Due to the dense structure and low permeability of saline-alkali soils with high clay content, the vertical migration of water and salt within the soil profile is severely restricted, posing considerable difficulties for saline-alkali land amelioration. To address the aforementioned deficiencies of shallow saline-alkali soils, this study proposes directly incorporating river sand with a specific particle size gradation into the shallow layer of saline soil to reconstruct the soil skeleton and improve pore connectivity. Through laboratory soil column leaching tests and direct shear tests, the incorporation ratio of river sand was systematically optimized, and the evolution of the microstructure before and after amelioration was characterized by scanning electron microscopy. The results indicate that incorporating river sand with a particle size of 0.075-1.0 mm at an incorporation rate of 20%-30% can significantly shorten the leaching duration and effectively promote the vertical transport of water and salt. Furthermore, compared with unamended saline soil, sand-amended saline soil exhibits improved pore structure and permeability, with the pore network becoming coarser and progressively more open, thereby forming continuous and efficient drainage and salt-discharge channels. Notably, an incorporation rate of approximately 30% represents a critical threshold for the evolution of cohesion; once this threshold is exceeded, the system response mechanism undergoes a transition, and cohesion enters a recovery phase. The technical approach proposed in this study is economical, practical, and broadly applicable, demonstrating promising application prospects not only in the fields of saline-alkali land remediation and ecological restoration, but also providing a reliable scientific basis and an efficient solution for relevant engineering practice.

The large-scale accumulation of coal gangue has led to severe ecological risks and resource waste, while underground backfilling provides a promising pathway for its in-situ utilization. However, the coupled mechanisms of slurry flow, microstructural evolution, and reinforcement effectiveness during gangue-based grouting remain insufficiently understood. This study aims to systematically investigate the flow characteristics, filling effectiveness, and structural response of high-concentration coal gangue slurry in pipeline transport and grouting processes, in order to provide theoretical and technical support for its efficient and sustainable resource utilization. A multi-scale coupled simulation framework integrating the Euler-VOF model and the discrete element method (PFC) was established. Particle size distribution was optimized based on the Fuller-Thompson theory, and slurries with solid volume fractions of 60 %-80 % were modeled. The effects of particle size and concentration on flow trajectories, disturbance intensity, porosity evolution, and displacement fields were analyzed. The results indicate that increasing concentration leads to more concentrated particle trajectories, reduced radial and Z-directional disturbances, and enhanced flow stability. Smaller particles (0.3 mm) exhibit better streamline adherence and shorter residence times, whereas larger particles (0.5 mm) deviate more due to inertial effects. PFC simulations show that grouting induces plume-like diffusion, increases porosity, restructures particle skeletons, and reconstructs force chains, thereby improving load-bearing capacity and stability. The optimized borehole layout effectively suppresses displacement in the overlying strata and reduces high-displacement zones. Engineering application in the Longwanggou Coal Mine demonstrates that five boreholes can accommodate 1.323 Mt. of coal gangue and reduce COQ emissions by approximately 0.992 Mt. This work confirms that optimizing particle grading, slurry concentration, and borehole arrangement enables large-scale, in-situ, and high-efficiency disposal of coal gangue. The findings provide a feasible and scalable technical pathway for safe and sustainable backfilling, with substantial ecological and carbon mitigation benefits.

