Understanding the swelling and shrinkage behavior of clay under freezing conditions is critical for mitigating frost damage in seasonally frozen and permafrost regions, yet current studies predominantly focus on freezinginduced swelling while overlooking systematic analysis of freezing-induced shrinkage. To address this gap, a series of freeze-thaw (F-T) cycling tests were conducted on clayey soil over a wide saturation range to establish fundamental relationships among degree of saturation (Sr), void ratio (e), number of F-T cycles (N), and freezinginduced deformation (epsilon v). The findings reveal that during multiple F-T cycles, clayey soils with varying void ratios all exhibit freezing-induced shrinkage/swelling under low/high degree of saturation, respectively. Notably, freezing shrinkage peaks at a specific low-saturation threshold before transitioning to swelling. Furthermore, a unique saturation point was identified at which no net deformation occurs. Given limited data availability in existing literature, conventional data-driven models show poor predictive performance. Thus, a hybrid model was proposed by integrating experimental evidence with physical mechanisms of freezing processes, enabling an accurate prediction of both global and local freezing characteristics with sparse data. The proposed data-driven modelling overcomes the need for training with a large amount of data or the dependence on the governing partial differential equations, thereby facilitating fast and robust model development to capture complex soil freezing-induced volumetric changes with less experimental and computational cost. The study provides valuable insights into the freezing-induced deformation of clayey soils and a solution for data-scarce modelling.

Wrapped woven geotextiles (WWG) have been widely used in engineering, while their filtration performance has not been investigated. To address this issue, a seepage test apparatus was innovatively developed based on the working mechanism of compressed WWG, which involves the coupled effects of geotextile tension and soil confining pressure. Seepage tests under monotonically increasing water head were conducted on three different soil-geotextile systems. Effects of compressive strain (epsilon C) and geotextile type on the velocity-gradient relationship, average hydraulic conductivity (ka), and post-test particle size distribution characteristics were systematically investigated. Test results show that the variation patterns of ka with epsilon C are primarily governed by the competition mechanism between the reduction of soil pore channels due to confining pressure and the enlargement of geotextile pores due to tension. For WWG with small pores, there is a potential for clogging when uncompressed. This clogging phenomenon is alleviated with increasing epsilon C, attributed to the enhanced soil erosion resistance provided by the confining pressure and the promotion of bridging structures facilitated by geotextile tension. Conversely, WWG with large pores faces a risk of piping, which can be mitigated by increasing the geotextile strength. These findings offer practical guidance for the filtration design of WWG.

Conventional methods for measuring geotextile hydraulic conductivity, such as the constant-head or falling-head methods, typically neglect nonlinear flow, thereby leading to measurement deviations. To address this issue, this study utilized a self-developed geotextile variable-head hydraulic conductivity apparatus coupled with image processing technologies to explore the pore structure evolution and hydraulic conductivity characteristics of plain (PG) and twill woven geotextiles (TG) under various tensile strains. The results reveal that the pores within PG exhibit a uniform distribution, while the pores of TG are predominantly oriented along the warp films. The relationship between geotextile porosity and tensile strain follows a linear function, while that between specific surface area and tensile strain is better described by a quadratic function. As flow velocity increases, the nonlinear flow behavior between flow velocity and hydraulic gradient becomes pronounced and can be described by the Forchheimer equation. The critical Reynolds number (Rec) generally increases with tensile strain, except for a reduction at 2% strain for PG attributed to the constriction of section pores. Based on the capillary tube theory, a predictive model for geotextile hydraulic conductivity is proposed. Experimental results are anticipated to contribute to improved filtration design for geotextile sand containers in ocean engineering.

