Multi-fractal Characteristics Of Three-dimensional Distribution Of Reconstructed Soil Pores At Opencast Coal Mine Dump In Loess Area Based On High-precision CT Scanning

Soil pore plays an important role in migrating water and nutrient, the pore of reconstruction soil reflects the quality of reclaimed soil. In this paper, reconstruction soil of different reclamation years of Antaibao opencast coal mine including 23 years, 20 years, 0 years and the soil of original landform were chosen to be scanned to obtain the information of soil pore. Soil pore distribution of three-dimensional was reconstructed by matlab platform, then searching the number of soil pore groups and the volume of each group, the soil porosity was also calculated. Then soil pore space distribution of different reclamation years were characterized by three-dimensional multi-fractal theory. Further, effects of dumping and reclamation on soil pore distribution were analyzed. The results indicated that the following conclusions:(1) CT scanning can obtain the undestroyed information of soil pore. 3D distribution of soil pore can be realized by 3D reconstruction, and then the number and the volume of soil pore groups can be searched. It made the study of the soil pore be simpler.(2) The porosity and connectivity of reconstruction soil had been significantly improved as reclamation years increasing. The condition of reclaimed soil pore of 23 years was the best, the second was the 20 years soil, and the connectivity of unreclaimed soil pore was the worst as compacted by the large mechanism.(3) The three-dimensional structure of the reconstructed soil pore had multi-fractal features. The value of D1 and △D of 23 years reclaimed soil pore were largest, closing to the original landform soil, it showed a stronger degree of variation in soil pore distributions. The lowest one was the unreclaimed soil pore, the soil condition was poor.(4) The shapes in this study were left hook, the high probability pore was dominating and the distribution of pore was nonuniform. The width of multi-fractal spectrum △α was gradually increasing with increasing years of reclamation. The condition of reclamation soil pore had been improved, becoming more complex and more variable.(5) It had a better correlation among those multi-fractal parameters D1、D0-D1、△D、△α、and △f, they can reflect the heterogeneity characteristics of soil pore distribution in different levels.This study can provide guidance and basis for the reconstruction work in opencast coal mine dump in loess area.