降雨入渗下根带土水力特性及边坡稳定性研究

Study on Hydraulic Characteristics of Root Zone Soil and Slope Stability Under Rainfall Infiltration

摘要

为研究降雨入渗条件下根带土水力特性及植被对边坡稳定性的影响，构建灌草协同植被群落恢复模式，对根带土进行直剪试验以量化植被根系加固效应，并借助降雨冲刷试验分析植被护坡效应，同时运用fish语言对FLAC3D软件进行二次开发，开展降雨与根系耦合作用下非饱和边坡稳定性变化的研究。研究结果表明：（1）灌草协同下植被根系可显著提高土体抗剪强度，使土体黏聚力提升85.20%，且在降雨冲刷下植被可有效抑制坡面侵蚀；（2）在降雨作用下，植被边坡能减缓雨水入渗，延缓土体饱和所需时间，同时协同根系力学加固效应抑制潜在滑移面上移幅度，使安全系数衰减幅度较裸坡减少37%；（3）不同降雨入渗方式、降雨强度及坡度下植被护坡效应差异显著，在强降雨及陡坡状态下，边坡安全系数大幅下降；（4）研究揭示了植被力学与水力协同增效的护坡机制，建议在灌草协同护坡模式下弃土场边坡坡度宜控制在45度以内，为山区地质灾害防治提供科学依据。

Abstract

In order to study the hydraulic characteristics of root zone soil and the influence of vegetation on slope stability under rainfall infiltration, this paper constructs a restoration model of shrub-grass synergistic vegetation community, conducts straight shear tests on root zone soils to quantify the effect of vegetation root reinforcement, and employs rainfall scouring tests to analyze the effect of vegetation slope protection. Furthermore, it uses fish language to perform the secondary development of FLAC3D software, enabling the study of the unsaturated slope stability under the coupling effects of rainfall and root system. The results show that: (1) The root system of vegetation under shrub and grass synergy can significantly enhance the shear strength of the soil, increasing soil cohesion by 85.20%. Additionally, vegetation can effectively inhibit slope erosion under rainfall washout; (2) Under rainfall conditions, the vegetation slope can slow down rainwater infiltration, delay the time required for soil saturation, and, combined with the mechanical reinforcement effect of roots, inhibit the upward shift of potential sliding surfaces. This results in a 37% reduction in the rate of safety factor decay compared to bare slopes; (3) The slope‑protection effectiveness of vegetation varies significantly under different rainfall infiltration modes, rainfall intensities, and slope gradients. Under heavy rainfall and steep slope conditions, the slope safety factor decreases substantially; (4) The study reveals synergistic slope‑protection mechanism combining the mechanical and hydraulic effects of vegetation. It is recommended that under the shrub‑grass synergy model, the slope gradient of spoil‑field slopes should be controlled within 45 degrees. This provides scientific guidance for the prevention and control of geological hazards in mountainous areas.

关键词

降雨入渗 / 根土复合体 / 水力特性 / 边坡稳定性 / 数值模拟

Key words

Rainfall infiltration / root-soil composite / hydraulic performance / slope stability / numerical simulation

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基金资助

云南省交通厅项目(云交科教便［2022］4号)