Technology of Remediation of Embankment Dams by Optimal Grout

Abstract

Floods represent one of the greatest direct dangers of natural disasters in Europe. During floods, substantial material damage and often even losses of human life may occur. In the Czech Republic both of these were recorded in 1997 and 2002, which were catastrophic floods. Among flood measures belong dams of reservoirs and barriers along the rivers, which must be sufficiently water-tight. Dam and dam foundation leaks may be affected by the homogeneity of dam and the sealing element. Often there is damage to these parts of the dam and thus leakage can take place. These leaks occur mainly due to the age of the dam, uneven subsidence, and bad compaction during construction etc. In case of insufficient sealing it is also necessary to secure the dam, which can be done only by means of remediation. This paper briefly introduces the technology of remediation of embankment dams and summarises the research dealing with the optimal grout development (with partial replacement of raw materials by waste product – fly ash). It is important to choose appropriate material composition and the proper selection of implementation technology. The choice of materials, technology of implementation, number and distribution of boreholes are influenced by the damage to the dam, the amount of leakages and its composition, which is detected by a ground-penetrating radar survey. Mixtures were prepared using clay, lime and two types of fly ash, and the physico-mechanical properties of the designed grouts were determined. After selecting the mixture for a given type of dam, before the actual application, it is important to perform laboratory and also “in situ” assessment. The most common assessment method on in situ is determining the consistence using the Marsh cone. The influence of the fly ash (and its type) addition on the final properties of the grout was observed and assessed. Checking the extent of dam grouting is done using a ground-penetrating radar.Floods represent one of the greatest direct dangers of natural disasters in Europe. During floods, substantial material damage and often even losses of human life may occur. In the Czech Republic both of these were recorded in 1997 and 2002, which were catastrophic floods. Among flood measures belong dams of reservoirs and barriers along the rivers, which must be sufficiently water-tight. Dam and dam foundation leaks may be affected by the homogeneity of dam and the sealing element. Often there is damage to these parts of the dam and thus leakage can take place. These leaks occur mainly due to the age of the dam, uneven subsidence, and bad compaction during construction etc. In case of insufficient sealing it is also necessary to secure the dam, which can be done only by means of remediation. This paper briefly introduces the technology of remediation of embankment dams and summarises the research dealing with the optimal grout development (with partial replacement of raw materials by waste product – fly ash). It is important to choose appropriate material composition and the proper selection of implementation technology. The choice of materials, technology of implementation, number and distribution of boreholes are influenced by the damage to the dam, the amount of leakages and its composition, which is detected by a ground-penetrating radar survey. Mixtures were prepared using clay, lime and two types of fly ash, and the physico-mechanical properties of the designed grouts were determined. After selecting the mixture for a given type of dam, before the actual application, it is important to perform laboratory and also “in situ” assessment. The most common assessment method on in situ is determining the consistence using the Marsh cone. The influence of the fly ash (and its type) addition on the final properties of the grout was observed and assessed. Checking the extent of dam grouting is done using a ground-penetrating radar.