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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, Numerical and experimental pseudo-static study on block arrangement effects in traditional dry-stone walls for out-of-plane mechanical behavior evaluation(Elsevier Ltd, 2024-12-01)In Lima's slopes, the absence of urban planning has led to housing built on backfills contained by traditional dry-stone retaining walls, called “pircas,” which pose high seismic risk. A previous study [1], which combined numerical and experimental analyses, evaluated pircas through pseudo-static tests that reflected common construction methods in Lima's eastern region. One recommendation from that study was to explore effective stone arrangements to enhance the seismic performance of pircas. Consequently, this study aims to examine how the construction process, particularly the arrangement of stones, impacts the out-of-plane behavior of pircas. The research focuses on identifying construction-feasible configurations that can effectively improve their seismic performance. For this purpose, natural-scale pseudo-static experimental studies and numerical modeling using the Discrete Element Method (DEM) were carried out. The experimental campaign consisted of nine pseudo-static tests on different wall arrangements. The pseudo-static numerical study included seventy wall arrangements. The geometry of the blocks was simplified to eliminate this component from the analysis, which focused on the arrangement of the wall. The numerical and experimental results showed the same trend. The study has demonstrated that the current construction technique can be significantly improved by regularly incorporating through-stones—tie stones that pass through the entire cross-section of the wall—and considering a cross-section with overlap. This approach leads to an increase of up to 50% in lateral strength compared to current practices, verifying the effectiveness of through-stones. The study does not intend to endorse the use of pirca for urban habitation in high seismic sectors. However, these traditional walls can be recommended for slope stability, environmental mitigation, urban agriculture, and protection of natural areas. - 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 Natural-Scale Specimens(Elsevier Ltd, 2023-08-01)On the slopes of some Andean cities, the population is at high seismic risk due to their informal homes, built without technical advice, based on non-compacted backfill, and supported by dry stone retaining walls (pircas). In this work, we aimed to evaluate the out-of-plane performance of the typical retaining walls of the city of Lima, Peru, located on the slopes of the central Andes. In this first study, the effect of the backfill has not been considered because only the behavior of the wall was studied. Three walls of height 1 m and three of height 1.5 m were built and tested. The construction was carried out by local workers, following their traditional practices, and tests were carried out on a tilting platform to generate out-of-plane gravity loads. Delamination and overturning were the most frequent types of failure. From the experimental tests, we found that the average ultimate resistance to displacement was 31 % and 24 % of the weight for the 1 m and 1.5 m walls, respectively. The discrete element method was used for the numerical models, and the contact parameters of stiffness and friction angle corresponding to the Coulomb model were calibrated using the experimental results. The effects on the mechanical behavior of the use of through stones and overlaps between wall elements were studied. It was concluded that the pircas could be improved to a limited extent with better construction practices, and further studies are therefore required with the aim of improving current construction practices. In a later study, the interaction between the wall and the backfill will be studied numerically and experimentally.