Purpose

Soil moisture plays an important factor to impact runoff and the slope stability, but how vegetation affects the soil moisture variability of slope stability is poorly understood. In order to compare the stability of different shrub slopes under the effect of soil moisture, four types of shrubs (Periploca sepium, Lespedeza bicolor, Ziziphus jujuba, and Punica granatum) are selected for ecological restoration in shallow landslide-prone areas, and the effects of rhizosphere soil moisture and plant roots on the slope stability are studied.

Materials and methods

Trace infiltration is applied in order to study plant roots and soil moisture impact. The shear strength of the roots slope soil under different moisture content is determined by laboratory shear strength test. The slope safety factor of different shrubs is obtained by FLAC 3D (Fast Lagrangian Analysis of Continua 3D) simulation.

Results and discussion

Among the four shrubs, thick roots show the greatest improvement to soil porosity, and fine and medium roots could provide more preferential flow channels for water infiltration. The soil moisture content significantly increases after planting Lespedeza bicolor. At 10% soil moisture content, the P. sepium slope safety factor is highest in four shrubs (1.39). When the soil moisture content reaches 30%, the safety factor value of the L. bicolor slope reaches the maximum, and the safety factor value of L. bicolor decreased by 25.6%.

Conclusions

The results show that even during the wettest condition of the soil (saturated soil moisture content 30%), the mechanical reinforcement form the L. bicolor root maintains some degree of stability. Shrubs have a good effect on enhancing the stability of slopes, especially in areas prone to shallow landslides.

中文翻译：

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浅层滑坡易发区种植植被土壤水分对边坡稳定性影响的评估

目的

土壤水分是影响径流和斜坡稳定性的重要因素，但植被如何影响斜坡稳定性的土壤水分变异性却知之甚少。为比较不同灌木坡度在土壤水分作用下的稳定性，选取了4种灌木（紫花胡枝子、胡枝子、枣树和石榴）在浅层滑坡易发区进行生态修​​复，并评价其效果。研究了根际土壤水分和植物根系对边坡稳定性的影响。

材料和方法

应用微量渗透以研究植物根系和土壤水分影响。不同含水率下根系坡土的抗剪强度通过室内抗剪强度试验确定。通过FLAC 3D（Continua 3D的快速拉格朗日分析）模拟获得不同灌木的边坡安全系数。

结果和讨论

在四种灌木中，粗根对土壤孔隙度的改善作用最大，细根和中根可以为水分渗透提供更优先的流道。种植双色胡枝子后土壤含水量显着增加。在 10% 的土壤水分含量下，P. sepium斜坡安全系数在四种灌木中最高 (1.39)。当土壤水分含量达到30％时，安全系数值L.双色斜率达到最大值，并且安全系数值L.双色下降25.6％。

结论

结果表明，即使在土壤最潮湿的条件下（饱和土壤含水量 30%），来自双色紫苏根的机械加固仍保持一定程度的稳定性。灌木对提高边坡的稳定性有很好的作用，特别是在容易发生浅层滑坡的地区。