ABSTRACT In the arid and semi‐arid sandy loess area, farmland wind erosion is exacerbated by spring strong winds and long‐term tillage, yet the pathways by which crop roots regulate soil properties and wind erosion resistance remain unclear; to address this, we conducted controlled experiments combining root‐soil composite preparation and wind tunnel simulations, where soil samples were mixed with foxtail millet roots to form root volume density ( RVD ) gradients of 0%, 0.2%, 0.4%, 0.6% and 0.8% and then exposed to wind speeds of 8–11 m/s at attack angles of 0°, 15° and 30° for 30–120 min, with soil mechanical properties and wind erosion characteristics measured. Results showed that wind erosion intensity decreased exponentially with increasing RVD (maximum 42.7% reduction in the initial stage at 10 m/s wind speed compared to bare soil), soil cohesion increased logarithmically from 3.7 kPa (bare soil) to 9.8 kPa (0.8% RVD ), root‐induced additional shear strength contributed 47.5%–158.67% of total shear resistance, soil erodibility ( K ‐value) declined from 2.61 (bare soil) to 1.49 (0.8% RVD ) and root reinforcement mitigated erosion by 44.8%–47.7% across all attack angles. Although erosion intensity decreases with the increase of RVD , it rises with the increase in wind speed. Mechanistic analysis revealed RVD indirectly regulated wind erosion intensity and erodibility by improving soil structural stability and mechanical properties, with RVD identified as the primary factor controlling wind erosion resistance and wind velocity dominating erosion dynamic attenuation, and we established a nonlinear empirical equation for erodibility parameters and RVD incorporating wind velocity and attack angle. This study clarifies root‐mediated wind erosion control mechanisms and provides a low‐cost, sustainable soil conservation strategy for ecologically fragile sandy loess regions.

As part of the world cultural heritage, rammed earth sites have long been subjected to natural factors such as wind erosion and weathering, leading to damages like holes and cracks that threaten their structural stability and cultural value. Traditional restoration materials face limitations in material compatibility and color discrepancy control. The innovative application of Microbially Induced Carbonate Precipitation (MICP) technology in the restoration of rammed earth sites offers several advantages. This study focuses on the microbial mineralization restoration of wind erosion damage on rammed earth sites based on MICP technology. The results demonstrated that, introducing bio-based materials at different stages of the MICP process led to significant improvements. The optimal incorporation rates were determined to be 2% for corncob powder and 1% for calcium lignosulfonate. Both types of factors (wind speed gradient and wind vector direction) exert significant effects on the deterioration processes of various types of wind erosion damage. The wind erosion mass of the mineralized specimens was consistently lower than that of the plain soil specimens, and the wind erosion resistance rate remained above 40%. Typical wind erosion damages of rammed earth sites exhibit two deterioration behaviors in response to wind speed gradients. MICP technology can alter the deterioration behaviors and effectively reduce wind erosion intensity. This study develops a stable and safe restoration material for rammed earth sites through modified MICP technology, proposing an innovative approach to preserving carriers of civilization and perpetuating cultural heritage. It offers theoretical guidance for protecting and enhancing the historical, cultural, and multifaceted values of ancient sites.

To elucidate the hydro-mechanical evolution of rainfall-triggered loess-mudstone interface landslides and improve monitoring and early warning, we conducted a large-scale indoor physical model test under artificial rainfall conditions. The model was instrumented with pore-water pressure and earth pressure sensors, as well as terrestrial laser scanning (TLS) for spatially continuous, hourly displacement mapping. XRF/XRD and mechanical tests were adopted to quantify the water-induced softening characteristics of mudstone.The results show a power-law increase in water absorption and rapid strength degradation, with the unconfined compressive strength decreasing from 4.90 MPa to 0.82 MPa within 3 h. Rainfall promotes the formation of an interfacial water film and argillation of mudstone, which weakens inter-particle bonding and significantly reduces the interface shear strength, representing the key trigger for sliding. Pore-water pressure evolves quasi-synchronously with rainfall but with a slight lag, exhibiting a three-stage pattern: stable - accelerated rise - rapid decline. TLS captured deformation precursors at the crest and slope surface at approximately 1560 min, providing a 140-min lead time over sensor-detected anomalies (approximately 1700 min).TLS-derived displacement fields cross-validate with pressure-based indicators to characterize progressive destabilization, which culminates in failure under continuous rainfall. This study clarifies the water-film-controlled softening mechanism and demonstrates the superior early-warning sensitivity of TLS for interface-type landslides, providing a scientific basis for multi-index fusion monitoring and the formulation of refined early-warning thresholds.

