根-土复合体岸坡渗流及稳定数值模拟

Numerical simulation of seepage and stability in root-soil composite slopes

植物护岸中根系力学效应可显著提高岸坡浅层稳定性,但对降雨和水位变化等条件下,根系水力效应与力学效应之间相对关系变化对岸坡浅层稳定性影响的研究较少。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)、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,进一步分析了不同水力特性条件下根-土复合体对岸坡浅层稳定性的影响。模拟计算结果表明:(1)在设定的3种降雨强度下,根-土复合体的优先流入渗作用与降雨强度和降雨时间均呈正相关,而排水作用与降雨强度和降雨时间均呈负相关。在长历时的小降雨或短历时的强降雨情况下,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-土复合体排水作用有滞后性,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。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,也应加强坡面排水和坡体排水措施。

The mechanical effects of root systems in vegetative bank protection can significantly enhance the shallow stability of slopes.However,research on how changes in hydraulic and mechanical effects of roots under conditions such as rainfall and water level fluctuations impact shallow slope stability is limited.This study employs numerical analysis methods to simulate the hydraulic effects of root-soil composites on slope seepage fields during transitions from unsaturated to saturated states(rainfall conditions and rising water levels)and from saturated to unsaturated states(falling water levels).Additionally,the influence of root-soil composites on shallow slope stability under different hydraulic characteristics is analyzed.The simulation results indicate that:(1)Within the three specified rainfall intensities,the preferential infiltration effect of root-soil composites is positively correlated with rainfall intensity and duration,while the drainage effect is negatively correlated with both.Under prolonged light rainfall or short-duration heavy rainfall,the negative impact of the hydraulic effects of root-soil composites predominates due to the increased depth of rainfall influence.(2)Under falling water levels,the drainage effect of root-soil composites exhibits a lag,with mechanical effects remaining dominant;under rising water levels,the infiltration effect of root-soil composites strengthens with increasing water level rise rates,gradually overshadowing the mechanical effects.These findings provide valuable insights for the application of vegetative bank protection engineering.Even when using ecological vegetative bank protection,it is essential to enhance surface and subsurface drainage measures.