Influence of rate of hydraulic gradient on washed-out soil mass due to perpendicular contact erosion or poor filter design

Conference Publication ResearchOnline@JCU
To, Peter;Price, Peter
Abstract

Contact erosion is a major type of internal erosion. It occurs at the interaction of a soil layer and filter. Based on the direction of seepage flow, traditional contact erosion comprises of perpendicular and parallel contact erosion. When soil particles are smaller than pore constrictions formed by the filter, they can be washed out sequentially if the flow at this interaction surface is strong enough. However, if the pore sizes are not too far from the particle sizes, a high hydraulic gradient may cause a jamming effect, which reduces the washed-out amount. This paper studies the washed-out amount in perpendicular contact erosion of the same soil under two hydraulic conditions: (1) an immediate jump and (2) a gradual, multi-step change. Soil is compacted to a predefined degree by Multi Testing System (MTS) and tested in a transparent erosion unit. The hydraulic head difference is varied from 2 to 5 m. The change is measured with pressure sensors and recorded continuously with a data logger. The laboratory results show a significant difference in the washed-out amount.

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10th International Conference on Scour and Erosion

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9

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Online

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International Society for Soil Mechanics and Geotechnical Engineering

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Arlington, VA, USA

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