Water-induced disintegration is a critical issue in soil stabilization. In this study, soda residue (SR) and fly ash (FA) were mixed to improve the properties of high liquid limit clay (HLC), forming soda residue-fly ash stabilized clay (SRFSC), with cement and/or lime for further stabilization. The mix proportions of the SRFSC were optimized by the orthogonal method, using the compaction, unconfined compressive strength, shear, and disintegration tests. Meanwhile, microscopic tests were performed to reveal the possible mechanical mechanisms. The results showed that the SR and FA content are the primary determinants influencing the mechanical properties of SRFSC. When the base proportion is 70 % SR + 20 % FA + 10 % HLC, the strength is highest (2.45 MPa). At this proportion, the specimen with no cementitious material exhibits the best water disintegration resistance (WDR), reaching 107 min. Adding cement and lime can significantly enhance the WDR of the SRFSC, from complete disintegration at 0.28 min to remaining intact after soaking for 28 days. During field application, the cementitious materials content can be adjusted according to the actual conditions. The superior mechanical properties and WDR of SRFSC are mainly due to the good gradation and dense microstructure. The soda residue can provide abundant Ca2+ to enhance both the mechanical properties and WDR of SRFSC.

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.

Many single-use plastic (SUP) options made of synthetic polymers, bio-based materials, and blends of both are available in the market and used in large quantities. The disintegration of eleven commercial SUP, marketed in Mexico as cups and plates, was investigated in an aerobic home compost environment at a laboratory scale over 180 days. An evaluation of chemical changes, surface morphology, and thermal and mechanical properties was conducted to ascertain the original composition of SUP and the progression of disintegration in samples that are challenging to clean from soil contamination. Furthermore, the impact of residual compost on barley (Hordeum vulgare) plant growth and its correlation with the leaching of heavy metals were explored. The bio-based SUP, but not those made of expanded polystyrene foam, showed a correlation between the disintegration degree (measured by weight loss into particles <2 mm) and a decrease in functional groups (observed by FT-IR), mechanical-thermal stability loss, and surface wear over disintegration time. For instance, the highest disintegration at 180 days was approximately 70 % for wheat bran and palm leaf plates, followed by wheat plates and cellulose-PLA cups (60 %). In addition to the components listed by the manufacturers, the FT-IR and DSC analysis revealed the presence of polyethylene and polypropylene in cellulose cups and sugarcane plates. These components, impede disintegration but contribute to preserving thermal resistance and hydrophobicity during utilization. Compost derived from expanded polystyrene foam SUP, with 90 days of disintegration, was rich in zinc and chromium and significantly decrease in the root length of the barley plant compared to the control. This demonstrates the necessity of considering the impact of the leaching of additives and secondary microplastics into the environment.

The accumulation of plastics in the environment is a well-recognized issue. To address this, biodegradable materials such polylactic acid (PLA) have been developed. In natural environments such as soil or water, PLA degradation progresses slowly but steadily. To accelerate the degradation of the material, this study investigates the degradation of a biocomposite material using PLA as a matrix and Pennisetum setaceum fiber as reinforcement. Disintegration and marine biodegradability tests, both at the seawater/sediment interface and in marine sediment, were conducted. Different measurement tests were employed to quantify the degradation of PLA and composite samples, focusing on the mass loss and the variation of the mechanical and thermal properties. The results consistently demonstrated greater mass loss and mechanical property deterioration during the disintegration test compared to the marine biodegradability tests. Notably, the composite material exhibits more significant degradation than the pure polymer without fiber. For composite, the addition of fiber increased the degree of biodegradability compared to the plastic matrix.

