http://localhost:8080/xmlui/handle/123456789/53 Mon, 13 Apr 2026 15:27:53 GMT 2026-04-13T15:27:53Z http://localhost:8080/jspui/retrieve/7da9644e-9fe8-4f5f-9958-518b54976e37/Hydraulique-removebg-preview.png http://localhost:8080/xmlui/handle/123456789/53 http://localhost:8080/xmlui/handle/123456789/2293 Titre: Etude de l’influence des sous-pressions par fissuration hydraulique dans un barrage-poids en béton compacté au rouleau (BCR) Auteur(s): Hichem, Mazighi Résumé: La stabilité d'un barrage en béton est d'une importance cruciale pour la sécurité des populations vivant en aval du barrage, elle est un aspect complexe de l'ingénierie hydraulique, et elle nécessite une planification, une conception, une construction et une surveillance. Cela a fait l'objet de nombreuses études visant à améliorer les méthodes de calcul de stabilité et à évaluer les propriétés mécaniques et hydromécaniques des ouvrages pour garantir que les barrages en béton restent fonctionnels tout au long de leur période d'utilisation. Ces recherches ont conduit au développement des modèles numériques par différentes méthodes à savoir déterministes, probabilistes, différences finies et éléments finis. Le travail de thèse va dans cette direction et vise à analyser le comportement hydromécanique du barrage et explore une amélioration des méthodes de simulation numérique de calcul d’endommagement et éventuelle propagation des fissures suites aux pressions hydrostatiques du réservoir d’eau à l’amont, les sous-pressions exercées par la fondation, les pressions interstitielles à l’intérieur des pores du béton ainsi la poussée hydrodynamique due aux forces de séismes. L’approche proposée est basée sur le modèle champ de phase, cette méthode est souvent utilisée pour analyser les fissures dans des matériaux de manière détaillée, en prenant en compte les propriétés mécaniques du matériau, les contraintes appliquées et l'évolution des fissures au fil du temps. Le modèle calcule l'énergie de déformation associée à la présence de la fissure et aux déformations locales. Cela comprend l'énergie élastique stockée dans le matériau et l'énergie de rupture associée à la propagation de la fissure. L'application du modèle de champ de phase à la propagation de fissures dans le béton est un domaine de recherche avancé qui permet de mieux comprendre et de prédire le comportement des fissures dans les structures en béton. Elle est particulièrement utile pour la conception et l'entretien des infrastructures afin de garantir leur sécurité et leur durabilité. Les résultats montrent que les paramètres du béton (module d’élasticité, énergie de rupture…etc.) influent directement sur la propagation des fissures, elles sont liées à la rigidité de la structure, et définissent la résistance de la structure à la fissure, comme elles peuvent accélérer ou retarder la propagation des fissures. D’autre part, évaluation de l’état initial des déformations et fissures jouent est crucial. Le modèle proposé s’avère être un outil vigoureux d'analyse des déformations et déplacements qui caractérisent le comportement d’un barrage et lui permet de servir d'outil prioritaire lors des études de conception, travaux d'exploitation et de maintenance des barrages-poids en béton. Description: thèse de doctorat Mon, 01 Jan 2024 00:00:00 GMT http://localhost:8080/xmlui/handle/123456789/2293 2024-01-01T00:00:00Z http://localhost:8080/xmlui/handle/123456789/2163 Titre: Irrigation de précision des agrumes et cultures maraichères : cas de la plaine de la Mitidja Auteur(s): Tankeuoo Kopa, Imerina Résumé: Located in northern Algeria, the Mitidja Plain is a vast alluvial region known for its groundwater resources and agricultural importance. However, since the 1980s, the water table has significantly dropped (by more than 40 meters) due to drought and the over-exploitation of water for irrigation (1.3 million hectares irrigated). Poor irrigation management by farmers has further worsened the situation. To improve irrigation systems in the Mitidja Plain and provide better water management through a decision-support tool for farmers, we proposed conducting soil physical studies and water infiltration assessments. This involved determining the impact of organic mulching and studying its combination with drip irrigation systems at different depths for tomato crops. Finally, we compared the most efficient irrigation systems to optimize plant growth while conserving significant amounts of irrigation water for orange trees. Our thesis results show that the soil where tomatoes and orange trees were planted mostly consists of silt, with generally less dense soil, but potential clogging in soils with higher density values. The modified Kostiakov model was the most efficient in the study area. Additionally, analysis of the irrigation water used in the field showed that it was of good quality for plants. For the tomato plots, the mulch made of equal parts wood chips, sawdust, and wheat straw was the most water-conserving over two years (37% - 50%) and required the least irrigation. Furthermore, the comparison of this mulch with BRF (which had also proven effective in past studies), coupled with surface and 15 cm depth drip irrigation, revealed that this same mulch, when combined with subsurface irrigation, saved 29.6% of water and increased yield by 2.9%. The study also confirmed the impact of mulching on soil moisture retention, temperature regulation, and pH, while stabilizing soil salinity over time. This mulching method also showed its importance in improving soil organic matter, with increases of 0.86% - 1.35% in Block A and 0.19% - 0.77% in Block B across the different mulches studied. For the orange tree plots, soil pH ranged