The Loess Plateau, a worldwide recognized ecologically sensitive region, with slope-gully systems (SGS) serving as primary sediment sources due to their unique erosion dynamics. However, quantifying the partitioning of sediment contributions between slope and gully subsystems remains poorly understood. This study examines erosion mechanisms and sediment budgets in a 26 km2 SGS watershed. We assessed slope erosion contributions using data from multiple sources, including remote sensing, field surveys, and historical records. Concurrently, the sediment-trapping capacities of five check dams were calculated using geotechnical field measurements, allowing gully erosion estimation. The results demonstrated differential erosion partitioning, with annual sediment yields of 10,550 t a-1 (30.8%) from slope systems and 23,735 t a-1 (69.2%) from gully systems, showing gully dominance in sediment production. Results show gully systems dominate sediment production (69.2%), with check dams reducing gully slope lengths by 18-32% and vegetation roots enhancing shear strength biome chanically. Furthermore, biomechanical reinforcement by arboreal vegetation within dam sediments was identified, with root structures that functionally emulate anti-slide pile systems. These findings establish vegetation restoration and strategic dam placement as complementary interventions for slope and gully erosion reduction, respectively, providing insights into soil erosion control strategies in the Loess Plateau's agricultural areas.

Soil contamination caused by mining activities may pose potential risks to human lungs. This study investigated the pollution levels and inhalable bioaccessibility of selected metal elements in the soils of Bayan Obo, a representative mining city, and Baotou, an industrial city in China. The human health risks of metal elements were also evaluated. The results indicated that La, Ce, and Eu exhibited the highest levels of enrichment, with significant spatial variations. The inhalable bioaccessibility of the metals followed the order: As>Mn>Ni>Pb approximate to Zn>Cu>Cr>La>Ce>Eu. Health risk assessment results indicated that evaluating human health risks based on total metal concentrations rather than bioaccessible concentrations could not only overestimate the risk of soil metals but, more critically, lead to misidentification of high-risk pollutants. The measured inhalable bioaccessibility data revealed that both non-carcinogenic and carcinogenic risks for children and adults were below safety thresholds, with Mn and As being the primary contributors to non-carcinogenic and carcinogenic risks, respectively.

Soil reinforcement and improvement based on microbial-induced calcium carbonate precipitation (MICP) technology in highly saline–alkaline environments has emerged as a new research focus in geotechnical engineering. However, the effectiveness of MICP is often limited by issues such as soil porosity, microbial cell size, weak compatibility between calcium carbonate crystals and soil particles, and the low environmental tolerance of conventional urea-hydrolysing bacteria. These factors represent critical bottlenecks in applying MICP to fine-grained and highly saline–alkaline soils. In this study, a high-yield urease strain, designated ZN1#, was isolated, and its potential application in MICP for saline soil was investigated. The mineralisation products, growth characteristics, urease activity, solidification effect, unconfined compressive strength (UCS), shear strength, calcium carbonate content, and soluble salt content of the solidified soil were evaluated. Results indicated that ZN1# strains exhibited a broader environmental tolerance than traditionally mineralised strains under chloride, sulfate, and chloride-sulfate mixed salt conditions. Saline soil columns treated with ZN1# achieved superior compressive and shear strengths, with UCS increasing by 16.23 times, cohesion by 13.48 times, and the internal friction angle by 1.92 times compared to untreated saline soil. Furthermore, comparing the curing strength under different soil particle groups, it was found that the ZN1# enhanced performance in finer soils, particularly in silty clay, where curing strength reached 4.397 MPa. Additionally, the total soluble salt content in saline soil reinforced by ZN1# decreased by 13.14%. This study demonstrates that ZN1# holds significant potential for application prospects in microbial reinforcement of saline soils, soil improvement, and fine-grained soil reinforcement. By overcoming the limitations associated with the environmental tolerance of traditional mineralised strains, this research provides a novel and sustainable strain for MICP technology. It introduces a new paradigm for its application in fine-grained soil.

