The existence of dispersive clay soils can cause serious erosion, void, and structural damage due to an imbalance of the electrochemical forces within the particles, which causes the soil particles to be repulsive instead of being attracted to each other. Dispersivity is observed in several highway embankments in Mississippi, and the embankments have eroded and developed voids over time. The current study investigated the root cause of the voids observed within the subgrade of the state highway 477 in Mississippi and evaluated the dispersivity of high cations-based soil. As part of an investigative initiative, a 2D Ground Penetration Radar (GPR) of the highway embankment road to make a 2D profile of the soil subsurface media was surveyed to reveal that potential hotspots were overlooked, leading to suspected soil dispersivity and subsequent issues. To assess the extent of visible voids and sinkholes, dispersive tests, including the Double Hydrometer Test (DHT), were conducted to evaluate the dispersivity of the clay soils. A series of boreholes were drilled along the roadway to collect the soil samples, determine their physical properties, and identify clay soil dispersity within the soil profile. Following the confirmation of dispersive soil existence through these tests, advanced analyses, such as Scanning Electron Microscope (SEM) to identify the microstructures and the ionic compositions of the soil particles and Toxicity Characteristic Leaching Procedure Tests (TCLPT) to assess the solubility of high concentrated elements in liquid, were performed to comprehend the root cause of the soil dispersion. Based on the results of the analysis, the GPR wave cannot pass through the subgrade, which mostly happens due to the presence of the charge within the soil. Based on SEM, DHT, and TCLP test results, the soil samples have high cations, including the presence of K + . Moreover, a similar distribution of the ionic compositions was observed among the majority of the soil samples; however, the percent of dispersion regarding clay soil particles varied.

The deformation characteristics of silty soils under vibrational loads can easily change due to the wetting process, leading to the failure of roadbed structures. Commonly used methods for improving silty soils in engineering often yield unsatisfactory economic and ecological outcomes. As an environment-friendly soil improvement material, Xanthan gum has broad application prospects and is therefore considered a solidifying agent for enhancing silty soil properties in the Yellow River Basin. In this study, a series of tests is conducted using a scanning electron microscope and a dynamic triaxial testing apparatus to investigate the microstructure and dynamic deformation characteristics of unsaturated silty soil with varying xanthan gum contents during the wetting process. The results show that xanthan gum effectively fills voids between soil particles and adheres to their surfaces, forming fibrous and network structures. This modification enhances the inherent properties of the silty soil and significantly improves its stability under dynamic loading. Specifically, with increasing xanthan gum content, the dynamic shear modulus increases while the damping ratio decreases. During the wetting process, as suction decreases, the dynamic shear modulus decreases while the damping ratio increases. Xanthan gum reduces the sensitivity of the dynamic deformation characteristics of the treated silty soil to changes in suction levels. Finally, based on the modified Hardin-Drnevich hyperbolic model, a predictive model for the dynamic shear modulus and damping ratio of treated silty soil is proposed, considering the xanthan gum content. These research findings provide a theoretical basis for the construction and maintenance of water conservancy, slope stabilization, and roadbed projects in the Yellow River Basin. (c) 2025 Institute of Rock and Soil Mechanics, Chinese Academy of Sciences. Published by Elsevier B.V. This is an open access article under the CC BY-NC-ND license (http://creativecommons.org/licenses/by-nc-nd/ 4.0/).

The paper presents the method of photogrammetric processing of SEM images and the results of its application to determine the spatial coordinates of the points of the microsoil of the forest soil by measuring their SEM images, obtained on SEM Hitachi S800 with a magnification of 1000x. Depending on the magnification (scale) of the SEM images, the accuracy of the method is: for M = 1000x - m(X,Y) = similar to 0.1 mu m, m(Z(h))= similar to 1.0 mu m, and for magnification M = 25000x - m(X,Y) = similar to 0.01 mu m, m(Z(h))= similar to 0.1 mu m. The article presents an unusual workflow based on processing in Dimicros, as well as examples of graphic interpretation of digital modeling of the forest soil surface microrelief in the form of microplanes with levels and 3D models obtained using the Surfer program. This information allows learning about the physical and mechanical properties of the soil, its structure, and its resistance to erosion, which is important in construction and environmental protection.