from 6.63 to 7.36 over a one-meter depth profile. Comparing the three irrigation systems (S1, S2, S3) revealed that the 30 cm depth drip irrigation system (S3) was the most water-efficient, saving between 14% (2022) and 32% (2023) compared to the surface drip irrigation system (S2). The reduced water consumption was mainly due to drainage or percolation outside the root zone. Root concentration for the orange trees at the station ranged from 40 to 60 cm deep. The 15 cm (S1) and 30 cm (S3) subsurface irrigation systems showed better alignment with Kc and ETc, suggesting more efficient water management, which could be particularly beneficial for maximizing orange production in the Mitidja Plain. Mon, 01 Jan 2024 00:00:00 GMT http://localhost:8080/xmlui/handle/123456789/2163 2024-01-01T00:00:00Z http://localhost:8080/xmlui/handle/123456789/2102 Titre: Impact du changement climatique sur les précipitations extrêmes en Algérie : Risques actuels et futurs Auteur(s): Hamitouche, Yasmine Résumé: This study aims to analyze long-term variability and examine future trends in extreme precipitation indices in response to climate change across various climatic regions of Algeria. Long-term variability analysis of extreme precipitation indices was conducted using daily data from 16 in-situ observation datasets, covering four distinct climatic zones in Algeria from 1969 to 2021. Additionally, future changes were assessed using daily simulations from NASA Earth Exchange Global Daily Downscaled Climate Projections (NEX-GDDP-CMIP6), which are bias-corrected and statistically downscaled. The original Mann-Kendall test and its seven modified version to eliminate the effects of short-long term persistence were employed to examine the long-term variability of precipitation indices between 1969 and 2021. Future trends in these indices were investigated over three distinct periods, based on the SSP245 and SSP585 scenarios: near-future (2026-2050), mid-future (2051-2075), and far-future (2076-2100), relative to the reference period (1990-2014). Our findings, for long-term variability analysis, reveal a significant increasing trend of extreme precipitation variability for most stations in the Warm Mediterranean climate zone (Csa), except for the Consecutive dry days (CDD) index, which showed a negative trend for the same zone, while stations in the Cold/Warm semi-arid climate and Cold desert climate (Bwk) zones showed a decreasing trend. Additionally, all index series with significant long-term trends were affected by a significant shift in their means, which was confirmed by both the Lombard (LT) and Pettitt tests (PT). The results of the analysis of the future evolution of extreme precipitation indices vary from one index to another, from one model to another, and from one region to another. Despite differences among individual models, the multi-model ensemble MME-33 predicts a decrease in annual precipitation in coastal and plateau regions (zones 1 to 4), with average declines of 16.1%, while desert regions (zone 5) could see an increase of 8.1%. Extreme precipitation indices such as Rx1day, Rx5day, and R99p show an upward trend across all zones, with increases ranging from 2.5% to 25.9% under different climate scenarios. For heavy precipitation days (R20mm), forecasts indicate decreases in zones 1 and 2, possible increases in zone 3, and stable variations in zones 4 and 5. Overall, more than 70% of models predict reduced annual precipitation in zones 1 to 4 and an increase in zone 5, along with an increase in Rx1day and R99p indices across all zones. Compared to the historical period, future projections show an increased likelihood of extreme precipitation events, including those exceeding 35 mm/day for Rx1day and 100 mm/5 days for Rx5day in northern zones. Extremely heavy precipitation events (R99p) could also become more probable, albeit rare, with values exceeding 50 mm in all zones. Conversely, the probability of daily precipitation events ≥20 mm may decrease in some zones, reflecting complex changes in future precipitation regimes. Description: Doctorat Mon, 01 Jan 2024 00:00:00 GMT http://localhost:8080/xmlui/handle/123456789/2102 2024-01-01T00:00:00Z http://localhost:8080/xmlui/handle/123456789/2101 Titre: Etude de stabilité structurelle d'un barrage poids en béton par approche d'optimisation fiabiliste Auteur(s): Kerkar, Mohamed Essaddik Résumé: The safety of dams is a priority at the international level, based on a large amount of data from a dam-reservoir allows analysts to make an optimization on its structural stability; the latter is based on the estimation of the probability of failure from the effects of stress and resistance acting on the dam-reservoir system. This investigation is to establish a methodology in order to optimize the safety of a concrete gravity dam in operation by carrying out a risk analysis which includes the identification of the sources of danger in terms of scenarios that can occur due to a failure on the dam-reservoir system on an implication of natural hazards (floods, earthquakes) and technical accidents such as malfunction of a spillway gate, drain valve, drainage system or important silting. Reliability methods provide a basis for the probabilistic assessment of the structural safety of a dam, they make it possible to take into account in a probabilistic context, the uncertainties in the data associated with the calculation parameters used in the justifications of structural stability and make it possible to assess as closely as possible the intrinsic safety of a concrete gravity dam. Description: doctorat Mon, 01 Jan 2024 00:00:00 GMT http://localhost:8080/xmlui/handle/123456789/2101 2024-01-01T00:00:00Z