This study introduces a novel, interdisciplinary method that merges fundamental geomechanics with computer vision to develop an advanced hybrid feature-aided Digital Volume Correlation (DVC) technique. This technique is specifically engineered to measure and compute the full-field strain distribution in fine-grained soil mixtures. A clay-sand mixture specimen composed of quartz sand particles and kaolinite was created. Its mechanical properties and deformation behaviour were then tested using a mini-triaxial apparatus, combined with micro-focus X-ray Computed Tomography (mu CT). The CT slices underwent image processing for denoising, segmentation of distinct phases, reconstruction of sand particles, and feature extraction within the soil specimen. The proposed approach incorporated a two-step particle tracking method, which initially uses particle volume and surface area features to establish a preliminary matching list for a reference particle and then use the Iterative Closest Point (ICP) method for precise target particle matching. The soil specimen's initial displacement field was then mapped onto the DVC method's grid, and further refined through subvoxel registration via a three-dimensional inverse compositional Gauss-Newton algorithm. The proposed method's effectiveness and efficiency were validated by accurately calculating the displacement and strain fields of the soil mixture sample, and comparing the results with those from a traditional DVC method. Given the soil's compositional and microstructural characteristics, these image-matching techniques can be integrated to create a versatile, efficient, and robust DVC system, suitable for a variety of soil mixture types.

In an effort to enhance engineering infrastructure and reduce environmental waste, the use of COVID-19 face-mask chips (FMC) in sand reinforcement is experimentally explored through drained hollow cylinder torsional shear tests, including monotonic stress paths with different fixed orientation of the principal stress axes and cyclic tests with traffic load and pure principal stress rotation. Fujian sand and Hong Kong CDG sand were used. The monotonic test results indicate that both sands exhibit a strong strength anisotropy, however, although the addition of FMC increases the peak stress ratio to failure of the composites for all tests, the strength anisotropy trends with alpha(sigma) are not changed. Results from x-Ray CT scanning analyses conducted on FMC-reinforced and unreinforced cylinder sand specimens supported the interpretation of experimental data. Furthermore, the inclusion of FMC induces increased plastic deformation under cyclic loads in all tests, however, the level of these plastic strains is sand-type and stress-level dependent. It was also observed that both sands exhibit non-coaxial characteristics, but the presence of FMC inclusions do not change the non-coaxial trends observed for the pure sands.

Environmental vibrations produced often by industrial and construction processes can affect adjacent soils and structures, sometimes resulting in foundation failure and structural damage. The application of confined cells under foundations as a mitigation technique against dynamic sources, such as generators, is investigated in this study. Numerical models were developed using Plaxis 3D software to simulate the effect of a vibrating source on a circular footing, both with and without confined cells filled with sand soil at varying depths and diameters. In these cells, the soil modeling considered compaction loads typical in actual construction conditions. Results indicate that placing a minimum-diameter cell closer to the foundation with adequate penetration depth can significantly enhance dynamic response and reduce subgrade deformation. The effectiveness of confined soil in minimizing displacement amplitude in the foundation is evaluated, revealing an impressive 86% reduction with specific cell dimensions (Hc/D = 0.50 and Dc/D = 1.15). Moreover, peak particle velocity and excess pore water pressure at monitored points in the surrounding environment experience reductions of 62% and 87%, respectively, demonstrating substantial vibration attenuation. The study does effectively highlight the novelty of the confined sand cell approach, positioning it as a more targeted, efficient, and cost-effective alternative to existing methods, especially for conditions where large-scale, deep vibrations are a concern.

Under traffic load, earthquake load, and wave load, saturated sand foundation is prone to liquefaction, and foundation reinforcement is the key measure to improve its stability and liquefaction resistance. Traditional foundation treatment methods have many problems, such as high cost, long construction period, and environmental pollution. As a new solidification method, enzyme-induced calcium carbonate precipitation (EICP) technology has the advantages of economy, environmental protection, and durability. Through a triaxial consolidated undrained shear test under cyclic loading, the impacts of confining pressure (sigma 3), cementation number (Pc), cyclic stress ratio (CSR), initial dry density (rho d), and vibration frequency (f) on the development law of pore water pressure of EICP-solidified sand are analyzed and then a pore water pressure model suitable for EICP-solidified sand is established. The result shows that as sigma 3 and CSR increase, the rise rate of pore water pressure of solidified sand gradually accelerates, and with a lower vibration number required for liquefaction, the anti-liquefaction ability of solidified sand gradually weakens. However, as Pc, rho d, and f rise, the increase rate of pore water pressure of solidified sand gradually lowers, the vibration number required for liquefaction increases correspondingly, and its liquefaction resistance gradually increases. The test results are highly consistent with the predictive results, which show that the three-parameter unified pore water pressure model is suitable for describing the development law of A-type and B-type pore water pressure of EICP-solidified sand at the same time. The study results provide essential reference value and scientific significance in guidance for preventing sand foundations from liquefying.

A bacterial strain, designated GEM5(T), was isolated from sand soil samples from the Qinghai-Tibet Plateau. The polyphasic study confirmed the affiliation of the isolate with the genus Massilia. GEM5(T) had Gram-stain-negative, non-spore-forming and rod-shaped cells and grew at 4-30 degrees C. pH 6-8 and with 0-2% (w/v) NaCl. Its cell wall contained ribose. Q8 was the predominant respiratory quinone, and summed feature 3 (C-1(6:1), omega 6c/w7c) and C-16:0 were the major components of the fatty acids. The polar lipids were diphosphatidylglycerol, phosphatidylethanolamine, phosphatidylglycerol, an unidentified phospholipid, an unidentified aminolipid and four unidentified lipids. The DNA G+C content was 65.1 mol%. The phylogenetic analysis based on the 16S rRNA gene showed a stable Glade being formed by GEM5(T), Massilia timonae CCUG 45783(T) (97.94%) and Massilia oculi CCUG 43427A(T) (97.58%). The average nucleotide identity (ANIb) values between GEM5(T) and M. timonae CCUG 45783(T), M.oculi CCUG 43427A(T) were 91.3 and 91.7%, respectively. On the basis of the morphological, physiological and chemotaxonomic pattern, it was proposed that strain GEM5(T) (=JCM 32744(T)=CICC 24458(T)) should be classified as representing a member of the genus Massilia with the name Massilia arenae sp. nov.