Traditional materials such as fly ash and lime are generally used to improve soils but can severely pollute the environment. Eco-friendly protocols, such as the application of xanthan gum, are therefore essential for soil treatment. In this study, a series of microscopic tests, water retention characteristics tests, and shear tests were carried out on silt, which are known to have poor engineering properties, to explore the effect and mechanism of xanthan gum treatment on the water retention and shear strength characteristics of silt during the wetting process. The results show that the water retention capacity of the treated silt increases with increasing xanthan gum content, and a hysteresis effect is clearly observed. The cohesion and internal friction angle of the silt strongly decrease with increasing water content, and the strength significantly weakens. However, the strength of the silt treated with xanthan gum is consistently higher than that of the untreated silt. The microscopic tests show that soil pores are gradually filled by xanthan gum with good water-retaining properties, thus significantly enhancing the water retention capacity. Furthermore, the hydrogel that cements the soil particles forms by the bonding effects between xanthan gum and soil particles, which greatly improves the silt strength.

Vegetation slope protection is widely used in slope support engineering as an ecologically friendly support method. There has been a lot of research on herbs and shrubs slope protection, but less on arbor slope protection. Using accumulation landslides as a research subject, a series of physical model tests of arbor slope protection were conducted, using a combination of various monitoring technologies and 3D printing technology that can produce realistic root models. The slope protection effect of arbors and the synergistic characteristics of accumulation landslides were explored using a preliminary analysis. We found that, with the support of arbor roots, (1) the peak-start stage, second peak stage, variable attenuation stage, and linear attenuation stage were the four stages of the anti-sliding force curve. The peak value of anti-sliding force on a slope with root protection increased, and the time it took to reach the peak value increased dramatically. Furthermore, after attaining the peak value, the degree of anti-sliding force attenuation was diminished. (2) The slope displacement showed a downward trend. Moreover, the coefficient of variation of displacement curves in different parts decreased, and slope integrity was enhanced. (3) The degree of slope crack growth diminished, resulting in an arch stress area and improved anti-sliding capacity. (4) There was an apparent “synergetic” tendency in the evolution process of accumulation landslides. Furthermore, the anti-sliding force and displacement curves in different parts had a good correspondence.

Perilous rock instability on the soil slope brings a substantial threat to project operation and even people’s lives. The buried depth of the perilous rock is a challenge to deal with and primarily determines its stability, and the indirect rapid identification of its buried depth is the key to its stability evaluation. The paper aims to find a new and quick method to measure the buried depth of perilous rock on the soil slope and to solve the hard-to-measure buried depth stability evaluation. When the damping ratio is less than one, and the deformation is linear elastic throughout the amplitude range, the potentially perilous rock vibration model may reduce to a multi-degree-of-freedom vibration one. By theoretical deduction, a quantitative relationship is established among the perilous rock mass, the basement response coefficient, the buried depth of the perilous rock, and the natural horizontal vibration frequency. In addition, the accuracy of this relationship is confirmed via numerous indoor experiments, showing that the horizontal vibration frequency of the perilous rock model in one dimension increases as the buried depth increases. Finally, based on the natural vibration frequency and guided by the limit balance model, a stability evaluation model of the perilous rock on the soil slope is constructed. Hence, the example shows that the method is feasible. The research findings are of vital significance for the stability evaluation of the perilous rock on the soil slope and give a novel approach and theoretical foundation for quick identification and monitoring.