Porosity is an important parameter that affects the deformation, mechanical properties, and constitutive relationships of soil structures. It can be used as an important basis for deterioration research and safety assessment in the field of earth site protection. By collecting scanning electron microscope images (SEM) of the rammed earth of the ancient city wall of Pingyao, a world cultural heritage, and using software such as ImageJ and MATLAB to analyze the characteristics of the images from two-dimensional and three-dimensional perspectives, the relationship between threshold and porosity was studied and summarized. It was found that using the Boltzmann function eigenvalue as the control threshold can well characterize the two-dimensional porosity of soil. Using the idea of integration, the binary slice images with different thresholds are simplified and accumulated to construct a three-dimensional image porosity calculation model. Write a three-dimensional pore characteristic parameter program to extract the statistical image grayscale information and perform normal fitting. Based on the probability interval of the image grayscale distribution, calculate the threshold interval that can effectively reflect the three-dimensional pore characteristics of the soil. This research has important theoretical and practical significance for the protection research of earthen sites. The study of image-based porosity calculation can provide an important basis for the study, conservation and evaluation of earthen artifacts.A calculation model of image three-dimensional porosity is proposed.A calculation method that can effectively reflect the three-dimensional pore structure characteristics of soil is proposed.Use mathematical principles to construct the relationship between microscopic image porosity and macroscopic porosity.

Due to the inhomogeneity and anisotropy of mine rock bodies, ionic rare earth ore bodies exhibit varying pore structures at different depths. This research focuses on an ionic rare earth mine in Fujian Province, where in situ ore samples rather than remodeled soil samples were studied. Samples from the fully weathered layer at depths of 1 m, 12 m, and 21 m, both before and after leaching, were collected for onsite analysis. Microscopic pore characteristics were evaluated using scanning electron microscopy, and digital image processing was utilized to study the evolution of the pore scale, distribution, and shape in rare earth ore samples at various depths pre- and post-leaching. The results indicate an increase in the ore body's porosity with the depth of the ore samples both before and after leaching. The variation in pore scale is predominantly dictated by the ratio of macropore and large pores. Pre-leaching, the middle ore sample showcased the highest uniformity, with the upper part being the most irregular. Post-leaching, the highest uniformity was observed in the lower ore samples, with the upper part remaining irregular. Pre-leaching, as depth increased, the pore distribution in ore samples became more dispersed, with decreasing orderliness. Post-leaching, the orderliness was most improved in upper ore samples, while middle ore samples became the least orderly. Additionally, before leaching, pore-shape roughness increased with depth; after leaching, the pore shape became more rounded as depth increased, simplifying the pore-shape structure of the ore samples both before and after leaching.

The behavior of granular soils is intricately linked to their origin and sedimentation mechanisms, as evidenced by their unique morphological characteristics shaped by depositional environments. This study investigates into the critical relationship between these morphological attributes, including sphericity, angularity, and roundness, and the mechanical properties of granular soils. Such understanding is pivotal for applications like piled foundations, large dam filters, and pavements in geotechnical engineering. To assess this relationship, three granular soils from distinct depositional environments were selected, and their morphological features were meticulously examined using scanning electron microscopy (SEM) and analyzed using ImageJ software. Additionally, surface roughness parameters were quantified through an optical profilometer. The mechanical response of these soils was comprehensively investigated through direct shear tests, with a specific focus on the impact of shape factors. The results of this study unveiled striking differences between river sand deposits and coastal sand in terms of morphological attributes. River sand exhibited higher angularity, reduced roundness, and a greater number of surface asperities, contributing to heightened frictional resistance and pronounced dilatancy effects when subjected to shear loads. This paper underscores the significance of morphological features in influencing the macroscale properties of granular soils and provides valuable insights for geotechnical engineering applications.