Laboratory study on the effectiveness of nanoclay in internal erosion of Dispersive Clayey Soils in embankmen dams

Document Type : Original Research

Authors
M. mzomorod
H. Ghafari
M. Izadi
Shiraz University
Abstract
Construction of hydraulic structure on dispersive soil created a lot of problems such as piping or internal erosion. Since it is not economical to change dispersive soil with non- dispersive soil, therefore, it is very important to improve the erosion resistance of soils using appropriate and cost effective techniques. This research is intended to study the effect of adding nano-clay on erodibility of dispersive soil. The nano-clay (montmorillonite) has been used as a modern and eco-friendly additives for controlling internal erosion in dispersive soils. To conduct this research, dispersive soil has been treated with four different percentages (i.e. 0, 0.5, 1, 1.5 and 3 % by weight of the parent soil) of nano-clay. The Variables taken into account are the curing time (i.e. 1, 2, 7, 14 and 28 days) and the mixing percentages. Erodibility parameters were obtained by the Hole Erosion Test (HET) in different hydraulic gradients (i.e. 7.05, 7.96 and 11.05). It is found that increase in nano-clay content is increasing the resistance of dispersive soil to erosion. The optimum amount of nanoclay in reducing erosion for samples of one day curing time was obtained 1% and the erosion index rate was 4.33. For 2 and 7 days curing times the optimum amount of nanoclay was observed equal to 1.5% and the index of erosion rate was 4.85 and 4.72, respectively. It was also observed that in larger hydraulic gradients, the effect of nanoclay in reducing erosion is more. Also, increasing nano-clay addetive changed plastic index properties of soil.

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Modares Civil Engineering journal
Volume 19, Issue 2
July and August 2019
Pages 101-112