3D character of backward erosion piping: small-scale experiments

Backward erosion piping is an important failure mechanism for cohesive water retaining structures which are founded on a sandy aquifer. At present, the prediction models for safety assessment are often based on 2D assumptions. In this work, the 3D character of the phenomenon is demonstrated on the basis of small-scale experiments. Our approach reveals the correlation between the occurrence of piping initiation and progression and the width of the physical model, which is a measure for the inclusion of the third dimension (to be regarded in a real dike situation as the influence zone of a crater). In addition, it was found that the model width has an impact on pipe characteristics and pipe development. Therefore, our results enable a better understanding of the complex physical mechanism related to backward erosion piping and thus can lead to a significant improvement in the safety assessment of water retaining structures