Current studies on soil tortuosity models typically assume a single particle size, neglecting the impact of particle gradation and spatial arrangement on pore channels and structures. To address this limitation, we develop a tortuosity model that incorporates multiple factors by assuming ellipsoidal particles and accounting for their arrangement and gradation. This model, combined with the Bingham fluid flow equation in porous media, elucidates the spherical penetration grouting mechanism of Bingham fluids, considering both tortuosity and time-varying viscosity. Using COMSOL Multiphysics, we simulate seepage to create a numerical program for Bingham fluid spherical seepage grouting that accounts for tortuosity and time-varying viscosity. Theoretical analysis and simulations validate our proposed tortuosity model and diffusion mechanisms. Additionally, we examine the sensitivity of the diffusion radius to Bingham grout rheology, grouting pressure, groundwater pressure, and grouting pipe radius. The research results demonstrate that the established tortuosity theoretical model is in excellent agreement with numerical simulations, with a maximum error of less than 3%. The spherical permeation grouting diffusion mechanism of Bingham fluid, which accounts for the tortuosity effect of porous media, more closely matches the experimental test values, achieving an average error of 10.13% and a minimum error of 3%. Grouting pressure and groundwater pressure are key factors, and their interaction with the grouting pipe radius has the strongest effect. These research findings provide valuable theoretical support for designing construction controls related to restoration projects involving porous medium earth-rock dams.

Accurate determination of potassium ion (K+) concentration in fingertip blood, soil pore water, pipette solution, and sweat is crucial for performing biological analysis, evaluating soil nutrients levels, ensuring experimental precision, and monitoring electrolyte balance. However, current electrochemical K+ sensors often require large sample volumes and oversized reference electrodes, which limits their applicability for the aforementioned small-volume samples. In this paper, a K+ sensor integrated with a glass capillary and a spiral reference electrode was proposed for detecting K+ concentrations in small-volume samples. A K+-selective membrane (K+-ISM)/ reduced graphene oxide-coated acupuncture needle (working electrode) was spirally wrapped with a chitosangraphene/AgCl-modified Ag wire (reference electrode). This assembly was then inserted into a glass capillary, forming an anisotropic diffusion region of an annular cylindrical gap with width 410 mu m and height 20 mm. It was found that the capillary action of the glass capillary results in a raised liquid level of the sample inside it compared to that in the container, which promotes efficient contact between the small-volume sample and the K+ sensor. Besides, the formed anisotropic diffusion region limits the K+ diffusion from the bulk solution to the K+ISM, which leads to a larger potentiometric response of the K+-ISM. The glass capillary-assembled K+ sensor displays high performance, including a sensitivity 58.3 mV/dec, a linear range 10_ 5-10_ 1 M, and a detection limit 1.26 x 10_6 M. Moreover, it reliably determines K+ concentrations in artificial sweat of microliter volume. These results facilitate accurate detection of K+ concentration in fingertip blood, soil pore water, and pipette solution.

Although significant theoretical and technological advancements have been made in the application of concrete in saline soil regions over the past two decades, newly constructed reinforced concrete structures in these areas still face severe issues of corrosion and degradation. This is due to the complex deterioration environment in saline soil regions, characterized by the combined effects of salt corrosion, dry-wet cycles, and freeze-thaw conditions. The reduced service life of concrete structures in this region is closely related to the diffusion and distribution patterns of high-concentration chloride salts and various corrosive ions within the concrete. These patterns affect the content, transformation, and microstructure of corrosion products, ultimately leading to a shorter service life compared to other environments. This paper simulates the saline-alkali soil environment using solutions of different concentrations of chloride sulfates and magnesium salts, studies the diffusion and distribution patterns of chloride ions and sulfate ions in concrete under this environment, and analyzes the mechanism of action in conjunction with changes in microstructure. The experimental system adopts a dry-wet cycle test that can represent the characteristics of the semi-arid continental climate in Western China. The results show that although the content of free chloride ions and total chloride ions entering the concrete in the saline-alkali soil simulation solution is the lowest, the binding capacity of chloride ions is significantly greater than that of sulfate ions and far exceeds that in other environments. Under the action of high-concentration chlorides alone, the content of chloride ions in concrete is the highest, and the binding capacity of chloride ions also increases with the concentration of chlorides. The content of free sulfate ions and total sulfate ions entering the concrete in the saline-alkali soil simulation solution and their binding capacity are higher than in the control solution. Due to the ability of sulfate ions to hinder the diffusion of chloride ions in concrete, magnesium ions play a hindering role in the early stage and an accelerating role in the later stage. This results in concrete corroded by the saline-alkali soil environment, which has a characteristic of low chloride ion content and high sulfate ion content. The ions in the saline-alkali soil solution that cause concrete damage are Cl-, SO42-, and Mg2+. These ions react with the concrete to form Friedel's salt, Aft and AFm phase calcium aluminate, gypsum, Mg-S-H, and Mg(OH)2, among other substances. These corrosion products significantly impact the microstructure of concrete, causing the microstructure of concrete to transition from dense to loose to cracked much earlier than in other environments.

