红壤区生态保护修复对于我国国土生态安全建设具有重要意义,针对喷混植生技术使用水泥作为固化剂导致的环境污染、降解难度大、植物生长受限等问题,以南方某输变电工程红壤边坡为对象,以海藻多糖为固化剂替代水泥,加入玉米纤维、保水剂和生态肥料以提高基材生态恢复性能,开展室内模拟降雨试验,分析不同基材对初始产流时间、产流产沙过程和水动力参数的影响,最终选出一组最优基材。结果表明:相较于裸坡,基材坡面的初始产流时间显著缩短;产流率显著增加,排水效益达16.35%~52.73%,产沙率显著降低,保土效益达97.33%~98.31%;随着降雨历时的增大,产流率和产沙率均呈现先增加后趋于稳定的趋势,2号基材坡面的产流率高于1号和3号基材,各基材坡面产沙率之间的差异较小;基材坡面的产流率与产沙率均与径流剪切力显著相关(p<0.05),随着径流剪切力的增加,基材坡面的产流率和产沙率均呈现出一定的线性增大现象;鉴于2号基材在抗侵蚀方面的良好效果,建议选作工程应用基材,海藻多糖、纤维、肥料、保水剂配比为1%∶0.8%∶3%∶0.9%。研究结果可为类似工程边坡防护提供新的材料与技术支撑,促进绿色工程建设和水土保持高质量发展。

[Objective] Algal polysaccharide is used as a curing agent in place of traditional cement, with the addition of corn fiber, water-retaining agents, and ecological fertilizers, to improve the ecological restoration performance of the substrate. In previous studies, the algal polysaccharide composite substrate has been preliminarily applied in the ecological restoration of slopes in red soil regions. However, there is still a lack of sufficient research on improving the erosion resistance of the algal polysaccharide composite substrates in red soil. This study aims to address the issues caused by the use of cement as a curing agent in sprayed vegetation techniques, including environmental pollution, difficulty in degradation, and restricted plant growth. [Methods] We selected the red soil slope of a power transmission and transformation project in southern China as the research subject. From previous 16 sets of orthogonal experiments, the best three types of substrates were selected for indoor simulated rainfall experiments. Rainfall intensities were set at 60, 90, 120 mm/h, and the slope gradients were set at 20° and 30°. With a bare slope treated only with clean water as the control group, a total of 72 rainfall experiments were conducted (2 slope angles×3 rainfall intensities×4 slope surfaces×3 repetitions), and the substrate with the best erosion resistance was ultimately selected. [Results] 1) Experimental results showed that on a 20° slope, when the rainfall intensity increased from 60 mm/h to 120 mm/h, the initial runoff yield time for substrates 1, 2, and 3 was shortened by 19.48%, 16.67%, and 30.43%, respectively, compared to the control group. The corresponding stable runoff yield rates were in the ranges of 0.56-2.08, 0.68-2.15,0.61-2.09 L/(min·m²), while the sediment yield rates at rainfall intensities of 60, 90, 120 mm/h were 0.18-0.22 L/(min·m²), 0.41-0.75 L/(min·m²), and 1.12-1.44 g/(min·m²), respectively. On a 30° slope, the initial runoff yield time was shortened by 25.80%, 48.48%, and 40.41%, respectively. The stable runoff yield rates were in the ranges of 0.63-2.21, 0.86-2.38,0.78-2.24 L/(min·m²), and the sediment yield rates under the corresponding rainfall intensities were 0.18-0.39 L/(min·m²), 0.68-0.86 L/(min·m²), and 1.27-1.77 g/(min·m²). 2) The drainage efficiency of the three substrates ranged from 16.35% to 52.73%, with substrate 2 showing the best performance, while the soil conservation efficiency remained stable at 97% to 98%. With increasing rainfall duration, both runoff yield rate and sediment yield rate exhibited a trend of first increasing and then stabilizing. The runoff yield rate of substrate 2 was higher than that of substrates 1 and 3, while the differences in sediment yield rates among the substrates were small. Both the runoff yield rate and sediment yield rate were significantly correlated with runoff shear force (p<0.05). As runoff shear force increased, both the runoff rate and sediment yield rate showed a linear increasing trend. Runoff shear force had the greatest impact on both runoff yield rate and sediment yield, with a significantly higher correlation compared to runoff power, resistance coefficient, and other factors, indicating that it was the primary controlling factor for runoff and sediment yield on the slope. [Conclusion] Algal polysaccharides significantly reduce the initial runoff yield time on substrate slopes, with the reduction becoming more pronounced as the slope angle or rainfall intensity increases. The runoff and sediment yield processes for different substrates under various slope gradients and rainfall intensities are generally consistent. Compared to bare slopes, runoff yield rates of substrate-covered slopes significantly increase, while the sediment yield rates markedly decrease. A significant positive correlation is observed between the runoff yield rate and the hydrodynamic parameters, especially with runoff shear force, which exhibits the highest correlation. However, except for runoff shear force, no significant correlation is found between sediment yield rate and other hydrodynamic parameters. Among the three test substrates, substrate 2 demonstrates superior erosion resistance and is recommended for engineering applications. The optimal formulation for this substrate is algal polysaccharide∶fiber∶fertilizer∶water-retaining agent=1%∶0.8%∶3%∶0.9%. The findings of this study can provide new materials and technical support for similar slope protection projects, promoting the development of green engineering and the high-quality advancement of soil and water conservation.