Inclusion of root water absorption and reinforcement in upper bound limit stability analysis of vegetated slopes

• Published in: Computers and geotechnics 2024-05, Vol.169, p.106227, Article 106227
• Main Authors: Cheng, Ping, Wu, Lizhou, Zhang, Hong, Zhou, Jianting
• Format: Article
• Language: English
• Subjects: Slope stability; Steady transpiration; Upper bound limit analysis; Vegetated slopes
• ISSN: 0266-352X; 1873-7633
• DOI: 10.1016/j.compgeo.2024.106227

Vegetation plays an important role in improving slope stability. It is crucial to develop simple and effective methods for assessing the stability of vegetated slopes. Based on upper bound limit analysis, a method was proposed to analyse the stability of a two-dimensional vegetated slope with uniform root architectures under steady transpiration state. The effects of water absorption and reinforcement by vegetation roots on slope stability were considered using this method. Parametric studies were performed to investigate the effects of the soil type, root depth, plant transpiration rate, root tensile strength, slope angle and internal friction angle on slope stability. Several generic stability plots were provided. The results showed that roots significantly improved soil cohesion but slightly affected the internal friction angle. Root systems could provide additional soil cohesion. Horizontally and vertically distributed roots imposed the best mechanical reinforcement effect on the soil. The shear strength increases by 1.78 times. Compared with that of plain soils, the critical state line (CSL) of the root–soil composite moved upwards. The soil type strongly influences the pore water pressure. With increasing plant transpiration rate, root tensile strength and root depth, vegetated slope stability can increase by 58 %. The slope stability decreases by 50 % with increasing slope angle. The stability number (Ns) decreases with increasing internal friction angle. The effects of water absorption and reinforcement by roots on slope stability decrease with increasing desaturation coefficient and saturated permeability coefficient. Compared with that of loess and sand slopes, the reinforcement effect of vegetation roots is more significant for the stability of clay slopes.