| 摘要: |
| 在进行植物护岸时，根系力学效应可显著提高土体抗剪强度以及岸坡浅层稳定性，但是在降雨和水位变化等不同水作用条件下，根系的水力效应与力学效应谁占主导尚无定论，根-土复合体对岸坡渗流和稳定性的影响如何，值得探讨。本文首先采用数值分析方法模拟了岸坡根-土复合体从非饱和到饱和（降雨工况和水位上升工况）以及从饱和到非饱和（水位下降工况）过程中根-土复合体水力效应对岸坡渗流场的影响，然后进一步计算分析了不同水作用条件下根-土复合体对岸坡浅层稳定性变化的影响。计算模拟结果表明：（1）在本文设定的三种降雨强度内，根-土复合体的优先流入渗作用、排水作用与降雨强度和降雨时间分别呈正相关和负相关。在小降雨、长历时以及强降雨、短历时的情况下，由于降雨影响深度增大，根-土复合体水力效应带来的消极影响占主导地位。（2）在水位下降工况下，根-土复合体排水作用呈滞后性，力学效应仍占主导地位；在水位上升工况下，根-土复合体增渗作用随水位上升速率增加而增强，根-土复合体的力学效应逐渐被水力效应所掩盖。本文的研究结果对植物护岸工程应用具有借鉴意义，即使采用植物生态护岸，也应该加强坡面排水和坡体排水措施。 |
| 关键词: 根-土复合体 优先流 降雨影响深度 水位变化 岸坡非饱和土 |
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| 基金项目:国家自然科学基金项目（面上项目，重点项目，重大项目） |
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| Numerical Simulation of Root-soil complex effect on seepage and stability of bank slope under Rainfall or Water Level Variation |
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Liu ran1, 周成1, chen yuan1, zhong qiming2, he ning2
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1.State Key Laboratory of Hydraulics and Mountain River Engineering, College of Water Resources and Hydropower, Sichuan University;2.Nanjing Hydraulic Research Institute, Nanjing
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| Abstract: |
| Root mechanical effects can significantly improve soil shear strength and shallow slope stability in vegetated bank slopes. Which predominates the slope stability is interesting, among the hydraulic and mechanical effects of roots. However under various water circumstances such as rainfall and water level fluctuations, there is no definitive evidence. It is important to investigate how vegetation roots affect seepage and the stability of bank slopes. Numerical calculation is conducted in which root-soil complex is adopted, to demonstrate how the hydraulic effect of roots would affect the seepage field of bank slopes from an unsaturated to a saturated state (condition of rainfall and water level rise) and from a saturated to an unsaturated state (condition of water level fall). The impact of vegetation roots on the improvement of shallow stability of bank slopes under various water action circumstances is further calculated and analyzed. The simulation results show that: (1) the permeability-increasing effects and drainage effects resulting from preferential flow of root-soil complex are positively and negatively correlated with rainfall intensity and rainfall duration, respectively, within the three rainfall intensities chosen in this paper. In weak rainfall with a lengthy duration or intense rainfall with a short duration, due to the increased depth of rainfall infiltration, the hydraulic effects of root-soil complex are detrimental. (2) When the water level is dropping, the drainage effects of root-soil complex are hysteresis, but the mechanical effects are still the more important ones. The root-soil complex has permeability-increasing effects under conditions of rising water levels, and these effects grow faster while the water level rises. The mechanical effect of the root-soil complex is gradually covered by the hydraulic effects. The findings from this study can be useful for vegetated bank slope engineering, suggesting that slope drainage measures should be improved, even when vegetative revetment techniques are applied. |
| Key words: root-soil complex preferential flow rainfall infiltration depth water level fluctuations bank unsaturated soils |
