YAO Qiu-ling 1, 2, LIU Chang-jun 1, 2, DING Liu-qian 1, 2, ZHANG Shun-fu 1, 2

1. China Institute of Water Resources and Hydropower Research, Beijing 100038, China
2. Center of Disaster Reduction of the Ministry of Water Resources, Beijing 100038, China

Abstract: Small scale experiments are conducted to try to explain the microcosmic mechanism of frequent backward piping in dike foundations during flood seasons. The sand matrix is photographed and recorded by zooming in video using the microscope and digital imaging analysis system during the experiments. By combining common visual observation of the phenomenon with analysis of the particle grading during different water head by digital image acquisition system, the particle displacement and loss pattern along with the water head increasing are analyzed. The mechanism of backward piping is explained both from macroscopic and microcosmic view. The experiments show that the particle displacement and loss process are consistent with the observed phenomenon. The process of backward piping just reflects the particle displacement and loss process. Based on the integrated analysis on the particle displacement and piping channel progress, the backward piping mechanism is explored more deeply. This research will trigger the inspiration for establishing both mathematical and numerical models, and is also useful for improving the technology of countermeasures against backward piping.

Key words: dike foundations, backward piping, microcosmic mechanism, particle loss, model experiments

Published in: Journal of China Institute of Water Resources and Hydropower Research (Vol. 12 No. 1, 2014)