Prediction of the soil saturated hydraulic conductivity in a mining area based on CT scanning technology

Abstract

In an open-cast mining area, large-scale machinery compaction causes severe soil degradation. Exploring the soil hydraulic characteristics at different bulk densities is of tremendous significance for soil restoration and soil hydrological balance in the reclamation area of the destructed land. Saturated hydraulic conductivity (Ks) is one of the important parameters to characterize soil infiltration capacity. The soil compaction in the mining area significantly affects soil saturated hydraulic conductivity, and its field measurement is very difficult due to the severe soil compaction. Precise prediction of soil saturated hydraulic conductivity is a prerequisite for understanding water movement and solute transport processes. In this study, soil samples taken from the dump site of the Antaibao open-pit coal mine in the Pingshuo mining area of China were prepared in laboratory according to different bulk densities (1.25, 1.3, 1.35, 1.4, 1.45, 1.5, 1.55, 1.6, 1.65, 1.7, 1.75, and 1.8 g cm−3), and the soil saturated water conductivity was measured in laboratory using constant head method. Moreover, the CT scanning technology was used to obtain soil macropore structure, and the fractal dimension of soil macropores was calculated, and the soil saturated water conductivity was predicted based on the fractal dimension. The number of macropores and macroporosity decreased with the increase in the bulk density, and the soil compaction resulted in poor connectivity of the soil macropores. The trend of the soil saturated water conductivity predicted using the CT scanning technique was consistent with that of the measured values in the laboratory under different bulk densities. With the increase of bulk density, the difference between the predicted value and the measured value increased slightly. Overall, a good prediction effect was achieved (R2 > 0.84). The prediction of the soil hydraulic characteristics of compacted soil in mining area based on CT scanning technology was feasible, and it can be applied to the study of practical problems in soil science.