نوع مقاله : یادداشت فنی
1 بخش مهندسی آب - دانشگاه شیراز
2 دانشکده مهندسی عمران، دانشگاه آزاد اسلامی، واحد استهبان
عنوان مقاله [English]
Dispersive soil is founded in many parts of Iran and world, and construction of hydraulic structure on dispersive soil created a lot of problems such as piping or internal erosion. Due to internal erosion of an earth dam water that seeps through the dam carries soil particles away from the embankment, foundation, or abutments of the dam. Internal erosion may be a result of inadequate compaction during construction, differential settlement, desiccation, earthquakes, burrowing animals, and/or vegetation roots. The erodibility of the material in the internal erosion flow path along with hydraulic stresses is the most important factors in determining the rate of erosion. The challenge in predicting failure due to internal erosion characterizes the material properties relevant to the rate of failure. Since it is not economical to change dispersive soil with non-dispersive soil, it is very important to improve the erosion resistance of soils using appropriate and cost-effective techniques. Using chemical stabilizers is one of the effective methods to
prevent internal erosion in earth dams. This research is intended to study the effect of adding nano-$SiO2$ on erodibility of dispersive soil.The new stabilizer nano-$SiO_2$ is utilized for the evaluation of its effectiveness in increasing erosion resistance. To conduct this research, dispersive soil has been treated with three different percentages (i.e., 1, 2, 3 \% by weight of the parent soil). Erodibility parameters were obtained by Hole Erosion Test (HET). The variables taken into account are the curing time (i.e., 1, 7, 14 days) and the mixing percentages. It is found that erosion rate of dispersive clay is extremely rapid, and the increase in nano-$SiO_2$ content results in increasing the resistance of dispersive soil to erosion. It was also found that the erodiblity of dispersive soil increase 2 to 14 \% in 2 and 3 \% nano-$Sio_2$ content compared to 1 \% nono-$Sio_2$. With increasing curing time, the erodibility index of dispersive soil increases 4 to 7 \%, meaning that erodibility of dispersive soil is reduced.