Backward Piping In Multi-Layer Dike Foundations: Experiments And Model Validation

Backward piping is a dominant failure mechanism both on homogenous and multi-layer aquifer dike foundations. Studies and statistics indicate that backward piping on dike foundations severely threat dike safety both in China and The Netherlands. The safety is assessed by the so-called 'rule of Sellmeijer' that has been developed and validated to predict piping in homogenous dike foundations. However, multi-layer dike foundations often occur in practice, and the influence of the multi-layer system has to be validated by experimental work and included in calculation rules for dike safety assessments. Therefore small scale experiments with different setups are performed to investigate backward piping in multi-layer dike foundations. An addition to the rule of Sellmeijer for the multi-layer system has been derived by model validation work based on these experiment results. This paper will introduce experimental work on piping in a multi-layer dike foundation configuration consisting of a coarse sand layer below a fine sand layer. The results of the experiments are used to update and validate the calculation model. The existing calculation rule is extended to be applicable for multi-layer dike foundations.