Effects of coal gangue-based porous materials on water movement in reclaimed substrates of mining areas

To address the challenge of topsoil scarcity during mine reclamation and to evaluate the feasibility of coal gangue -based porous material as a soil reconstruction medium,one-dimensional vertical soil column experiments were conducted to systematically investigate the effects of different incorporation rates (10%-30%) of the porous material on water infiltration and evaporation in a reclaimed substrate. The results showed that the porous material accelerated wetting front migration rate and increased cumulative infiltration,with the wetting front migration distance consistently exceeding that of the control group. The cumulative infiltration exhibited an initial increase followed by a decrease with increasing incorporation rate,reaching a maximum at 25%. The relationships of wetting front migration distance and cumulative infiltration with infiltration time were well described by a power function and the Kostiakov model,respectively. During evaporation,the material promoted evaporation at the mid-stage but demonstrated moisture retention at low incorporation rates at the later stage. Pot experiments further verified that under water stress, the material enhanced chlorophyll content in ryegrass, reduced soil compaction, and improved plant drought resistance. Environmental safety assessment indicated that the heavy metal content and leaching toxicity of the material were below the relevant national standard limits. Comprehensive analysis suggests that the coal gangue-based porous material achieves optimal water retention performance at an incorporation rate of 25%,demonstrating considerable potential for application in the ecological restoration of mining areas. The findings clarify the mechanism by which the porous material influences water movement and reveal the structure-function relationship between soil pore characteristics and hydrological processes,providing a scientific basis for water conservation and reclamation practices in mining regions.