Study On Properties Of Soil Hydrology Under Different Reconstruction Patterns In Mining Area

The ecological environment problems in mining area such as vegetation deterioration,land degradation,water and soil erosion had caused by mining,and it is necessary to carry out ecological restoration in mining areas.The foundation of ecological restoration is soil,and the key is soil water.Soil water restricts the function and evolution of ecological system,and which has a bearing on the success of ecological restoration.Current research shows that coal gangue can be used as a filling matrix to reconstruct soil for ecological restoration in mining areas.However,the hydrological properties of reconstructed soil are greatly affected by factors such as the grain size and mixture ratio of coal gangue.Therefore,it is a key issue in ecological restoration in mining areas to understand and grasp the change rule of the hydrological properties of the soil under different reconstruction ways,so as to improve the soil moisture environment of reconstructed soil.In this study,the Gujiao mining area of Shanxi Province was taken as the research area.By measuring the soil water content under different reconstruction methods,it revealed the influence of reconstruction factors such as the mass fraction,grain size of coal gangue and soil bulk density on soil water content.The soil water characteristic curves under different coal gangue mass contents were drawn to explore the soil water holding capacity and available water content of reconstructed soil and their influencing factors.Finally,the soil water infiltration under different mass fractions of coal gangue and layered reconstruction methods were studied by water infiltration experiments.The results showed that the soil saturated water content,capillary moisture,and field capacity were negatively correlated with the three reconstruction factors,which were negative correlation with the coal gangue mass content was the most significant.The partial correlation coefficients between saturated water content,capillary moisture,field capacity and the mass fraction of coal gangue are-0.935,-0.953 and-0.909,respectively,and the mass fraction of coal gangue has the greatest impact on saturated water content,capillary moisture and field capacity of the soil.When the bulk density of the newly reconstructed soil is 1.3 g/cm~3 and the grain size of coal gangue is 0-2 mm,saturated water content,capillary moisture and field capacity of the soil are higher than those under other bulk densities and grain sizes,so the coal gangue with the grain size of 0-2 mm is chosen and the bulk density of the newly reconstructed soil is set as 1.3 g/cm~3.When bulk density of reconstructed soil and the grain size of coal gangue are constant,water-holding capacity of the soil gradually diminishes with the increase of the mass fraction of coal gangue,and it reaches the highest when the mass fraction of coal gangue is 10%.With the increase of the mass fraction of coal gangue,both available water content and difficult available water content of the soil show a downward trend,and when the mass fraction of coal gangue increases from 10% to 50%,available water content of the reconstructed soil decreases from 21.29% to 14.74%,and difficult available water content from 10.49% to 6.3%.The mass fraction of coal gangue is positively correlated with the soil water infiltration rate(y = 0.0116x+1.0299,R~2=0.982),and when the mass fraction of coal gangue is 50%,the water infiltration rate is the fastest.When the content of coal gangue is relatively high in the reconstructed soil,the use of hierarchical reconstruction way can effectively reduce infiltration and improve water-holding capacity of the soil.