AN EXPERIMENTAL STUDY OF CRACKING, LEAKAGE AND EROSION IN EARTH AND EARTH ROCK FILL DAMS

Abstract

Internal cracks are developed in earth dams due to the differential settlement depending upon the type and shape of valley and non-homogeneity of the materials of embankments and foundations. These cracks are very danger-ous to the stability of a dam when leakage and erosion starts, causing formation of piping channels. An apparatus wasdesigned and fabricated to conduct an experimental study on the combined effect of cracking,leakage and erosion through earth dam materials. Four artificial soil were prepared to represent four widely different types of grain size distributions curves. The soils were compacted at -2.5/. o.m.c., o.m.c. and +2.5/. o.m.c. in the test mould. The pulling force for cracking the soil sample has been applied by triaxial machine at a rate of 00125 mm/min. A horizontal crack developed within the soil sample at limit-ing tensile stress resulting in leakage and erosion which were collected and measured. carefully. Experiments have been performed for the hydraulic gradients of 0,5 and 10. It was very interesting to observe that leakage and erosion started and stopped after some time indicating the self-healing characteristics of a soil. Soil No.4 exhibited self-healing characteristics upto a maximum crack width of 1.50 mm probably because it was well graded and centained practically no clay.