摘要
采用有限差分软件FLAC3D对有无植被及淤地坝的黄土高原小流域重力侵蚀机理进行探索,揭示了主要工程措施(淤地坝)和生物措施(植被)对重力侵蚀的调控机制。通过对比分析无治理措施和实施淤地坝及生态恢复治理措施条件下,小流域位移场、应力场和塑性屈服区分布,揭示了淤地坝和植被措施减缓重力侵蚀的作用。结果表明:植被可使梁峁顶处位移减9.8%,沟坡中下部位移减小11%,淤地坝只能使坝址处位移减少10%;植被可使塑性区体积减少46%,淤地坝可使塑性区体积减少11%。淤地坝增加了流域的凹形边坡,而根系加固作用改善了坡面浅层土体应力,二者均有效降低了坡面土体的应力集中,减少了塑性屈服区体积,但均未改变小流域以剪切破坏为主的屈服模式。小流域小尺度范围内,淤地坝减蚀作用强于植被,而大尺度范围内,植被减蚀效果优于淤地坝。研究成果可为小流域水土保持措施的合理配置提供科学依据。
Mechanism of gravitational erosion in small watersheds with or without vegetation or check dam on the Loess Plateau was explored with the aid of FLAC3D , a finite difference software, so as to reveal mechanisms of some major engineering measures （building of check dams） and biological measures （maintenance of vegetation） regulating gravitational ero- sion. By comparing watersheds with and without controlling measures in distribution of displacement field, stress field and plastic deformation zone, effects of check-clam and vegetation reducing gravitational erosion were explored. Results show that hat vegetation may reduce displacement of hill tops and mid/lower slopes by 9.8% and 11% , respectively, while a check dam could only reduce displacement of the dam site by 10%. Moreover, vegetation could reduce volume of the plastic zone by 46% while a check dam could do only by 11%. A check dam increased concave slopes, while vegetation or roots rein- forcement improved surface soil mass stress, both being able to reduce stress concentration of the soil mass on the slope and volume of the plastic deformation zone, but unable to alter the yielding model dominated by shear failure in the small water- shed. However, within a small-scale range of a small watershed, the effect of a check dam was better than vegetation in erosion reduction, whereas in a large-scale range, it was just the reverse. The findings of the research can be cited as scientific basis for rationalization of the disposition of soil and water conservation measures for a small watershed.
出处
《土壤学报》
CAS
CSCD
北大核心
2012年第4期646-654,共9页
Acta Pedologica Sinica
基金
国家自然科学基金项目(40872208
40971161)
国土资源部科研专项项目(201111020)
中国博士后基金项目(2011M501445)资助
关键词
小流域
重力侵蚀
植被根系
淤地坝
调控机理
Small watershed
Gravitational erosion
Vegetation root
Check-dam
Regulating mechanism