Accurate characterization of gradation evolution and its influence on the critical state line (CSL) is essential for modelling the mechanical behaviour of widely graded granular soils. This paper aims to develop a constitutive model capable of depicting the stress-strain relationship and gradation evolution of widely graded granular soils. Firstly, a fractional breakage evolution model is formulated based on the observed breakage of fractional particle groups in artificially dyed granular soils. The model's capability to accurately reproduce gradation evolution is verified using three representative gradation datasets. Secondly, a gradation-dependent CSL is established to describe the downward shift of the CSL in the lne-lnp space based on the breakage-packing concept. Then, by incorporating the yield function of the microstructure and fractional-order plasticity theory, a state-dependent dilatancy equation is proposed, achieving a unified description of the loading and plastic flow directions. Finally, these components are integrated into a refined constitutive model for widely graded granular soils incorporating fractional particle breakage. Model predictions showed good agreement with triaxial test data for five granular soils under various loading conditions, demonstrating its robustness and applicability.

The resource recovery of waste scrap tyres has attracted growing attention from researchers in geotechnical disaster prevention and mitigation. Unlike previous studies using shredded rubber or processed tyre products, this study pioneers the use of whole scrap tyres as a cushion system, which preserves material integrity with near-zero processing energy while providing dual functions of drainage and confinement. A new method for reinforcing the foundation and mitigating liquefaction using scrap tyres was proposed. Three groups of small shaking table tests were conducted to verify the liquefaction resistance potential of the tyre cushion () under various drainage conditions. The tests demonstrated that the TC is feasible for liquefaction resistance due to its good drainage and deformation coordination performance. Furthermore, a simple method was introduced into the numerical simulation of the tyre unit. A numerical model capable of considering the deformation of the and the variation of additional cohesion was established. Numerical simulation results indicated that a certain area within the was susceptible to damage induced by liquefaction. Beyond the mechanical performance, an extended sustainability assessment demonstrated that the system substantially reduces environmental impacts, lowers repair costs, and aligns with circular-economy policies. The proposed technology therefore offers an integrated and scalable solution for sustainable geotechnical engineering.

Compaction quality control is essential for the safety of rockfill dams, yet traditional contact-type inspections suffer from invasiveness, spatiotemporal sparsity, and labor intensity. This study develops a non-intrusive visual framework for assessing rockfill compaction states under field conditions. The Rockfill Surface Compaction Condition (RSCC) dataset is established, systematically categorizing the visual characteristics of complex surface states throughout the construction lifecycle to provide a benchmark dataset for this task. Building on RSCC, a Transformer-based visual detection model, RockViT, is proposed to achieve precise classification of rockfill surface states. To address the challenge of long-tailed class distribution, a generative data augmentation strategy is employed using a Stable Diffusion (SD) model fine-tuned with Low-Rank Adaptation (LoRA). This process is optimized via Distribution-Alignment Parameter Optimization (DAPO) to improve the utility of the generated samples for minority-class learning. Experimental results demonstrate that RockViT outperforms the state-of-the-art (SOTA) learning models, achieving an overall accuracy of 96.24 % on the baseline dataset. Grad-CAM analysis indicates that RockViT captures both global context and subtle discriminative surface cues. The proposed framework offers a fast, accurate and end-to-end solution for identifying rockfill compaction states, particularly for defect identification. By linking visual recognition with physical validation, it supports targeted engineering actions and helps reduce detection difficulty and workload.

Pile-supported foundations reinforced with a soilbags raft cushion exhibit load transfer behaviors that are governed by contact-scale force redirection and fabric evolution within the granular layer; however, these micromechanical mechanisms cannot be directly resolved from physical model tests. In this study, a two-dimensional discrete element method (DEM) model is developed and calibrated against plane-strain model tests, and a contact-angle-based framework is introduced to quantify principal stress orientation and fabric anisotropy at the particle scale. By jointly considering the angular distribution of normal contact forces and the population of contact orientations, the principal direction and anisotropy of normal contact forces are obtained through fitting, enabling a direct characterization of stress redirection within the granular assembly. The validated model is applied to three loading scenarios, including pile-soil relative displacement, monotonic surface surcharge, and cyclic surface loading. Results indicate that the soilbags raft cushion promotes earlier formation of a stable load-transfer configuration under pile-soil displacement and significantly reduces fabric anisotropy within the stress adjustment zone. Under monotonic surcharge, the reinforced foundation maintains higher load transfer efficiency over a wider pressure range by delaying the deterioration of arching-mediated transmission. Under cyclic loading, force transmission adjusts rapidly in the first few cycles and then approaches a repeatable state; the evolution of the fitted principal direction and anisotropy captures this transition and clarifies the respective roles of strong and weak force chains. The proposed characterization establishes a quantitative link between particle-scale force transmission and macroscopic load transfer behavior, providing quantitative insight for the design and performance evaluation of soilbag-reinforced pile-supported foundations in transportation infrastructure.

