Fissured loess slopes along the railway in the Loess Plateau frequently suffer from disintegration disasters under the coupled effects of rainfall and train vibrations, causing soil collapse that covers tracks and severely threatens railway safety. To reveal the disaster mechanisms, this study conducted water-vibration coupled disintegration tests on fissured loess using the self-developed EDS-600 vibration disintegration apparatus, based on the measured dominant vibration frequencies (12-46 Hz) of the Lanzhou-Qinghai Railway. The influence patterns of vibration frequency (f) and fissure type (t) on disintegration rate (S), disintegration velocity (V), and disintegration velocity growth rate (\documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$$\alpha_{f - t}$$\end{document}) were systematically investigated, with scanning electron microscopy (SEM) employed to uncover microstructural evolution mechanisms. Results indicate that vibration frequency and fissure type significantly accelerate disintegration: V reaches its maximum at f = 20 Hz, and under the same frequency, V increases with the growth of fissure-water contact area. Under two fissures and f = 20 Hz, V increases by 225% compared to the without vibration and fissures scenario, with the \documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$$\alpha_{f - t}$$\end{document} value peaking at 137.23% and the synergistic effect index exceeding the single-factor superposition value by 45.99%. Microscopically, water-vibration coupling disrupts clay mineral cementation, reconstructs pore networks, and forms dominant seepage channels, leading to reduced interparticle bonding strength, heterogeneous water film distribution, and stress concentration, thereby inducing fractal propagation of secondary fissures and shortening moisture absorption and softening stages. Combined with unsaturated soil mechanics theory, the study reveals a cross-scale progressive failure mechanism involving simultaneous degradation of matric suction, cementation force, and macroscopic strength. A theoretical framework integrating vibration energy transfer, seepage migration, and structural damage is established, along with a quantitative relation linking vibration frequency, fissure parameters, and disintegration velocity. This provides multi-scale theoretical support for disaster prevention and control of railway slopes and foundations in loess regions.

Dispersive soil is highly susceptible to water erosion, leading to significant engineering challenges, such as slope instability and canal damage. Common modifiers such as lime are effective but cause environmental pollution. Therefore, it is important to explore eco-friendly modifiers. This study investigates the effects of sticky rice and calcium chloride (SRC) on dispersive soil. Dispersivity tests identified an optimal ratio of sticky rice to calcium chloride of 3:1. To analyze the effects of different SRC contents and curing times on the soil properties, tests of dispersivity, hydraulic, mechanical, chemical, and microscopic mechanisms were conducted based on this optimal ratio. The results indicated that 1.5% SRC effectively eliminated soil dispersivity even without curing, and its effectiveness improved with an extended curing time. After 28 days of curing, the water stability increased significantly, permeability decreased by an order of magnitude, and cohesion improved by approximately 85.97%. SRC reduced soil dispersivity through three primary mechanisms: lowering the pH, promoting ion exchange between Ca2+ and Na+, and the cementing effect of the sticky rice paste. Additionally, Ca2+ acted as a bridge between organic colloids and clay particles, further strengthening the structural stability of microaggregates. Overall, SRC proved to be an effective eco-friendly modifier for improving physicochemically dispersive soil.

Disintegration fragments the loess body, causing erosion and the emergence of significant geohazards. The impact of vibrations on soil disintegration has been slightly documented; however, the contribution and mechanism of train vibration frequency in the disintegration of undisturbed loess remain unclear. In this study, train vibrations were monitored in situ, and the resulting vibrational parameters were used in loess disintegration tests using a customised vibration-disintegration apparatus. The changes in the meso-parameters of the disintegrated loess and aqueous solutions were quantified, and the microstructural differences in the residual loess after disintegration were compared under non-vibrating and vibrating conditions. The results revealed that train vibrations in the loess progressively diminished with increasing distance from the track, with dominant vibration frequencies ranging from 17 to 49 Hz. Increasing the vibration frequency accelerated loess disintegration and enhanced the dispersion of the disintegrated fragments. Notably, the acceleration effect of disintegration was particularly pronounced in the early stages of increasing vibration frequency, and it tended to plateau above 15 Hz. The relationship between the vibration frequency and disintegration velocity (DV) of loess influenced by the initial water content can be expressed as a power function with variables. Vibrations accelerate loess disintegration primarily attributed to repetitive particle displacement and the vibrations of free water in the pores which lead to frictional damage to the weakly cemented structure and pore expansion. Higher vibration frequencies generate greater inertial forces and facilitate more frequent particle jumps, allowing the loess to reach the disintegration threshold conditions more readily than at lower frequencies. These findings provide theoretical value for the prevention and mitigation of water-induced loess geohazards and land degradation in vibrating environments.

Due to the high degree of weathering, the red clay slope has low anti-disintegration performance, and the clay easily becomes wet and disintegrates after soaking in water. It causes geological problems such as slope collapse caused by soil softening. To study the disintegration characteristics of modified red clay, the disintegration test of red clay modified by using lignin fiber, clay particles and lime was carried out, analyzing the disintegration characteristics of improved red clay from physical and chemical perspectives and analyzing the improvement mechanism of three modifiers with the scanning electron microscopy test. The analysis results show that the water-holding capacity and disintegration resistance of soil mixed with lignin fiber decrease; the disintegration time of reshaped red clay increases with the increase in clay content; and the average disintegration rate of the soil decreases with the increase in clay content. With the increase in lime content, the soil cement increases. The integrity of the soil is enhanced, and its anti-disintegration ability is improved; the saturated moisture content of reshaped red clay increases with the increase in lignin fiber and clay content, while the saturated moisture content of soil decreases with the increase in lime content. The damage analysis shows that the larger the damage factor of soil, the worse its anti-disintegration ability, and the easier the soil disintegrates. The purpose of this paper is to explore the essence of the soil disintegration phenomenon, and on this basis, using high-quality improved materials, to improve the soil, which easily disintegrates. This move aims to significantly enhance the anti-disintegration ability of the soil, thereby improving its resistance to softening and disintegration, thereby effectively improving and maintaining the ecological environment. At the same time, the improved soil will help to improve the utilization rate of the slope and foundation soil, thereby reducing the economic cost of maintenance engineering. Against the current background of sustainable economic, social, and ecological development, it is of great strategic significance to ensure the sustainable availability of land resources in specific areas and maintain their productivity and ecological stability for a long time. The research into this subject not only helps to deepen the understanding of soil disintegration, but also provides strong technical support for the rational utilization of land resources and the protection of the ecological environment.

The complex structure of Neogene mudstone plays an important role in geological disasters. A close relationship exists between the mechanisms of mudstone landslides and the disintegration characteristics of rocks. Therefore, understanding the disintegration characteristics of Neogene mudstone at different depths is crucial for enhancing engineering safety and assessing landslide stability. This study employed Neogene mudstone from different depths to perform disintegration and plastic limit experiments and revealed the sliding mechanisms of landslides involving Neogene mudstone, providing theoretical support for mitigating mudstone geological disasters. Our results demonstrate that Neogene mudstone from different depths experiences varied stress conditions and pore water pressure due to geological actions, significantly affecting the disintegration characteristics. By ignoring the factors of the slip surface, the slake durability index of mudstone decreases with increasing burial depth, while the plasticity limit index tends to rise. The influence of groundwater, geo-stress, and pore structure on Neogene mudstones at different depths results in overall weak stability and disintegration. Landslide occurrences are likely connected to the mechanical properties of mudstones at the slip surface, where a low slake durability index and higher plasticity index make the mudstones prone to fracturing, breaking, and disintegrating once in contact with water.