range is narrow in test point 2,which is 0.3-1.1cm.(2)Morphological characteristics of preferential flow in coal mining subsidence area: on the experimental section,the area of soil staining decreases with the increase of depth,and the location of dyeing area has certain continuity,because the distribution of pore structure and its priority path has continuity.With the increase of soil depth,the spatial variation coefficient of soil dyeing area in coal mining subsidence area increased with the increase of soil depth.With the increase of depth,the number of wide paths decreased and the number of small paths increased gradually at the two test points in the study area.(3)The characteristics of soil preferential flow type in coal mining subsidence area: The development of preferential flow is extremely unstable.The overall trend presents "homogeneous matrix flow?Heterogeneous matrix flow and fingering?Macropore flow with high interaction".Through the analysis of the type of soil priority flow in the coal mining subsidence area,it is concluded that the main soil flow is mainly soil Macropore flow in this study area.(4)Soil preferential flow characteristics of soil in coal mining subsidence area: Nonequilibrium characteristics of soil water infiltration in the study area Soil water infiltration and outflow rate in the test area,the steady rate of infiltration and outflow of the soil layer with preferential flow is greater than that of the soil layer that occurs in the matrix flow.The soil moisture characteristic curves of different depths have certain similarity and regularity,and the seepage flow and the percolation time have a certain logarithmic relationship.