Soilbags represent an emerging three-dimensional geosynthetic reinforcement technique, valued in permanent civil engineering for their structural strength, site adaptability, and economic efficiency. Despite growing application, the fundamental mechanisms of enhancing the deformation modulus of reinforced soil have not been fully elucidated. This study advances the understanding by integrating field, theoretical, and experimental approaches to unravel the modulus‑enhancement mechanisms. Field plate load tests on single‑layer soilbag‑reinforced foundation based on soil‑rock mixtures recorded an average increase in deformation modulus of approximately 23.4% compared to unreinforced soil-rock mixtures, confirming the technique's practical performance. A unified stress-strain framework is developed, which explicitly incorporates the additional confinement stress generated by geotextile tension and traces the resulting transition in stress paths of the encapsulated soil, thereby offering a mechanistic interpretation of modulus improvement. The framework is validated through unconfined compression tests on both clay‑ filled and sand‑filled soilbags, which further clarify how tensile confinement actively redistributes internal stress paths. The results reveal that the enhanced modulus arises from the coupled interaction between compressive hardening of the infilled soil and tensile confinement provided by the geotextile bag, offering a mechanistic basis for optimized design and application of soilbag reinforcement.

Variations in environmental humidity induce changes in the moisture content of rockfill materials, thereby influencing their creep behavior. In core rockfill dams, reservoir impoundment alters the environmental humidity conditions of the upstream rockfill materials, which often induces nonuniform creep deformation between the upstream and downstream zones. Excessive nonuniform creep deformation may lead to structural damage of the dam during its subsequent operation. This study presents an in-depth analysis of the impact of nonuniform creep deformation following reservoir impoundment on the long-term safety of an asphalt-concrete core dam exhibiting pre-existing crest cracks. To this end, a classical empirical creep model was modified to incorporate the humidity-dependent creep behavior of rockfill materials and subsequently integrated into a finite-element program for numerical analysis. Model parameters used in the modified creep model were identified using on-site monitoring data through the backpropagation-particle swarm optimization inversion method. The good agreement between the calculated results and existing monitoring data indicates the validity of the proposed numerical simulation scheme. Based on the simulation results, a thorough discussion is presented to clarify the causes of crest cracking and evaluate the safety of the dam. Stress analysis of the core crest pavement reveals that differential saturation levels on either side of the core wall induce tensile stresses in the pavement, which lead to cracking. Further stress analysis of the core wall suggests a low probability of cracking or hydraulic fracturing. Meanwhile, predictive deformation analyses indicate that creep deformation is expected to stabilize approximately 4 years after impoundment.

Crushed-compacted solidified sludge (CCSS) is a novel fill material produced by first chemically solidifying dredged sludge to a target strength, followed by crushing and compaction. A systematic investigation into the wet-dry durability of CCSS and the corresponding mitigation strategies is of great significance for its engineering application. In this study, CCSS specimens solidified with an industrial by-product-based curing agent (GCP, composing ground-granulated blast-furnace slag, calcium carbide slag, and phosphogypsum), as well as GCP combined with waste pulp fibers (WPF), were subjected to cyclic wetting and drying tests, with ordinary Portland cement (OPC)-solidified CCSS serving as a comparison. Variations in macroscopic appearance, mass and volume, unconfined compressive strength (UCS), splitting tensile strength (STS), deformation modulus (E50), and fracture energy (W), along with microstructural evolution characterized by X-ray diffraction (XRD), scanning electron microscopy with energy-dispersive spectroscopy (SEM-EDS), and low-field nuclear magnetic resonance (LF NMR), were analyzed to elucidate the degradation behavior of GCP-CCSS and the reinforcing mechanisms of WPF under wet-dry cycling. Results showed that GCP-CCSS exhibited lower mass and volume losses than OPC-CCSS under wet-dry cycling, and these losses were further mitigated by the incorporation of WPF. Throughout the cycling process, the UCS, E50, STS, and W of GCP-CCSS remained obviously higher than those of OPC-CCSS, while both mechanical stability and fracture energy were effectively enhanced by fiber reinforcement. Microstructural analyses revealed that GCP-CCSS initially contained abundant C-(A)-S-H gel and ettringite (AFt), which partially dissolved and disintegrated after 10 cycles, resulting in pore structure coarsening. In contrast, the incorporation of WPF effectively delayed microcrack initiation and propagation by enveloping soil aggregates and redistributing stress through interfacial friction among fibers, soil particles, and hydration products, thereby mitigating the detrimental effects of wet-dry deterioration.

