Research on the shallow landslide stability of vegetated slopes with expansive soils based on root morphology

Expansive soil slopes are often subject to shallow landslides, and soil bioengineering techniques are commonly used to reinforce shallow expansive soils, while the slope stability analysis methods used in soil bioengineering techniques lack the consideration of expansive forces and the biomechanical effect of root systems. In order to accurately analyze the shallow landslide stability of vegetated slopes with expansive soils, firstly, a 3D growth model of the root system of Oleander was constructed based on the principle of l-system, and then laboratory experiments and mechanical analyses were carried out on the reinforcing and anchoring roles of the root system and the distribution of the expansive force in the slope respectively, so that the shallow stability analysis method of slopes with the consideration of the root system role and the expansive role was established, and finally, the engineering case was carried out to verify the results. The study shows that: the tensile strength of the oleander root system has an increasing power index relationship with the root diameter, and the shear strength of the root-soil compsite has a positive correlation with the root area ratio (RAR); the three-dimensional growth model of the oleander root system based on the l-system predicts the morphology of the oleander root system and the growth parameters, and the predicted depth of the 3-year-old's oleander root system can be up to 70 cm; the shallow stability of slopes occurs after taking into consideration of the role of expansive force After considering the effect of expansive force, the shallow stability of the slope will be significantly reduced by 37.78 %, and the use of soil bioengineering technology can improve the shallow stability of the slope by 36.01 %; finally, the effects of root density, root type and soil depth on the stability of the slope are discussed, so as to verify the validity of use of the soil bioengineering technology to manage the expansive soil slope.