Leakage below dam sites in limestone terrains by enhanced karstification: a modeling approach |
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Authors: | Douchko Romanov Franci Gabrovsek Wolfgang Dreybrodt |
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Institution: | 1. Department of Earth Sciences, Freie Universit?t Berlin, Berlin, Germany 2. Karst Research Institute ZRC SAZU, Postojna, Slovenia
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Abstract: | Unnaturally high hydraulic gradients below dam sites enhance dissolutional widening of fractures in limestone. A model is
presented which suggests that under unfavorable conditions, leakage rates could become unbearably high during the lifetime
of the dam. At the beginning when water is impounded, leakage rates are low and increase slowly. A positive feedback loop,
however, causes a sudden dramatic increase of leakage within a few years. Deep grouting becomes necessary to prevent such
failures. Inefficiencies in grouting may leave some open fractures in the grouting curtain. These fractures widen faster than
pathways below the grouting curtain, and reduce the effect of the grouted region located below. Therefore, open fractures
act in a similar way as reduction of the grouting depth. |
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Keywords: | Dissolution of limestone Karstification Dam site |
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