Response of Soil Interlayer Structure of the Stacked Debris Body to Rainfall Infiltration

This study investigates the impact of adding soil interlayers into reconstructed soil-rock masses in abandoned mine areas on enhancing soil moisture conditions and facilitate the restoration of local ecological resources and environments. Employing a one-dimensional vertical constant head infiltration test, the study integrates soil layers into loose deposits. By adjusting the thickness and positioning of soil layers, control groups (CK₁-CK₄) are established, comprising pure soil and mixtures of 20%, 40%, and 60% gravel with air-dried soil. An orthogonal design is utilized to set up nine different treatment groups (T₁-T₉) to examine the effects of varying soil layer positions and thicknesses on moisture infiltration in loose deposits. The findings reveal that: (1) the presence of gravel impedes soil moisture infiltration, with average infiltration rates for CK₁-CK₄ being 0.44, 0.14, 0.11, and 0.10 mm·min^-1, respectively; (2) soil interlayers reduce infiltration time and enhance infiltration volume. Specifically, with a gravel content of 20%, the infiltration time for control group CK₂ is 1 to 2 times longer than that observed in treatment groups T₁, T₂, and T₃. When the gravel content increased to 60%, the infiltration time for treatment group T₇ is approximately three times that of T₉ and two times that of T₈. This suggests that thicker soil interlayers significantly improve moisture infiltration; (3) soil interlayers positioned in the middle layer exhibit a more pronounced effect in promoting moisture infiltration, with average infiltration times of 130, 117, and 160 minutes for the upper, middle, and lower layers, respectively; (4) both the Kostiakov infiltration equation and the Philip model are applicable for simulating such soil interlayers, with the Kostiakov equation demonstrating superior fitting performance, making it more suitable for such applications. These insights contribute to the understanding of moisture infiltration characteristics following the introduction of soil interlayers into reconstructed soil-rock masses, providing a theoretical foundation and scientific basis for ecological restoration and soil water conservation in mining areas.