Prediction Of Hydraulic Characteristics Of Soils With Different Bulk Density Based On CT Technique

The large-scale compaction resulted from heavy machinaries in the mining area caused serious soil degradation,compaction leads to the reorganization of pore arrangement in the soil,limits the movement of soil water and nutrients,and is easy to cause serious consequences such as soil erosion and ecological deterioration,which brings great difficulty to the land reclamation work in the mining area.Exploring the hydraulic characteristics of soils with different bulk densities is of great significance for the restoration and maintenance of soil hydrological balance in the reclamation area.At present,the hydraulic characteristics of compacted soil in mining areas have not been studied deeply and lack a theoretical basis.In this study,soil samples of different bulk densities(1.3,1.4,1.5,1.6,1.7,and 1.8 g·cm^-3)from the Antaibao open-pit coal mine dump in Pingshuo of China,were prepared in the laboratory.Some samples in the laboratory used centrifugal method and pressure head method to measure the soil water characteristic curve and saturated hydraulic conductivity,respectively;and the others samples were obtained by CT scanning and three-dimensional reconstruction of the soil structure to obtain the characteristics of soil macropore structure under different bulk density conditions,and the physical experience Arya-Paris model and fractal model were used to predict soil water characteristic curve and soil saturation hydraulic conductivity respectively.Based on this,the impact of soil compaction on the hydraulic characteristics of the mining area was analyzed,and the prediction results were compared with the laboratory measured values,discussed the feasibility of model prediction.The study found that CT scanning of soil samples through three-dimensional reconstruction of soil pores can visually observe the internal structure of soil pores.Compaction resulted in the reduction of the number and macroporosity of soil pores,reducing the connectivity between macropores.The prediction of the hydraulic characteristics of the soil in the mining area showed that the change trend of the soil water characteristic curve and the saturated hydraulic conductivity was consistent with the laboratory measurement results,both decreased with the increase of bulk density.The prediction accuracy decreased with the increase of the bulk density,but overall it has achieved a good prediction effect.（R²>0.84）,so it is feasible to predict the hydraulic characteristics of soils with different bulk density in the mining area based on CT scanning technology,and it can be used to study practical problems.The study revealed the mechanism of soil bulk density and hydraulic characteristics,and it can provide some theoretical basis and technical support for land reclamation management.