In comparison with plant fibers, wool is under-exploited in composite applications. Coarse wool with >50 micron diameter is generally not preferred for apparel, blankets, or carpets and remains underutilized. In the reported work, non-textile grade coarse wool fabric was coated with vinyl ester resin (VER), and subsequently, composites were developed. To increase the mechanical properties of the composite, nano kaolinite was introduced as a filler. The effect of various concentrations (0.25, 0.50, 1.0 %) of nano kaolinite (NK) on the physico-mechanical and aging characteristics of the developed composites was investigated. The results inferred that a minor addition of nano kaolinite (0.5%) in the wool + VER composite resulted in an increase of 16% tensile strength, 31% modulus, and 19 % impact strength, respectively. The findings of the dynamic mechanical analysis showed that, with 0.5% nano kaolinite addition, the composite's storage and loss modulus were exhibited as 1.9 and 0.22 GPa, respectively, which are higher than those of the control wool + VER composites (1.1 and 0.15 GPa storage and loss modulus respectively). The SEM images depicted a moderate adhesion between the wool fiber and the vinyl ester resin. The presence of nano kaolinite in the composite results in a marginal reduction in the water contact angle and an increase in the water diffusion properties. The thermal and UV aging properties of the wool-vinyl ester composites were improved with the addition of nano kaolinite; however, the developed composites showed poor soil degradation.

This study introduces a unified cylindrical and spherical cavity reverse expansion model to simulate the formation of compaction grouting bodies and grout diffusion along pile shafts. Stress field expression employs the superposition method, while displacement field analysis utilizes the nonassociated Mohr-Coulomb criterion. By combining the displacement expression for cylindrical cavity reverse expansion with the fluid flow equation, a calculation method is proposed to compute the upward and downward diffusion heights of grout, considering the unloading effect. The parameter analysis demonstrates that ultimate grouting pressure increases with increasing soil strength and grouting depth, with the ultimate grouting pressure at the pile tip being greater than that at the pile side. The value of grout diffusion height is negatively correlated with unloading ratio and grouting depth while positively correlated with grouting pressure and pile diameter. The deeper the grouting depth, the greater the impact of unloading on grout diffusion height. Three case studies validate the effectiveness of the proposed model. Analysis reveals that when grouting pressure exceeds the ultimate pressure, the size of the grout body is related to the grouting volume. Neglecting the unloading effect in the prediction of grout diffusion height for pile foundations would lead to conservative results.

In this study, advanced image processing technology is used to analyze the three-dimensional sand composite image, and the topography features of sand particles are successfully extracted and saved as high-quality image files. These image files were then trained using the latent diffusion model (LDM) to generate a large number of sand particles with real morphology, which were then applied to numerical studies. The effects of particle morphology on the macroscopic mechanical behavior and microscopic energy evolution of sand under complex stress paths were studied in detail, combined with the circular and elliptical particles widely used in current tests. The results show that with the increase of the irregularity of the sample shape, the cycle period and radius of the closed circle formed by the partial strain curve gradually decrease, and the center of the circle gradually shifts. In addition, the volume strain and liquefaction strength of sand samples increase with the increase of particle shape irregularity. It is particularly noteworthy that obvious vortex structures exist in the positions near the center where deformation is severe in the samples of circular and elliptical particles. However, such structures are difficult to be directly observed in sample with irregular particles. This phenomenon reveals the influence of particle morphology on the complexity of the mechanical behavior of sand, providing us with new insights into the understanding of the response mechanism of sand soil under complex stress conditions. (c) 2024 Chinese Society of Particuology and Institute of Process Engineering, Chinese Academy of Sciences. Published by Elsevier B.V. All rights are reserved, including those for text and data mining, AI training, and similar technologies.

