Research on typical soil physical properties in a mining area: Feasibility of three-dimensional ground penetrating radar detection

The mining and reclaiming techniques of open-pit coal mines will affect the physical properties of the soil and the growth of vegetation. The traditional method of obtaining soil physical properties is time-consuming and laborious, so developing a rapid and non-destructive method for detecting typical soil physical properties in mining areas is of great significance for reclamation work. To study the typical soil physical properties of the reclaimed land in the mining area, we took the dumping sites of the Antaibao Open-pit Mine of China Coal as the research object and obtained measured data through the Ground Penetrating Radar (GPR) detection method and the soil profile sampling method. Then, the image analysis method, statistical analysis method and comparative analysis method were used to analyze the spatial variability for the soil moisture content, the effective soil layer thickness and the soil gravel content in the reclamation area. The results support the following conclusions: (1) The typical soil physical properties, namely, the soil moisture content, the effective soil layer thickness and the soil gravel content, of the reclaimed land in the mining area vary spatially. (2) Locally strong and fluctuating strong reflections in the 3D GPR image indicate that the detected sample is partially rich in water, and the spatial variability in the sudden moisture content of the reclamation in the mining area can be analyzed. (3) A low-frequency signal with good continuity in the 3D GPR image indicates that there is soil stratification under the detected sample, and the depth of the low-frequency signal with good continuity in the 3D GPR image can be used to characterize the effective soil layer in the reclaimed area. (4) The soil gravel content of the reclaimed soil can be analyzed from the statistics of the number of isolated gravel signals in the 3D GPR image. The greater the number of isolated gravel signals is, the higher the soil gravel content is. These conclusions, from both horizontal and vertical perspectives, suggest that 3D GPR images can be used to determine the typical physical properties of soil in a reclaimed land. These results can provide technical support for the efficient reclamation of a mining area and related restoration work.