To address the inadequate bearing capacity of crane operation platforms in wind farms constructed on soft ground and to promote the resource utilization of industrial by-products, this study employed ground granulated blast-furnace slag (GGBS), carbide slag (CS), and phosphogypsum (PG) to reinforce in-situ muddy soil, forming a solidified crust over soft ground (SCSG). The bearing behavior and environmental characteristics of the SCSG were comprehensively investigated. First, response surface methodology was adopted to determine the optimal mix proportion of GGBS, CS, and PG for the in-situ muddy soil, designated as GCP. Subsequently, a series of field plate loading tests, pH measurements, heavy metal leaching tests, and analyses of hydration products and microstructural morphology, were performed on both GCP-SCSG (GCP dosage of 70 140 kg·m−3 with treatment depths of 1.5 3.0 m) and ordinary Portland cement (OPC)-SCSG (OPC dosage of 100 kg·m−3 with a treatment depth of 2.0 m). The characteristic bearing capacity, deformation modulus, and stress diffusion angle of GCP-SCSG were comparatively evaluated against those of OPC-SCSG, while its environmental compatibility was assessed based on pH variation and the leaching concentrations of Cr, As, Ni, Cu, Zn, and Pb. Furthermore, the mechanisms of ground reinforcement and heavy metal stabilization by GCP and OPC were compared and discussed. The findings are expected to provide valuable references and practical insights for the effective utilization of industrial by-products in soft ground solidification.

The strength and deformation characteristics of rockfill materials are known to be closely related to their gradations.In order to predict the mechanical behavior of rockfill materials with different initial gradations,the influence of gradation on the mechanical properties of rockfill materials is first discussed within the framework of critical state constitutive theory.Subsequently,a method is proposed for rapidly predicting the initial and critical state void ratios for given gradations.Finally,by incorporating a state-dependent elastoplastic constitutive model,a prediction method for the gradation-related mechanical characteristics of rockfill materials is established.The results indicate that a good linear relationship exists between the minimum void ratio emin and the critical state void ratio ecs under low-stress conditions.Utilizing a particle packing algorithm,the critical state position of rockfill materials with specific gradations in the void ratio-pressure(e-p,e is the void ratio of the rockfill material in its current state,and p is the mean stress)space can be reliably predicted.Ultimately,this proposed prediction method facilitates the calibration of constitutive model parameters based on the test results of rockfill materials with known gradations,which subsequently allows for effective prediction of the mechanical behavior of other rockfill materials with different specified gradation profiles.

Organic matters lead to high water content of river sludge and difficulty in its deep dewatering. Flocculationprecipitation is considered as an efficient and low-cost dewatering technology. Flocculants play a key role in the dewatering process. This study employed anionic polyacrylamide (APAM) and lime as flocculant and conditioner for flocculation-precipitation dewatering treatment for river sludge with different organic matter content. Combination of response surface methodology (RSM) with CRITIC weighting method was used to determine the optimum flocculant and conditioner dosage, organic matter content. The results showed that the increase of organic matter content reduced the flocculation-precipitation effect of river sludge. APAM significantly enhanced particle size of the sludge and improved the flocculation efficiency. Lime effectively destroyed extracellular polymeric substances (EPS) and promoted the dewatering efficiency by providing Ca2+and adjusting pH, significantly reducing the absolute Zeta potential of the sludge and reducing turbidity of the supernatant by 9.36 times. The combined utilization of APAM and lime obtained higher dewatering efficiency than that using single APAM or lime. The optimum conditions were organic matter content of 4.92 %, APAM of 0.34 g/L, lime of 3.65 g/L). Turbidity of the supernatant, capillary water absorption time (CST) and median particle size (Dx(50)) of the sludge reached 2.77 NTU, 80.47 s, and 271.46 mu m, respectively. This study can provide valuable guidelines for flocculation-precipitation dewatering treatment of river sludge in real projects.

