كليدواژه :
خاك واگرا , نانوسيليس , فرسايش داخلي , آزمايش فرسايش حفره , زمان عمل‌آوري
چكيده فارسي :
پديده‌ي واگرايي باعث شكل‌گيري پديده‌ي پايپينگ يا فرسايش داخلي در سدهاي خاكي شده و درنهايت منجر به تخريب آن مي‌شود. گستره‌ي وسيع خاك‌هاي واگرا، همچنين غيراقتصادي بودن جاگزيني منابع قرضه‌ي واگرا با منابع غير واگرا، اصلاح خاك‌هاي واگرا را ضروري مي‌سازد. از جمله افزودني‌هاي شيميايي جهت تثبيت خاك واگرا، مي‌توان به نانوسيليس اشاره كرد. در پژوهش حاضر، از آزمايش فرسايش حفره (HET) استفاده و با افزودن نانوسيليس به نمونه‌ي خاك واگرا، فرسايش‌پذيري خاك با درنظر گرفتن دو متغير زمان عمل‌آوري در دوره‌هاي 1، 7 و 14 روزه و درصد وزني 1، 2 و 3 درصد نانوسيليس ارزيابي شده است. طبق نتايج، فرسايش‌پذيري خاك‌هاي واگرا با نانوسيليس در درصدهاي 2 و 3 نسبت به 1%، 2 تا 14 درصد افزايش يافته و با افزايش دوره‌ي زماني، باعث عملكرد بهتر نانوسيليس و افزايش 4 تا 7 درصدي شاخص نرخ فرسايش در خاك‌هاي واگرا شده است.
چكيده لاتين :
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-SiO2 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-SiO2 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-Sio2 content compared to 1 % nono-Sio2. With increasing curing time, the erodibility index of dispersive soil increases 4 to 7 %, meaning that erodibility of dispersive soil is reduced.