The disintegration of expansive stiff clay will cause irreversible damage and deterioration of mechanical properties of the soil. The latest studies show that the disintegration is related to the swelling capacity of soil. In this study, a series of hydration disintegration tests and swelling pressure tests were performed on compacted Nanning expansive stiff clay samples with different initial water contents and dry densities. The observed disintegration process of all samples could be divided into initial, rapid and residual disintegration stages, among which the rapid stage dominated the whole process. By introducing relevant indicators to quantify the disintegration process, it was found that at a given dry density, the average disintegration rate of the sample decreased with increasing initial water content; while at a given water content, it decreased with increasing initial dry density. Such phenomena coincided well with the obtained evolution of swelling pressure at different initial water contents and dry densities. Based on these findings, the expansion-disintegration interaction mechanism of expansive stiff clay was finally analyzed from the perspectives of microstructure and hydration cracking. The initial conditions of the compacted samples determine the volume of inter-aggregates pores and thus the water transfer rate in soils, which affects the formation of hydration cracks. The cracking is induced by tension failure due to the expansion gradient formed during the hydration of sample, destructing the soil integrity to facilitate the disintegration. The disintegration, in turn provides preferential water infiltration channels to accelerate further soil expansion and hydration cracking. Such interactions proceeded until the completion of sample disintegration.

When operating in large drop pipelines, pipeline inspection gauge may experience severe impact vibration at elbows, potentially leading to its failure. This paper focuses on serial pipeline inspection gauges with multiple sections in large drop pipelines, analyzes the force acting on the pipeline inspection gauge during the descent phase, and establishes a multi-body dynamics model of the gauge under pipe-soil coupling conditions. In addition, a correction formula is developed for the pressure changes in the medium at the front and rear of the pipeline inspection gauge. To solve the model, MSC/ADAMS and MATLAB/Simulink are used for the bi-directional fluid-structure-interaction joint simulation. Moreover, the results are compared with the pipeline inspection gauge motion model established by OLGA. The study investigates the dynamic responses, vibration superposition and laws of dynamic evolution at the upper and lower elbows of the large drop pipeline. The results show that the speed of the gauge increases suddenly during the descent in large drop sections and then stabilizes, with different effects of the fluid medium pressure difference at various stages. The vibration responses along the axial, horizontal radial, and vertical directions at the elbows vary, with the second experiencing stronger vibrations due to superposition effects. Compared to fixed boundaries, the acceleration extremes of the gauge are lower under the constraints of pipe-soil model, indicating significant soil buffering and vibration damping effects.

Geological hazards such as gully erosion, collapse and slope failure occur frequently in loess areas, which are closely related to the soil disintegration characteristics. Understanding the impact of freeze-thaw and wet-dry action on soil disintegration in the context of climate change is essential to establish effective soil and water conservation strategies and prevent engineering geological hazards in loess areas. In this study, sodic-saline loessial soils with different clay content were subjected to freeze-thaw and wet-dry cycles, followed by aggregate durability tests, direct shear tests and disintegration tests to investigate the effects of the two natural processes on soil disintegration characteristics. The results showed that the samples subjected to freeze-thaw cycles primarily exhibited rapid and stable disintegration, followed by slow disintegration, whereas the samples subjected to wet-dry cycles revealed weight gain, continuous slow disintegration and eventual sudden disintegration. Freeze-thaw action continuously deteriorated the disintegration resistance of soil, while wet-dry action improved the disintegration resistance of soil after the first cycle, and gradually weakened it in subsequent cycles. Statistical analysis showed that, for samples undergoing freeze-thaw cycles, the number of cycles and clay content were positively correlated with the disintegration rate, while the aggregate durability was negatively correlated with the disintegration rate. For samples undergoing wet-dry cycles, the number of cycles had a positive effect on the disintegration rate, while the clay content, shear strength and cohesion had a negative correlation with the disintegration rate. At a certain clay content, there was a positive correlation observed between the surface crack ratio, crack length and width with the disintegration rate of the wet-dry samples, while shear strength and cohesion had a negative correlation with the disintegration rate of both freeze-thaw and wet-dry samples. Furthermore, the study outlined the disintegration mechanism of loessial soils based on internal factors, driving factors, resistance factors and evolutionary factors. This study contributes to the in-depth understanding of the catastrophic mechanism of geological hazards in cold and arid areas and provides experimental evidence for its control and management. The study outlined the disintegration mechanism of loessial soils based on internal factors, driving factors, resistance factors and evolutionary factors. image

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.