Baotou, a city renowned for its steel production and rare earth resource development, is facing significant threats from heavy metal pollution in its urban soils. This study analyzed nine soil samples from urban Baotou to assess the bioavailability of heavy metals, including rare earth elements (REEs), As, and Pb, and evaluate the environmental risks posed by these elements in soils. The bioavailabilities of REEs, As, and Pb were quantitatively examined through in vitro simulated digestion experiments involving physiologically based extraction tests (PBET) and in vitro gastrointestinal (IVG) methods. The results indicate that the bioavailability of REEs is relatively low, with higher bioavailability observed in PBET tests compared to IVG tests. Overall, the REE bioavailability was lower than those of As and Pb, and the REE bioavailability was higher in the gastric phase than in the gastrointestinal phase. Speciation analysis revealed that approximately 80% of the REEs were present in the residual fraction. Meanwhile, the non-residual fractions were primarily composed of carbonate-bound, Fe/Mn oxides-bound, and strong organic matter-bound REEs, exchangeable REEs accounting for less than 0.5%.

Urban soil samples were collected from the major heavy industrial city of Baotou in Inner Mongolia, China, to investigate the concentration, spatial distribution, and pollution levels of heavy metals. The study employed the geoaccumulation index (Igeo), ecological risk index, and spatial interpolation methods to comprehensively assess urban soil pollution. The results indicated that apart from arsenic (As) and nickel (Ni), the concentrations of heavy metals such as cadmium (Cd), chromium (Cr), manganese (Mn), mercury (Hg), copper (Cu), zinc (Zn), and lead (Pb) were significantly higher than the corresponding background values in the study areas. According to the geoaccumulation index (Igeo), the overall pollution level in the study area ranged from uncontaminated to low pollution. However, variations existed among different urban districts. Among Baotou’s four main urban areas, the soil pollution level in Kundulun District was notably higher compared to the other three urban areas. Mercury (Hg), lead (Pb), zinc (Zn), and copper (Cu) exhibited relatively higher pollution levels across the four district sites. The observed pollution characteristics are closely linked to the distinct industrial attributes of the urban districts: the Kundulun District of Baotou, Inner Mongolia, is renowned for its significant presence of industrial activities such as steel manufacturing, power generation, and coal combustion. These industries play a crucial role in the local economy but also contribute substantially to heavy metal emissions, leading to notable environmental impacts. Similar to the Kundulun District, the Qingshan District of Baotou, Inner Mongolia, is significantly influenced by industrial activities, which have led to elevated concentrations of certain heavy metals and formed higher potential ecological risk index (PERI) hotspots. Implications and Recommendations. The disparity in industrial activities across the four urban districts of Baotou is a principal factor contributing to variations in pollution levels and ecological risks. In conclusion, this research highlights the necessity of aligning industrial zoning with effective environmental management strategies to combat heavy metal pollution in urban soils. By implementing these integrated approaches, Baotou can safeguard its environment and public health, paving the way for a sustainable future.

Mobile sand dunes have been recognized as quite tricky natural disaster in Central and Western China. Consequently, proposing an effective and environmentally friendly method to combat mobile sand dunes is of great significance. In this study, a combined technology, enzyme-induced carbonate precipitation (EICP) and sand plants, is proposed to control the mobile sand dunes. Laboratory experiments and large-scale on-site tests were conducted to demonstrate the feasibility of this combined technology to improve the success rate for treating mobile sand dunes. The results showed that using a first spray solution before germination with concentrations of 0.05 mol/L (calcium source solution) and 10 g/L (urease solution), the sand plants (Alfalfa, Astragalus, and Sarcozygium) had an optimal germination rate. For the second spray solution after germination, it is recommended to employ a solution comprising 0.05 mol/L, 40 g/L at an application amount of 4 L/m2 (spray amount), using a one-phase injection method to improve the spray efficiency, which had the highest strength, the best water retention, and the best erosion resistance. Therefore, wind erosion resistance during on-site test was significantly improved, and the desert sands in the Ulanbuh Desert were not affected by wind for 60 days or more. The results demonstrated that combined technology was effective in preventing mobile sand dune movement, which presents promising potential for wide application in desert area.