Sediment is a core part of lake ecosystems, and its organic matter (OM) content is a key indicator of lake ecological health and regional carbon cycling. OM provides nutrients for phytoplankton and algae in water, thereby influencing the degree of lake eutrophication. However, excessively high OM content may trigger water eutrophication, alter sediment’s physical and chemical properties, and ultimately threaten the stability and health of ecosystems. This study innovatively selected Poyang Lake, Taihu Lake, Qinghai Lake, and Hulun Lake from China’s four major geographical regions to systematically investigate sediments’ OM content, sources, and distribution characteristics at different times. The results showed that the organic matter content of sediments in lakes from different regions varied significantly and was influenced by multiple factors, such as watershed characteristics, eutrophication levels, human activities, and climate change. Poyang Lake and Taihu Lake, characterized by high levels of agricultural activities and urbanization within their basins, exhibit significant fluctuations in organic matter content, with total organic carbon (TOC) levels ranging from 0.35% to 2.9% and 0.7% to 2.4%, respectively. In contrast, Qinghai Lake and Hulun Lake, influenced by natural conditions and ecological policies, show relatively stable TOC levels, ranging from 1.3% to 2.75% and 1.25% to 3.58%, respectively. By analyzing sediments’ OM content and combining methods such as organic carbon, nitrogen isotopes, and organic C/N ratios, it is possible to effectively assess the ecological health of lakes, provide critical data support for pollution control, and play a significant role in carbon cycle management.

Accurate calibration of mesoscopic contact parameters in granular materials is essential for elucidating their multiscale mechanical behaviors and enhancing the design of geotechnical structures. This study proposes a novel self-adaptive framework integrating Box-Behnken Design (BBD), Non-dominated Sorting Genetic Algorithm II (NSGA-II), and DEM simulations for efficient parameter inversion and particle shape characterization. By replacing conventional DEM-intensive iterations with surrogate regression models embedded with a dynamic self-correction mechanism, the proposed method achieves an 81

Application of solidified river sludge for ecological slope protection is important way for recycling river sludge. Evaluation on their environmental characteristics under nature conditions is an essential work, which may be significantly affected by rainfall. This study aimed to study the environmental characteristics of in-situ solidified river sludge used as matrix of ecological slope protection under natural rainfall conditions. Impact of traditional cement (CC) and composite solidifiers (GCP) on the solidification effect of pollutants solidifying agents and the environmental characteristics of the solidified river sludge were also discussed. The results indicated that rainfall led to the formation of pore structures in the solidified sludge, causing the leaching of contaminants such as nitrogen, phosphorus, and heavy metals. Simultaneously, rainfall reduced the HA/FA ratio in the CC and GCP solidified sludge by 37.78 % and 34.25 %, respectively, affecting its aggregation stability, fertilizer-holding capacity, and growth of dogtooth grass. The total leaching amounts of total phosphorus (TP), total nitrogen (TN), and total organic carbon (TOC) from GCP solidified sludge were 9.05, 98.32, and 539.49 mg/kg, respectively. Its accumulated leaching amounts of heavy metals (Cr, Ni, Cu, Zn, As, Pb) were lower than that from CC solidified sludge. After rainfall, GCP solidified sludge produced more calcium silicate hydrate gel (C-SH) and ettringite (AFt) to fill pore structures, which effectively enhanced its structure stability. Furthermore, the dogtooth grass growing on GCP solidified sludge exhibited higher photosynthetic (7.1 x10- 4 mg/g of chlorophyll (a+b) content) and growth capacity than that on CC solidified sludge (3.7 x10- 4 mg/g). The number of beneficial microorganisms such as Bradyrhizobium, Rhodobacter, and Gemmatimonas in GCP solidified sludge increased after rainfall. Thus, GCP solidified sludge exhibited stronger tolerance to rainfall and higher ecological friendliness than CC solidified sludge. The findings of this study provide reference for recycling solidified river sludge in ecological slope protection.

