Free vibration characteristics of earthen dams

The present study makes an effort to explain the crest failure of earthen dams. The free vibration analysis of a two-dimensional section of an example earthen dam is carried out. The frequencies and mode shapes are presented. The tendency of lateral extension at the crest in first few modes clearly explains the occurrence of longitudinally propagating vertical crack in earthen dams observed during recent earthquake of Gujarat. The study also shows that modifications in the sectional configurations do not alter the dynamic characteristics favorably and appreciably though the same modifications are found to be effective in eliminating tension from crest under static loading.