Abstract:

The influence of soil and gravel on the infiltration and sediment yield on engineering spoil heaps was investigated via artificial simulated rainfall experiments. Three soil types (sand, loam, and clay) and gravel mass fractions (10%, 20%, and 30%, with bare slope as control) were evaluated under three rainfall intensities (1.0, 1.5, and 2.0 mm/min). The findings are summarized as follows: 1) sandy soils exhibited a continuous decrease in infiltration rate, whereas loam and clay showed stable infiltration at 6 min and 3-18 min, respectively. Gravel inhibited the infiltration of sandy soils but promoted it in clay soils. The initial and stable infiltration rates of loam increased with higher gravel mass fraction. 2) The average infiltration rate of sandy soil was 0.88-2.40 times and 1.04-2.18 times those of loam and clay, respectively. The Horton infiltration model effectively predicted the infiltration rates of loam and clay during rainfall, with errors ranging from 0.61% to 6.82%. 3) Erosion in sandy soils occurred throughout the entire rainfall process, becoming more severe in the later stages. In contrast, initial erosion in loam and clay was significantly greater than in the later stages. The average erosion rate of sandy soil was 4.74 times and 2.84 times those of loam and clay, respectively. 4) Gravel significantly inhibited erosion in sandy soil and loam at rainfall intensities of 1.5 and 2.0 mm/min, but increased erosion in sandy soil and clay at 1.0 mm/min. These results provide data foundation for developing soil erosion models for engineering spoil heaps, offering both theoretical and practical values.

Key words: spoil heaps, soil texture, mass fraction of gravel, rainfall simulation, infiltration, sediment yield