The freezing point of expansive soils is a critical thermal parameter for designing artificial ground freezing systems, optimizing infrastructure insulation, and modeling thermo-hydro-mechanical processes in cold regions, yet it remains poorly characterized due to complex mineral compositions and hydro-thermal interactions. This study combines systematic laboratory experiment and mechanistic analysis to elucidate how water content, dry density, cooling mode, and sample size influence freezing behavior and freezing point evolution of expansive soils. Results show that cooling curves can be categorized into four distinct types, and the curve morphology is strongly governed by initial water content and cooling mode. The freezing point of expansive soil increases sharply with rising water content, which significantly contrasts with the experimental findings of sand, dispersive saline soil, and ordinary clay. Dry density, cooling mode, and sample size exert negligible influence on the freezing point but markedly alter supercooling behavior and phase transition characteristics. Additionally, the mechanistic basis for these behaviors was well elucidated, linking microscale soil properties to macroscale thermal responses. The findings enhance the mechanistic understanding of freezing in expansive soils and offer practical guidance for engineering in freeze-thaw susceptible regions.

The interfacial mechanical properties of frozen soilbag-expansive soil play a key role in the long-term stability of the expansive soil slopes reinforced by soilbag in seasonally frozen regions. However, the freezing effect on shear behavior of soilbag-expansive soil interface is still unclear. In this study, a series of large-scale temperature-controlled direct shear tests was conducted on frozen soilbag-expansive soil samples with different temperatures (-15℃, -10℃, -5℃ and -2℃) and normal stresses (25kPa, 50kPa, 100kPa and 200kPa). Effects of temperature and normal stress on failure morphology, shear stress–shear displacement relationship, volume change behavior, and shear strength characteristics are analyzed. Two primary areas can be distinguished on the soilbag-expansive soil interface: the contact surface area (CSA) between the woven bag and expansive soils, and the embedded soils area (ESA). The shear failure displacement (δp), friction angle (θ), maximum dilation angle (ψmax), interface cohesion and interface friction angle are used to quantify the shear behavior of frozen soilbag-expansive soil interface. Furthermore, the evolution mechanism of stress-dilatancy characteristics and the influence of the embedded soils are discussed. The experimental findings are expected to provide theoretical insights for the construction and operation of expansive soil slopes reinforced by soilbag in cold regions. Large-scale temperature-controlled direct shear tests on frozen soilbag-expansive soil interface were conducted. Freezing effect on shear behavior of soilbag-expansive soil interface was explored. Stress-dilatancy behaviors of frozen soilbag-expansive soil interface were analyzed. The influence of the embedded soils on shear strength of frozen soilbag-expansive soil interface was discussed.

Blasted rock material serves a critical role in various engineering applications, yet the phenomenon of segregation-where particle sizes vary significantly along the gradient of a quarry pile-presents challenges for optimizing quarry material storage and handling. This study introduces an advanced image analysis methodology to characterize such segregation of rock fragments. The accurate delineation of detailed rock fragment size distributions was achieved through the analysis of drone-captured imagery, coupled with the application of an enhanced Unet semantic segmentation model integrated with an expansion-based post-processing technique. The quarry slope was stratified into four vertical sections, with the size distribution of each section quantified via ellipsoid shape approximations. Our results disclose pronounced vertical segregation patterns, with finer particles concentrated in the upper slope regions and coarser particles in the lower. Utilizing relative characteristic diameters, we offered insight into the degree of segregation, thereby illustrating the spatial heterogeneity in fragment size more clearly. The techniques outlined in this study deliver a scalable and accurate method for assessing fragment size distribution, with the potential to better inform resource management and operational decisions in quarry management.