Varied slope structures have different landslide initiation mechanisms. However, the role of interfacial asperities in controlling sliding initiation is unclear. This study develops a novel analytical method for interface mechanisms in practical landslide scenarios. Based on asperity theory, theoretical derivations were conducted, yielding an equilibrium equation grounded in the maximum shear length of asperities (Llimit). A method was proposed to evaluate slope stability by integrating Llimit with monitored displacement data. On-site displacement monitoring and slope state analysis determined the distribution range of asperities, providing theoretical support for slope remediation. Between July 2023 and July 2024, a large landslide located in Shagudu Town, Zhungeer Banner, Ordos, Inner Mongolia, underwent multiple deformation stages. This landslide seriously affected the operations of the Rongwu Expressway. This study initially examined the geological structure of the landslide through geological drilling and surveys. The distribution of asperities in the landslide area was determined through physical and mechanical tests and on-site geological mapping. A layout plan for landslide disposal and monitoring points was developed based on the interface landslide asperity theory. Analysis of 20 days of displacement monitoring data was used to determine asperity distribution and analyze slope movement, informed by asperity theory. This study pioneers the systematic application of asperity theory as the primary framework for analyzing and managing a large-scale interface landslide in engineering practice. Its rationality and effectiveness are rigorously demonstrated through the successful determination of the asperity distribution range within the Rongwu Expressway landslide, leading to effective remediation and favorable monitoring outcomes. This work not only validates the asperity theory for interface landslides but, crucially, establishes a novel, practical method for their stability assessment. Furthermore, a key theoretical advancement is the development of the concept that asperity-controlled main sliding surfaces can induce secondary sliding surfaces, based on field evidence and analysis.

Microbially induced calcium carbonate precipitation (MICP) technology can induce calcium carbonate crystals with cementation and stable performance in the process of microbial metabolism or enzymization through the regulation of environmental factors MICP can be used as a cementing agent to cement cohesionless sand particles to form the materials with the characteristics of higher strength, better durability and environmental friendliness, as well as a good engineering application prospect. In this paper, the shear strength of sand column was tested by triaxial compression tests, and the strength index was obtained. In order to further study the micro strength mechanism and the failure process, based on the discrete element method, a numerical model of MICP cemented sand column was established considering the factors of matrix soil particle gradation, particle morphology, content ratio of induced calcium carbonate, pore distribution characteristics, inter-particle cementation and so on. The failure process of MICP cemented sand column under load was analysed by numerical simulation, and the reliability of the numerical model was tested by combining with the stress intensity curve of samples under test conditions. The results indicate that compared with the actual triaxial tests of MICP cemented sand column, although there are deviations in stress and strain, cohesion and internal friction angle, the numerical simulation shows similar development law and intensity amplitude, and the same failure trend. The work in this paper verifies the reliability of the numerical model and provides a theoretical basis for the subsequent analysis of the factors influencing the geotechnical mechanical properties of biomineralized materials.

This study systematically investigates the failure mechanism of interfacial landslides through experimental validation and engineering applications of interfacial asperity theory. An innovative scaled physical modeling approach was developed, incorporating artificially prefabricated asperities along the sliding interface. Using 3D laser scanning to monitor slope deformation, the physical experiments provide the first direct evidence linking asperity rupture to landslide initiation. The interfacial asperity theory proves particularly effective in analyzing the three recurrent landslides along the Hushuo Expressway (2012-2017), where conventional engineering treatments failed, as all cases exhibited characteristic interfacial sliding mechanisms. The results reveal the nonlinear slip mechanisms of interfacial landslides: the first failure was controlled by asperities at the slope toe, the second by asperities at the slope crest, and the third by structural asperities. Due to post-failure excavation at the site, numerical simulations were employed to reconstruct the failure process, successfully reproducing the controlling effects of different asperity types on landslide evolution. The study also proposes the concept of targeted monitoring and early warning for interfacial landslides.The findings offer a novel theoretical perspective for understanding the progressive failure mechanisms of interfacial landslides and provide critical insights for the design of landslide mitigation measures.

