Coarse-grained mixtures composed of coarse gravels and fine sands are widely used in subgrade constructions, coarse gravels of which contain rubbles and pebbles with different roundness (R_d). To investigate the effect of gravel shapes on the compaction behaviours of subgrades, the real-shaped gravel particles with varying R_d (0.2–0.5) were selected to establish coarse-grained mixtures models via the discrete element method (DEM). The contact parameters in DEM models were determined through a series of calibration tests, and the reliability of models was verified by vibration compaction tests with rubble-grained and pebble-grained mixtures. The evolutions of porosity, particle motion, and contact relationship affected by R_d were revealed from the macro-and mesoscales, and the influence of R_d on the stability of skeleton structures is discussed. As R_d decreases, the contact number tends to increase and the distribution of strong contacts is more uniform, the skeleton structure in which can effectively inhibit the motion of fine particles and the sliding between coarse particles. Conversely, the increase in R_d will cause the concentration of strong contacts, which further results in the sliding damage of skeleton structures and the improvement of compaction deformation.

Life cycle assessment (LCA) plays an increasingly important role in environmental management, particularly in promoting energy and carbon-conscious practices across various disciplines. This review provides an overview of the latest innovations and potential benefits of integrating LCA into ecological slope treatment strategies. This study explores new developments in LCA methodology and its application to slope treatment, aiming to improve the integration of infrastructure development and environmental stewardship. Through an extensive review of over 120 peer-reviewed journal articles and a critical analysis of the intersection of LCA with slope treatment, this paper identifies innovative techniques that have the potential to significantly reduce the environmental impact of slope management. The review emphasizes advanced LCA practices that quantify and mitigate carbon emissions throughout the life cycle stages of slope treatments. Key findings demonstrate that LCA enhances the methodological rigor in assessing ecosystem services and impacts, and reveals new strategies that emphasize the importance of ecological considerations in infrastructure projects. Future research directions focus on refining LCA data acquisition and promoting a standardized knowledge base to support precision in ecological impact assessments. In conclusion, the adoption of LCA in slope treatment is imperative for aligning industry practices with global sustainability targets, emphasizing the importance of integrating uncertainty analysis and long-term impact assessments to bolster the credibility of LCA outcomes.

Volcanic cinder is a low-cost subgrade fill material in East Africa. A reluctance to use volcanic cinders for subgrades in the past has stemmed from the compactness is substandard and variable. Considering the irregular shape of volcanic cinders, the compactness can be improved by controlling particle shapes. The shape feature can be described from the macro-meso-microscopic scales through the improved algorithms of shape indexes, namely elongation (EI), roundness (Rd), and roughness (Rg). The shape indexes were calculated based on 2D contours of 1000 volcanic cinder particles, and the influences of shape indexes on accumulation behaviors are explored from macro-mesoscales through the discrete element method (DEM). The shape indexes of volcanic cinders are normally distributed, and EI has the widest variation range. The mesoscale index Rd has an interval effect on compactness and coordination number, whereas are nearly unaffected by the microscale index Rg. The effect of elongation on particle accumulation behavior is stronger than roundness and roughness. Compactness is positively correlated with EI, and the force-fabric anisotropy degree weakens with increasing EI. Studies of shape quantification provide data reference for improving the utilization rate and accumulation compactness, which promotes the application of volcanic cinders in subgrade constructions.