基于CT扫描的煤矿排土场土壤孔隙三维多重分形特征

土壤孔隙对水分、养分的运移起着重要作用,重构土壤孔隙状况反映着复垦土壤质量的高低。本研究基于Math Works Matlab(2009a)平台,在对土壤孔隙CT扫描图片三维重建的基础上,运用多重分形理论对安太堡露天煤矿不同复垦年限排土场重构土壤(23年、20年、0年)以及原地貌土壤进行三维多重分形定量表征,以探讨重构土壤孔隙空间分布规律。结果表明:重构土壤孔隙三维结构具有多重分形特征,信息熵维D1、广义维数谱曲线弯曲程度△D、多重分形谱谱宽△α随着复垦年限逐渐增大,土壤孔隙状况得到改善,土壤孔隙分布越趋于复杂,变异程度较高;重构土壤及原地貌土壤孔隙三维分布多重分形谱函数△f0,呈左钩状,大概率孔隙占主要地位,孔隙分布不均匀。多重分形参数D1、D0-D1、△D、△α、△f间具有较好的相关性,从不同角度上反映了土壤孔隙三维分布的非均质性。

Three-dimensional Multi-fractal Characteristics of Reconstruction Soil Pore at Opencast Coal Mine Dump based on CT Scanning

Soil pore structure plays an important role in controlling physical and biological processes,such as nutrient cycling,water storage,gas exchange and mass migrating.The pore of reconstruction soil reflects the quality of reclaimed soil.In this paper,based on the three-dimensional reconstruction of soil pore by Matlab with CT scanning pictures,spatial distributionof soil pore was characterized bythree-dimensionalmuhi-fractal theoryafterreconstruction soil for 23 years,20 years,0 years at Antaibao opencast coal mine.Further,effects of dumping and reclamation on soil pore distribution were analyzed.The results indicated that the three-dimensional structure of the reconstructed soil pore had multi-fractal features.The normalized measures X (q,ε) versus measurement scale ε obeyed a power law scaling and the value of Dqfolloweda typical monotonically decreasing trend with increasing q values.The generalized dimension spectra of the original landform and soil reclamation for 23 years showed greater variation and the curves of unreclamed soil manifested gentler.All the values of D0 under different reclamation years were 1.0000.It indicated that all the boxes contained some pores,with not empty one.Parameter D0 cannot be used to reflect the characteristics of soil pore distributions.D1 was related to the entropy of the pore distribution system.It can be used to quantify the heterogeneity of pore distributions.The higher thevaluesof D1,the more heterogeneous and the wider the distributions of soil pore.The values of D1 had little difference,wandering at 0.9.They were ranked as Y ＞ Y23 ＞ Y20 ＞ Y0.△Dcan be used to reflect the variation degree of the local characteristics.The larger the values of △D,the stronger the degree of variation of the pore.The values of △D of Y,Y23,Y20 and Y0,respectively,were 0.9536-1.4183,0.7111-1.1567,0.8238-0.9320 and 0.5223-0.6531.The smaller the values of D0-D1,the lower the discrete degree of poredistribution at denser areas.The discrete degree ranked as:Y ＞ Y20 ＞ Y23 ＞ Y.△α is the width of the singularity spectra.It can portray the similarity or differences between the scaling properties of the measures and examine the local scaling property of the individual variables.The values of △α were ranked as Y ＞ Y23 ＞ Y20 ＞ Y0,similar to the values D1 and △D.The widths of spectrum △α were gradually increased withreclamation years,which indicated that the improvement of reclamation soil poremore variable.The f (α)-spectra among groups in this study showed distinctively different shape and symmetry.The shapes were left hook with △f ＞ 0.It showed that the high probability pores were dominated and the distributions of pore were nonuniform.There were better correlations among those multi-fractal parameters including D1,D0-D1,△D,△α and △f.They could quantify the heterogeneity characteristics of soil pore distribution at different levels.