Yang Zheng

Depth gradients, which arise from variations in geostress at different strata, lead to rapid alterations in the internal stress state of rocks during blasting operations. These changes contribute to heterogeneities in rock strength and blast resistance, thereby presenting potential risks to engineering safety. To understand the damage and fracture patterns typically observed in granite blasting activities within underground engineering projects, we created a series of rectangular six-hole models using the advanced finite element software ABAQUS. By utilizing the Coupled Eulerian–Lagrangian (CEL) technique, the model distinguished between Eulerian parts, segmented into domains, and Lagrangian elements; the Eulerian domain was designated as air, while the Lagrangian section was characterized by TNT to mimic the shock wave propagation following detonation. This research scrutinizes the geostress conditions of granite across varying depth gradients, elucidates the extent and severity of granite impairment induced by blasting, and furnishes innovative viewpoints and methodologies for examining rock damage mechanisms in blasting engineering.

Gear provides an important means of transmission in the automobile, and the service life of the gear teeth has a direct effect on how the engine performs. To enhance the strengthening performance of gear surface, three composite coatings were prepared in this paper by supersonic flame spraying technology, with nickel-based powder as the main material, and ceramic powder WC, TiO2 and Cr3C2 added to it respectively. Hardness tester, scanning electron microscope, X-ray diffractometer and other devices were used to comparatively evaluate the performance of the coatings. Then, static simulation was carried out for the coating. The results show that the coating containing Cr3C2 is superior to the other two coatings in densification and hardness. Finally, ANSYS software was applied to model the gear surface coating, revealing that the gear with Cr3C2 ceramic powder is advantageous over the coating with TiO2 particles.

Marine soft clay is characterized by a high water content and low strength, exhibiting pronounced creep deformation under long-term loading that threatens the serviceability and durability of coastal infrastructure. Accordingly, this study develops a creep constitutive model that combines elastic, plastic, and viscous effects and quantitatively evaluates time-dependent deformation under varying water contents and stress levels to provide reliable prediction tools for tunnel, excavation, and pile-foundation design. Cyclic creep tests were carried out on reconstituted marine soft clay with water contents of 40–60% and stress ratios of 0.4–1.2 using a pneumatic, fully digital, closed-loop triaxial apparatus. A “nonlinear spring–Bingham slider–dual viscous dashpot in parallel with a standard Kelvin dashpot” element assembly was proposed, and the complete stress–strain relationship was derived. Experimental data were fitted with Python to generate a creep-strain polynomial and verify the model accuracy. The predicted–measured creep difference remained within 10%, and the surface-fit coefficient of determination reached R² = 0.97, enabling rapid estimation of deformation for the given stress and time conditions. The findings offer an effective method for the precise long-term settlement prediction of marine soft clay and significantly enhance the reliability of the deformation assessments in coastal civil-engineering projects.

The study of energy evolution laws has been widely applied in the geotechnical analysis of soft rocks and coal seams. However, research on marine soft soil has primarily focused on consolidation behavior, shear properties, and microstructural evolution, with limited exploration of systematic methods based on energy evolution laws. This paper addresses this gap by analyzing dynamic triaxial test data to explore the relationship between energy loss rate and the number of cyclic loadings in marine soft soil. Through energy loss calculations and derivations, a mathematical expression for the energy loss rate is established using curve fitting. Additionally, an envelope diagram depicting the energy dissipation rate of marine soft soil under varying perimeter pressures and water contents is presented. This diagram serves as a criterion for assessing the stability of marine soft soil, which is further validated through engineering applications. The findings offer novel approaches and insights for developing theoretical models and rapid strength assessment techniques for marine soft soil in engineering practices.