Canadian Geotechnical Journal, Ahead of Print.
A large volume of research reporting the pull-out behaviour of root systems is available, but no study has considered the effects of soil drainage. This work implemented a modified three-dimensional embedded beam element model in a finite element platform that solved model equations by using a fully hydromechanically coupled algorithm. The model was validated against published centrifuge pull-out tests on root analogues, and the validated model was then applied to study parametrically the influence of the ratio of uplift rate to soil hydraulic conductivity on pull-out behaviour. The results demonstrated that the model can well capture the prepeak behaviour of the root systems up to the peak pull-out resistance. The generation of negative pore–water pressure (pex) owing to soil dilation upon root–soil interfacial shearing was the major reason for increased pull-out resistances under partially drained conditions. Compared with other root systems, root systems with smaller branch angles and deeper branch depths mobilised considerably more significant plastic deviatoric strains in the soil in their vicinity, generating more negative pex. Hyperbolic dimensionless backbone curves were derived to explain the transitional pull-out behaviours of root systems of different geometries under drainage conditions that ranged from fully drained to undrained.

中文翻译：

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膨胀土壤中植物根部部分排水的抬升行为

加拿大岩土工程杂志，印刷前。
有大量研究报告了根系的拔出行为，但没有研究考虑土壤排水的影响。这项工作在有限元平台中实现了改进的三维嵌入式梁单元模型，该模型使用完全流体机械耦合算法求解模型方程。该模型根据已发表的类似根的离心机拔出试验进行了验证，然后应用验证的模型来参数化研究抬升率与土壤导水率之比对拔出行为的影响。结果表明，该模型可以很好地捕获根系的峰值前行为直至峰值拔出阻力。由于根-土界面剪切引起的土壤膨胀而产生负孔隙水压力（pex）是部分排水条件下拔出阻力增加的主要原因。与其他根系相比，具有较小分枝角度和较深分枝深度的根系在其附近的土壤中动员了更显着的塑性偏应变，产生更多的负 pex。推导出双曲无量纲主干曲线来解释不同几何形状的根系在从完全排水到不排水的排水条件下的过渡拔出行为。