# Shear Strength Analysis and Slope Stability Study of Straight Root Herbaceous Root Soil Composite
###### Abstract
\begin{table}
\begin{tabular}{c c c} \hline \hline
**Reference** & **Test Equipment** & **Observed Root-Soil Synergistic Effects** \\ \hline [PERSON] et al. (2023) [11] & Direct shear equipment & Under the action of 5\% and 10\% moisture content, _Eleusine indica_ can significantly improve the shear strength of soil, and the root-soil interface exhibits the highest-friction characteristics. \\ [PERSON] et al. (2023) [12] & Direct shear equipment & The shear strength of the root-soil composite is four times that of rootless soil. \\ [PERSON] et al. (2023) [13] & Direct shear equipment & The cohesion of the root-soil composite with a root content of 0.71\% increased by 50\% compared to rootless soil, and the ductility increased by 37.5\% compared to rootless soil. \\ [PERSON] et al. (2023) [14] & Triaxial shear equipment & The shear strength of the root-soil composite can reach up to 1.18 times that of rootless soil, and the influence of roots on the internal friction angle of the soil is more significant than that of cohesion. \\  & & The shear strength of the root-soil composite of _Dolicho LablabL._ and \\ [PERSON] et al. (2023) [16] & Direct shear equipment & rootless soil, respectively. The cohesion trend is _Dolicho LablabL._ (31.64 kPa) \(>\)_Medicago sativa_ (26.35 kPa) \(>\) rootless soil (10.92 kPa), and there is no significant difference in the internal friction angle. \\ [PERSON] et al. (2022) & Triaxial shear equipment & The cohesive force of _Medicago sativa_ root-soil composite can reach up to twice that of rootless soil. \\ [PERSON] et al. (2021) & Direct shear equipment & The shear strength trend of the four studied herbaceous plants is _Stipa_ \\ (2021) [18] & Direct shear equipment & _pururea Griseb_ (39.34 MPa) \(>\)_Kobresia mysuroides_ (25.98 MPa) \(>\)_Leontopodiumanum_ (25.31 MPa) \(>\)_Ajania tenifolia_ (12.72 MPa). \\ [PERSON] et al. (2021) [15] & Direct shear equipment & The maximum soil fixation effect of corn roots can reach six times that of barley roots. \\ [PERSON] et al. (2020) [19] & Direct shear equipment & The shear strength of the root-soil composite can reach up to 1.36 times that of rootless soil with an increase in plant root content. \\ [PERSON] et al. (2019) [20] & Direct shear equipment & When the root system acts on sandy soil, it increases the cohesion by 234\%. \\ (2019) [20] & Direct shear equipment & When the root system acts on the clay, it increases the cohesion and internal friction angle by 32\% and 14.4\%, respectively. \\ \hline \hline \end{tabular}
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Table 1: Summary of research on the characteristics of plant root-soil complexes. the soil internal friction angle and cohesion via triaxial compression tests [24; 25]. A similar study by [PERSON] et al. on root soil strength adopted a direct shear apparatus [26; 27; 28]. [PERSON] et al. conducted indoor triaxial shear tests on undisturbed loess under different moisture contents and remolded loess with roots. The authors explored the impact of different root distribution modes on the shear strength performance of remolded loess [29]. [PERSON] et al. performed shear tests on herbaceous root-soil composites in loess areas to investigate the relationship between the shear displacement and strength of soil-root composites at different depths and soil moisture contents, revealing the mechanical friction effect between roots and soil [30]. [PERSON] et al. conducted compression and triaxial compression tests on cohesionless roots and soil system-reinforced composite soil under wet-dry cycling conditions and explored the impact of the root system and wet-dry cycling number on the shear strength indexes of soil-reinforced composites [31]. [PERSON] et al. investigated the shear characteristics of the native soil-root composite of the dominant species belonging to the family _Iridaceae (genus Iris)_ in the source area of the Lanniqing landslide in Zhaotong, China, using direct shear tests. The results were compared with those of indoor reshaping composite tests using the same moisture content [32].