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Enhancing Spatial Interpolation: A Multi-Layer Inverse Distance Weighting Model for Complex Regression and Classification Tasks in Spatial Data Analysis
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Effects of small scaling on the stress dilatancy response of coarse gravel soil
Full text linkRÉSUMÉ: Dans la pratique, la caractérisation mécanique des matériaux graveleux est généralement réalisée sur des éprouvettes de petite taille, dans lesquels la dimension maximale des particules est réduite afin de permettre leur mise en place dans les appareils d’essai standard. Cette adaptation implique une modification de la granulométrie initiale, dont l’influence sur le comportement contrainte-déformation est bien connue. Toutefois, la majorité des études sur les effets de la granulométrie ont été menées après des essais sur des sables, et l’impact de la réduction d’échelle sur les sols graveleux reste encore marginalement compris. Cet article présente une étude expérimentale sur la réponse au cisaillement d’un sol grossier à différentes échelles d’éprouvettes. L’objectif principal est d’évaluer l’influence des méthodes de réduction d’échelle sur le comportement en déformation des sols grossiers. La technique de granulométrie tronquées a été utilisée pour préparer les éprouvettes. Des essais triaxiaux ont été réalisés à l’aide de cellules standards et de très grande taille, capables d'accommoder des éprouvettes de 100, 150 et 800 mm de diamètre. Les effets de la granulométrie et de la taille des éprouvettes sont présentés et discutés. Les analyses montrent que la dilatance diminue fortement avec la taille de l’éprouvette, tandis que la ligne d’état critique se déplace vers des indices des vides plus denses. Ces différences sont principalement liées à la granulométrie et aux propriétés de compacité —les éprouvettes réduites étant plus uniformément granulés que celles de grande taille. L’article présente des perspectives pratiques sur les effets liés à la réduction d’échelle et de leurs implications pour la caractérisation des matériaux graveleux. ABSTRACT: Stress strain behavior of oversized soils is usually assessed after tests on small-scale specimens, where grading is altered due to size restrictions imposed by the available testing devices. It is well known that particle size distribution (PSD) has a strong effect on the mechanical behavior of granular soils, however, most studies reported on this topic are related to sands. This study presents an experimental study of triaxial shearing on coarse soil at different size specimen scales. The scope is to evaluate the impact of small scaling through scalping grading on the stress strain behavior of coarse alluvial gravels. Conventional triaxial compression tests were performed on specimens of 100, 150 and 800 mm in diameter. Grading and size effects are presented and discussed. The results show that dilatancy strongly increases when reducing the specimen size, and the critical state line shifts to higher void ratios. This outcome is due to PSD and packing properties, because small scale specimens are more uniformly graded than coarser ones. The paper addresses the implications of small scaling in gravelly materials
Development and application of test cases for comparing vertical ground heat exchanger models
No full textBack-analysis of the geotechnical stability of high waste rock piles
Full text linkABSTRACT: Managing mine waste rock (WR) presents significant challenges due to its environmental impact and stability concerns. Typically, WRs are disposed of in piles using methods tailored to project specifications. The present paper is based on a large waste rock pile (WRP) built during the open-pit backfilling operation at the Canadian Malartic Mine. Backfilling is a cost-effective disposal method that minimizes the environmental impacts of mining operations. However, it often results in the formation of high WRPs that are prone to geotechnical instability during dumping and construction. Stability analyses of these structures often do not follow conventional geotechnical practices, since WR generated through blasting consists of coarse, angular grains, easily exceeding one metre in diameter, leading to considerable heterogeneity and variability in geotechnical properties within the piles. This adds significant uncertainty to conventional testing methods, resulting in potentially unreliable safety assessments. This paper examines the geotechnical stability of a high WRP using a multifaceted approach aimed at reducing these uncertainties. The method incorporates Finite Element modelling using the Hardening Soil constitutive model, with parameters calibrated after various triaxial laboratory tests, and considers the actual geometric configuration and construction sequence of the pile. The results have been validated through deformation monitoring data collected throughout all construction stages, to ensure short-term stability of the pile during truck dumping operations. Numerical modelling using 2D and 3D approaches revealed that, while shear strength was realistically captured, deformations were significantly overestimated due to limitations in laboratoryderived stiffness parameters. Back-analysis using recalibrated stiffness moduli improved alignment with field monitoring, suggesting current design guidelines may be conservative for WRPs in hard rock mines
