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Item type:Publication, Out-of-plane analysis of dry-stone walls using a pseudo-static experimental and numerical approach in scaled-down specimens(Elsevier, 2021)The objective of the present work is to study the response of dry stone walls subjected to out-of-plane forces and the influence of block`s rugosity, joint arrangement, and border conditions. For this purpose, a series of scaled-down experimental tests on a tilting table and 3D numerical modelling using discrete elements, DEM, are proposed. In the numerical model, the applicability of some types of discrete elements is first studied. The preliminary analysis gives us useful information about the effects of the joint disposition and the border conditions in the response. Finally, the sensitivity of the response of the blocks to the parameter’s variations is analyzed. The experimental and numerical results show that the DEM method is adequate to simulate the failure mode, the displacement, and the lateral load of stone walls due to out-of-plane lateral loads considering the effect of the irregularity of the blocks, joint arrangement, and border conditions. - Some of the metrics are blocked by yourconsent settings
Item type:Publication, Out-of-plane analysis of dry-stone walls using a pseudo-static experimental and numerical approach in scaled-down specimens(Elsevier, 2021-10-15)The objective of the present work is to study the response of dry stone walls subjected to out-of-plane forces and the influence of block‘s rugosity, joint arrangement, and border conditions. For this purpose, a series of scaled-down experimental tests on a tilting table and 3D numerical modeling using discrete elements, DEM, are proposed. In the numerical model, the applicability of some types of discrete elements is first studied. The preliminary analysis gives us useful information about the effects of the joint disposition and the border conditions in the response. Finally, the sensitivity of the response of the blocks to the parameter's variations is analyzed. The experimental and numerical results show that the DEM method is adequate to simulate the failure mode, the displacement, and the lateral load of stone walls due to out-of-plane lateral loads considering the effect of the irregularity of the blocks, joint arrangement, and border conditions. - Some of the metrics are blocked by yourconsent settings
Item type:Publication, Dynamic numerical study of traditional dry-stone walls with YADE(Springer Science and Business Media B.V., 2024-01-01)On the hills of some Andean cities in South America, the population has built their homes on terraces supported by traditional dry-stone retaining walls (“pircas”) without any regulation or code. Because this zone is prone to strong earthquake ground motions, it is necessary a better understanding of the pircas’s out-of-plane behavior and collapse mechanism for risk prevention and mitigation. However, no dynamic studies of this traditional construction exist to date. This work addresses a numerical study of the response of pircas subjected to ground motions in the out-of-plane direction and how different construction techniques (i.e. block arrangements and wall configurations) can affect this response. The dynamic analysis was carried out with the YADE (open-source software for discrete numerical models and focused on the Discrete Element Method, DEM). By varying the vertical separation of Through stones (tie stones) and overlap of stones in the cross-section of the walls, we obtained 5 models which were subjected to a representative seismic signal. Regular and parallelepiped clumps (groups of rigidly joined spheres) were selected for modeling the wall blocks due to their versatility in their geometry and lower computational cost than other types of particles supported by YADE [1]. The effect of the backfill has not been considered yet, since we are focused on the wall configuration effects on the dynamic response. In the absence of dynamic experimental results, the precise calibration of the numerical model has yet to be sought. The results obtained are preliminary. At a later stage, an experimental dynamic test will be carried out, and they can be properly calibrated. The numerical results showed that when the wall presents a cross-section with adequate overlap, the amount of Through Stone (from 2.2 to 3.6 per m2) is not important. On the other hand, when the wall cross-section has no overlap, the wall presents the least resistance to moderate damage levels and collapse. Additionally, it was possible to verify that the pseudo-static out-of-plane response (obtained in a previous study) is more conservative than the dynamic one. - Some of the metrics are blocked by yourconsent settings
Item type:Publication, Qualitative and quantitative analyses of particulate flows in rotating drums using a DEM-based approach(Springer Science and Business Media Deutschland GmbH, 2024-10-01)In mineral processing, ore grinding is an energy-intensive process. Tumbling mills used in grinding processes can be accounted for as rotating drums with liners. As part of an effort to evaluate ways of reducing energy consumption in such systems, therefore, particulate flows in rotating drums are studied in this work. More specifically, using a new DEM tool, which is one of the modules of a larger in-house computational package called CFLOWSS, particulate flows in rotating drums are qualitatively and quantitatively analyzed. The results from such analyses are compared with experimental ones and other numerical results obtained using a commercial DEM software. In qualitative terms, the CFLOWSS results show a relatively good agreement with experimental photographs previously taken in a laboratory. In quantitative terms, in turn, the CFLOWSS predictions show a strong correspondence with those ones made by the commercial software. For instance, the relative discrepancies of the boxplots’ medians associated with the number of contacts, power, and forces predicted by both (in-house and commercial) tools present values smaller than 8%. At a 60 RPM drum rotation velocity, indeed, the number of contacts related discrepancies reach values as low as 0.8%. Some of the contributions of this work involve (i) the development of a new DEM tool capable of realistically describing particulate flows in rotating drums, and (ii) the use of statistical treatments to quantitatively analyze DEM results. This last aspect is important because this sort of assessments provides an improved way to analyze the behavior of particulate flows. - Some of the metrics are blocked by yourconsent settings
Item type:Publication, Identification of Morphostructures by Utilizing Knickpoint Ranks, a Method to Avoid the Camouflage Effect in Knickpoint Analysis(Elsevier B.V., 2023-12-01)Knickpoints are relief features characterized by a convex-up abrupt change in the equilibrium profile of a given river. In the field they can be recognized as rapids or waterfalls. Their presence indicate geological conditions or processes that modify erosive rates, such as contrasting lithologies, base-level changes, or active structures, and, therefore, especially relevant in tectonic geomorphology studies. The computation of knickpoints for classification purposes is made dividing the Slope-Extension Ratio (RDE) by the Total Slope-Extension Ratio (RDT), which are derived from the Stream-Gradient index (SL). Traditionally, the classification of knickpoints has been treated in two ways, (1) by the simple division into first and second order, according to a limit value of RDE/RDT of 10, and (2) by the statistical division of values into classes, mainly with natural breaks. Recent studies have used both divisions and correlated the RDE/RDT values with the size of the knickpoints in the field. However, there are studies on morphometric analysis that point to the existence of gaps that occur in specific cases, such as the so-called knickpoint camouflage. In order to eliminate these gaps and with the aim of improve the classification technique, we propose the determination of fixed intervals of distribution of knickpoints which, based on the division according to the RDE/RDT values, use the strengths of the statistical divisions as a means to define limits of RDE/RDT values. The objective of this methodological development is to prevent errors during the classifications as well as to facilitate the interpretation of the obtained knickpoints. The new classification method was applied in 20 hydrographic basins with their RDE/RDT values checked in 44 knickpoints in the field. The analyses carried out point to the coherence of the new proposed classification and confirm the effectiveness of both the fixed intervals and the tools used in the cartography of knickpoints.