The Ordos coalfield contains shallowly buried coal seams, with sandstones in the overlying strata. Mining activities induced extensive fissures in the overlying rock and on the surface; thus, groundwater and surface water migrated through these fissures, accumulated within the mines and working faces, and diminished the surrounding rock strength. To reveal the failure patterns of the overlying sandstones and to explore a reliable method for monitoring rock layers and providing early disaster warnings, sandstones from the No. 2-3 coal seam in the Naoerhao Coal Mine were studied. With electrical resistivity and acoustic emission data acquired during the loading processes, experiments were conducted on the sandstones from the coal seam roof in both dry and water-saturated states. A method for predicting the failure strength of the water-saturated sandstones using the response of the resistivity standard deviation (RVSD) was developed. The results indicated that (1) the mechanical properties of the sandstone samples decreased significantly after water saturation; (2) a very strong correlation was observed among the acoustic emission, electrical resistivity, and stress during the loading process of the water-saturated samples; (3) introducing the RVSD to determine the rock closure strength and its combination with the corresponding stress level relative to the peak stress was an effective way to estimate the peak strength of the rock samples; and (4) based on the change in the number of acoustic emission hits within a unit of time, the locations of the precursor points to failure for sandstone were determined. Our proposed method for determining the characteristic points during the loading process of rock samples conforms to the principles of electrical resistivity and acoustic emission testing and can be easily adopted. This study can provide a reference for early warning systems for the sandstone roof failure in shallowly buried coal seams.

The Yellow River Basin, as a crucial water and ecological zone, is threatened by environmental contamination from the Bayan Obo tailings dam located just 13 km away. Based on the Microbial-Induced Calcite Precipitation, this research used a combined approach of bio-mineralization and bio-sorption to bio-remediate the rare earth elements (REEs) and their mixed contaminants. Optimal conditions for soil solidification and stabilization are determined through solution pretests. Comparative analyses of adsorption, mineralization, and their combined processes were conducted in soil experiments. Evaluating using the results of speciation analysis. Following bioremediation, the adsorption-mineralization group involving indigenous bacteria, Bacillus oceanicus, exhibited the best performance. In this group, the average comprehensive reduction in exchangeable forms of Zn, Pb, La, and Ce was 52.02%, which is 2.9 times that of the adsorption group and 1.3 times that of the mineralization group under the same environmental conditions. These results indicate that the biogenic carbonates and isomorphic lattice substitutions generated through the bioption and bio-mineralization process contribute to the solidification/stabilization of REEs and their mixed contaminants. This approach holds significant importance for environmental protection and ecological restoration in the Yellow River Basin, particularly in the middle and lower reaches of the Yellow River.

Loess-mudstone landslides are common in the Loess Plateau. Investigations into the mechanical theory of loess-mudstone landslides have become a challenging undertaking due to the distinctive interfacial properties of loess-mudstone and the unique water sensitivity characteristics of mudstone. Hence, it is imperative to develop innovative mechanical models and mathematical equations specifically tailored to loess-mudstone landslides. In this study, we analyze the fracture mechanism of the loess-mudstone sliding zone using plastic fracture mechanics and develop a unique fracture yield model. To calculate the energy release rate during the expansion of the loess-mudstone interface tip region, the shear fracture energy G is applied, which reflects both the yield failure criterion and the fracture failure criterion. To better understand the instability mechanism of loess-mudstone landslides, equilibrium equations based on G are established for tractive, compressive, and tensile loess-mudstone landslides. Based on the equilibrium equation, the critical length Lc of the sliding zone can be used for the safety evaluation of loess-mudstone landslides. In this way, this study proposes a new method for determining the failure mechanism and equilibrium equation of loess-mudstone landslides, which resolves their starting mechanism, mechanical equilibrium equations, and safety evaluation indicators, thus justifying the scientific significance and practical value of this research.

