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Prevention of internal erosion by cut-off walls in river embankments on the upper rhine / Bernhard Odenwald in La Houille blanche, N° 4-5 (Octobre 2012) 

Public ISBD [article]  in La Houille blanche > N° 4-5 (Octobre 2012) . - pp. 48-53 Titre : Prevention of internal erosion by cut-off walls in river embankments on the upper rhine Titre original : Prévention de l’érosion interne par des murs parafouilles dans les digues du Rhin supérieur Type de document : texte imprimé Auteurs : Bernhard Odenwald, Auteur ; Kerstin Ratz, Auteur Année de publication : 2012 Article en page(s) : pp. 48-53 Note générale : Hydraulique Langues : Anglais (eng) Mots-clés : Internal  erosion  Suffosion  River  embankment  Rehabilitation  Cut-off  wall Résumé : Between 1928 and 1971, a total of 10 barrages including river embankments with a height of up to approx. 10 m were erected on the Upper Rhine between Basel and Karlsruhe. The river embankments were constructed using local building materials : the shells consists of sandy gravel, and the cores of a silty material (alluvial loam). The in-situ sandy gravels in the Upper Rhine region show a pronounced grain-size gap for coarse-grained sand and fine gravel which is why they are not resistant to suffosion. This lack of suffosion resistance affects both the ground below the river embankments and their shells. Furthermore, the filter stability of the silty soil material used in the cores is not sufficient to filter the sandy gravels of the ground below the embankments and/or their shells. Immediately after flooding of the impoundments, the exit of seepage water was observed on the downstream embankment slopes. Due to the embankment material’s lack of suffosion resistance and filter stability this caused a loss of soil in certain areas. To improve the situation, and working from the crest downwards, cut-off walls (diaphragm walls, injection walls and sheet pile walls) were subsequently driven into the river embankments over long stretches. These increase the length of the seepage path, thus reducing the hydraulic gradients in the embankment and the ground. The resulting reduction of the seepage forces reduces the risk of internal erosion. The efficiency of the cut-off walls embedded in the embankments subject to seepage depends on the overall ground situation and the groundwater flow characteristics on the one hand, and on the walls’ resistance to geohydraulic load on the other hand. ISSN : 0018-6368 En ligne : http://www.shf-lhb.org/index.php?option=com_article&access=standard&Itemid=129&u [...] [article] Prevention of internal erosion by cut-off walls in river embankments on the upper rhine = Prévention de l’érosion interne par des murs parafouilles dans les digues du Rhin supérieur [texte imprimé] / Bernhard Odenwald, Auteur ; Kerstin Ratz, Auteur . - 2012 . - pp. 48-53. Hydraulique Langues : Anglais (eng) in La Houille blanche > N° 4-5 (Octobre 2012) . - pp. 48-53 Mots-clés : Internal  erosion  Suffosion  River  embankment  Rehabilitation  Cut-off  wall Résumé : Between 1928 and 1971, a total of 10 barrages including river embankments with a height of up to approx. 10 m were erected on the Upper Rhine between Basel and Karlsruhe. The river embankments were constructed using local building materials : the shells consists of sandy gravel, and the cores of a silty material (alluvial loam). The in-situ sandy gravels in the Upper Rhine region show a pronounced grain-size gap for coarse-grained sand and fine gravel which is why they are not resistant to suffosion. This lack of suffosion resistance affects both the ground below the river embankments and their shells. Furthermore, the filter stability of the silty soil material used in the cores is not sufficient to filter the sandy gravels of the ground below the embankments and/or their shells. Immediately after flooding of the impoundments, the exit of seepage water was observed on the downstream embankment slopes. Due to the embankment material’s lack of suffosion resistance and filter stability this caused a loss of soil in certain areas. To improve the situation, and working from the crest downwards, cut-off walls (diaphragm walls, injection walls and sheet pile walls) were subsequently driven into the river embankments over long stretches. These increase the length of the seepage path, thus reducing the hydraulic gradients in the embankment and the ground. The resulting reduction of the seepage forces reduces the risk of internal erosion. The efficiency of the cut-off walls embedded in the embankments subject to seepage depends on the overall ground situation and the groundwater flow characteristics on the one hand, and on the walls’ resistance to geohydraulic load on the other hand. ISSN : 0018-6368 En ligne : http://www.shf-lhb.org/index.php?option=com_article&access=standard&Itemid=129&u [...]