Assessing potential for internal erosion in glacial moraine core embankment dams
2007 (English)In: Dam Engineering, ISSN 0958-9341, Vol. 18, no 2, 101-117 p.Article in journal (Refereed) Published
Internal erosion, the process of washout of fine-grained material by seepage flow from an embankment dam filling material, can pose a major threat to dam safety. Internal erosion at a far reached stage can surface in the shape of sinkholes, sudden turbid leakages and settlements, indicating that the filling material in the dam is undergoing potentially significant property changes. It was early on found, for instance by Sherard , that embankment dams comprising broadly graded material appear to develop sinkholes more frequent than dams of other material components. And considering that typical Swedish embankment dams are composed of material with broad and wide gradations of glacial origin, in particular the impervious core of broadly graded moraine (till), it should come as no surprise that many embankment dams in Sweden have shown signs of deterioration that can be related to internal erosion. The susceptibility for internal erosion in Swedish embankment dams was perhaps first noticed in a survey carried out by Nilsson et al , where 20 % of the incorporated dams were estimated being affected by internal erosion. To reduce the risks connected to internal erosion it can be necessary to implement dam safety measures preferably at an early stage before the internal erosion progressed to surfacing, but distinguishing which dams that hold a real potential future risk for internal erosion can prove difficult. This paper is based on an evaluation comprising 45 existing Swedish embankment dams and the results show that a more discriminatory predictor, than today’s filter criteria, appears to be needed if embankment dams with widely graded glacial cores with high potential for surfacing internal erosion are to be singled out from dams apparently internal erosion free. The results indicate that not only filter coarseness needs to be addressed when assessing potential for internal erosion in embankment dams with glacial moraine cores, but also the internal stability of the core and filter.
Place, publisher, year, edition, pages
Kent UK: Global Trade Media , 2007. Vol. 18, no 2, 101-117 p.
dams, internal erosion, moraine, filter, prediction method
Mineral and Mine Engineering
IdentifiersURN: urn:nbn:se:kth:diva-14055OAI: oai:DiVA.org:kth-14055DiVA: diva2:329515
QC 201007122010-07-122010-07-122012-12-17Bibliographically approved