Volume Change Induced Cracking of Flood Protection Dikes Built of Clay

摘要

Severe cracking of dikes following an extreme period of drought turned attention to the impact of shrinkage on dikes built of unsaturated clays of high plasticity. Laboratory tests revealed a unique linear relationship between loss in moisture ocntent and ensuin volume change of compacted unsaturated clay fill. Volume change appeared to come invariably to an end the moment the moisture content, the "drivign agent", dropped to a value termed as the "limit of linear shrinkage". Tests on briquette samples showed a characteristically brittle behaviour of the clay in tension. Differential volumetic strains propagating from teh exposed free surfaces towards the inner parts to the dike were bound to lead to the formation of cracks. The paper also addresses in brief the problems envountered in detection of crackes, the impact of cracking on serviceability and soundness of dikes and a review ofsuggested rehabilitation methods.