In this article, a one-dimensional non-isothermal diffusion model for organic pollutant in an unsaturated composite liner (comprising a geomembrane and an unsaturated compacted clay liner (CCL)) considering the degradation effect is established, which also includes the impacts of temperature on diffusion-related parameters, and employs a water content and pore-water pressure head relationship equation that better matches the experimental results. Subsequently, this model is addressed through a finite-difference technique, and its reasonableness is proved by comparing with the experiment measurements and two other calculation approaches. Following this, the analyses suggest that the diffusion coefficients' change induced by a rising temperature accelerates the diffusion rate, whereas such an alteration on partitioning coefficients has an opposite effect. Furthermore, the evaluation reveals that the non-isothermal state caused by an increasing upper temperature overall lowers the anti-fouling performance. The unsaturated composite liner's barrier function is weakened by an increment in residual water content of CCL, but enhanced by unsaturated layer thickness. It is also detected that the degradation effect should be considered if the degradation half-life <= 100 years. Lastly, a simplified approach for assessing the unsaturated composite liner's barrier performance is presented, which can provide guidance for its engineering design in a non-isothermal scenario.

Due to the considerable variation in the range of rock content of the soil-rock mixture, when grouting experiments were conducted according to the existing grouting theory, it was found that a large number of pores not entirely filled by the slurry existed in the concretions of the medium to high rock content backfill area. Therefore, the existing slurry permeation grouting diffusion equation was optimized by adding the filling factor (gamma). Based on the Bingham fluid rheological equation and the Newtonian fluid rheological equation, the optimized calculation equations for Bingham fluid and Newtonian fluid permeation diffusion considering the filling factor (gamma) were derived. Furthermore, the indoor grouting experiment data are compared and analyzed with the calculation results of the original formula and the optimized formula. The results show that when ignoring the unfilled pores, the original formula calculating the diffusion radius will be small; the calculation results of the optimized formula considering the filling factor (gamma) are closer to the actual experiment results. Moreover, based on the calculation results of the optimized formula, the order of influencing factors of the permeation diffusion radius is rock content > void ratio > water-cement ratio > grouting pressure.

The failure of fractured rock masses in slopes due to freeze-thaw processes is a common occurrence in cold regions, leading to significant issues such as soil erosion and landslide disasters, particularly in mining areas. This study utilizes a self-developed true triaxial grouting apparatus to perform full-stress state grouting on freeze-thawed fractured rock. Furthermore, a computational simulation of CT permeability is conducted on the rock mass post-grouting. The primary focus of this research is the quantitative assessment of the waterproofing properties of grout masses utilizing microsilica powder-enhanced cement, along with an analysis of freeze-thaw durability at the grout-rock interface. Experimental findings indicate that microsilica facilitates particle aggregation through nucleation effects and expedites cement hydration via pozzolanic reaction, thereby significantly improving the impermeability and frost resistance of the interface transition zone. Compared to ordinary Portland cement (PC) grouting for waterproofing, the anti-seepage rate is increased by 17% and 20% when microsilica cement is used to grout rock masses that have undergone freeze-thaw cycles of 25 and 45, respectively. The outcomes of this investigation hold substantial importance in enhancing the grouting reinforcement mechanisms of fractured rock masses in cold regions and in implementing targeted preventive and control strategies. Grouting in a freeze-thaw rock mass under a true triaxial state.CT reconstruction of the grouting vein and seepage simulation.Microsilica enhancement of the compactness and freeze-thaw damage resistance of the grout-rock interfacial transition zone.

The study is concerned with the rate of evaporation from porous rock, including the second stage of evaporation characterised by the existence of a dry surface layer separated from the wet capillary zone by a sharp evaporation front. The main objective is to investigate the relationship between the depth of evaporation front and the rate of evaporation as the drying process progresses, and to compare measured evaporation rate with the corresponding calculated values. Sandstone core samples saturated with water were allowed to dry naturally under room conditions, while the changes in the evaporation rate and the depth of evaporation front, among other quantities, were measured. We demonstrate that the evaporation rate can be very accurately determined from the depth of the evaporation front and the ambient air temperature and relative humidity using Fick's law for water-vapor diffusion. During the second stage of evaporation, the diffusion flux through the dry surface layer is computed using the water-vapor diffusion coefficient of the rock, determined from a separate wet cup experiment. In order to cover the first stage of evaporation, an additional parameter characterising the diffusion layer of air above the surface is required, either determined by the best fit to the measured evaporation rates, or adopted from previous studies. The calculated evaporation rate was in good agreement with measurements, with Pearson correlation coefficient 0.98 and relative error of the calculations averaging 15% over the evaporation front depths ranging from 0 to 29 mm. A workflow for determining the evaporation rate from sandstone outcrops is suggested, along with possible applications in sandstone weathering research.