The degradation of cave murals due to saline-alkali conditions still poses a formidable challenge in the realm of cultural heritage conservation. This research proposes a novel methodology grounded in microbial mineralization technology. By leveraging Bacillus oceanicus, a newly isolated strain, calcium carbonate precipitation is induced under saline-alkali conditions, forming a protective layer. Experimental outcomes demonstrate that, in contrast to the conventional strain Bacillus pasteurii, B. oceanicus showcases exceptional salt tolerance. Its salt tolerance level in an identical saline environment is twice as high as that of B. pasteurii. Additionally, B. oceanicus can significantly enhance the mechanical properties of specimens. When compared with B. pasteurii, the unconfined compressive strength experiences a 47.9% increment, the cohesion increases by 83.18%, and the internal friction angle rises by 29.06%. In the simulation experiments addressing the saline-alkali-related pathologies of murals, compared to the untreated samples, the efflorescence height, efflorescence powder volume, and salt crust thickness of the samples treated by MICP (microbially induced calcite precipitation) decrease by 29.1%, 45.0%, and 36.4%, respectively. These findings accentuate the potential of B. oceanicus as an efficient and environmentally-friendly solution for the preservation of murals in saline-alkali settings, offering a fresh research perspective for cultural heritage conservation.

Ship energy consumption (SEC) efficiency optimization is crucial to sustainable maritime transportation. Due to commercial confidentiality, shipping data cannot be freely shared. Federated learning (FL) addresses this by predicting fuel consumption while maintaining data privacy. Traditional FL struggles with accuracy due to statistical heterogeneity in shipping data. To address it, an FL framework incorporating adaptive regularization terms is proposed. Alongside, given the scarcity of maritime communication resources, a tailored convolutional neural network-gated recurrent unit (CNN-GRU) model is designed for ship clients. Furthermore, based on the prediction results, a Mixed Integer Non-Linear Programming (MINLP) model is formulated to derive optimal speeds and establish a joint database for trim strategy output. Through the prediction and optimization approach, three optimized SEC efficiency metrics are obtained. Experimental results on data from eight bulk carriers show that the proposed FL framework with adaptive regularization terms improves prediction accuracy over individual, FedAvg, and FL with classical regularization term models. The CNN-GRU model outperforms IGWO-LSTM, GRU, and CNN-LSTM models in RMSE and adjusted R-squared value. The optimization approach enhances SEC efficiency by 1.42%-3.94%. These findings provide practical recommendations for maritime organizations to set efficient speeds and trim strategies for fleet management under secured data conditions.

Soil desertification and salinization are the main environmental disasters in arid and semi-arid areas. It is of great significance to study the water-salt migration law of saline soil and propose corresponding water-salt regulation and control measures. Microbial-induced calcite precipitation (MICP) technology was proposed to improve saline soil based on salt inhibition, and the water-salt-heat coupling migration law and salt-frost heave deformation law of saline soil before and after improvement were studied using soil column model tests. XR1#, XR2#(Saline-alkali-tolerant mineralization bacteria isolated from saline soil) and Sporosarcina pasteurii were used in the MICP improvement and the effect of XR1# was the best. Under high-temperature evaporation, the water migration change rate, water loss rate, accumulated evaporation amount, and accumulated salt content of the improved soil columns within a depth range of 0-40 cm were reduced by an average of 53.6 %, 47.3 %, 69.5 %, and 40 %, respectively, compared with the untreated soil column. During low-temperature cooling, the characteristics of water-salt migration changed significantly, and the deformation of salt-frost heave decreased significantly. The water-salt content at the freezing point (-4.5 degrees C) changed from a cliff-like steep drop (untreated saline soil) to a slow decrease at environmental temperature (MICP-treated saline soil), and the amount of water crystallization decreased from 81 % to 56.7 % at -5 degrees C. At the end of the cooling process, the amount of salt-frost heaving on the surface of the soil columns decreased by an average of 62.7 %. Based on the measured data, a numerical simulation was conducted using the HYDRUS-1D model, which had good reliability and accurately simulated and predicted the law of water-salt migration in saline soil under the conditions of microbial solidification and improvement. MICP technology significantly reduced the change rate of water-salt migration and water evaporation in saline soil, hindered salt accumulation, and reduced salt-frost heave deformation, which effectively improved saline soil. The research results provide an important innovation and theoretical basis for the improvement of saline soil.