Experimental study of seawall piping under water level fluctuation

Abstract

The hydraulic action, such as waves, tides and floods, is the main cause of piping failure in seawall engineering, while the suffusion failure mechanism in this case has not been specially studied. Indoor experimental studies of piping failure of seawall under the waves and tidal water level fluctuations are still in a blank state. Based on the designed experimental devices in the research work, six groups of model tests were carried out with crushed and round gravel. The seepage velocity, seepage gradient, permeability coefficient and the fine particle movement trends were analysed. The changing rules of these variables under water level cycle were studied. It has been found that the critical hydraulic gradient of the fine piping particles inside the seawall became smaller with the increase in water level fluctuation cycles. At the same time, the critical flow velocity tended to increase gradually. The piping occurrence probability in the round gravel-filled seawall was larger than that in the crushed gravel-filled seawall. The internal fine-grained structure showed dynamic changes in migration under the fluctuation of the water level cycle.

Keywords:

• water level cycle fluctuations
• seawall engineering
• piping
• permeability coefficient

Acknowledgements

This paper is supported by the 111 Project (No. B13024), Program for Changjiang Scholars and Innovative Research Team in University (No. IRT1125), the open fund of National Inland Waterway Regulation Engineering Research Centre (No. SLK2011A02), and Graduate research and innovation plan project for the regular institution of higher learning in Jiangsu province (No. CXLX12_0243).