MATERIAL PROPERTIES AS A MEASURE OF THE AGING EFFECTS OF EMBANKMENT DAMS (Published)
Aging of embankment dams and their foundations is of concern to persons involved in their design, construction and operation. It is due to time-related changes in the structural properties of the materials of which the dam and its foundation are composed. Indirect evaluation of aging is by monitoring the effects and consequences of changes in structural properties and the actions causing them.This paper examined the geotechnical properties of ten (10) selected earth dams, from two States in the South-western Nigeria to consider aging effects on their materials properties. Soil samples were obtained from upstream and downstream sides of the dams from six locations at depth of 1.2 m. Geotechnical tests were carried out to determine Specific gravity, Soil classification, Maximum Dry Density (MDD) and Optimum Moisture Content (OMC), Liquid Limits (LL), Plastic Limit (PL), Plasticity Index (PI), and Coefficient of Permeability (CP). The results showed migration of fine grain (clay materials) from upstream to downstream side of the dam; which was an indication of fracturing within the embankments; thus, internal erosion is a possibility within the fractured zones. Prevention and mitigation of aging could be achieved through quality design, construction and operation. A well planned and performed monitoring program will help in early detection of aging scenarios; and provision of convenient access to all vital areas of the dam will enhance surveillance and regular maintenance.
Keywords: Aging scenarios, Indirect evaluation, Internal erosion, Regular maintenance, Structural properties