پ۲۴۷۰۷
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تثبیت شیمیایی و بیولوژیک خاک رس بستر راه و تاثیر آن بر مدول برجهندگي (MR)
سیامک شفقتیان
پردیس دانشگاه تبریز
۱۴۰۰
۲۰۷ص.
سی دی
دکتری
مهندسی عمران گرایش: ژئوتکنیک
۱۴۰۰/۰۴/۱۳
تثبیت شیمیایی خاک ضعیف بستر راه، یک روش مناسب و ضروری برای پرهیز از مشکلات جایگزینی خاک ضعیف با منابع منتخب قرضه به لحاظ اقتصادی و زیست محیطی است. در تثبیت شیمیایی، استفاده از مصالح نوین از جمله پلیمرها به جای مصالح سنتی مانند آهک موجب تسریع عملیات و همچنین کاهش فشار بر منابع می¬شود ولی آثار زیست محیطی و مقاومت دراز مدت این روش¬ها دغدغه متخصصین است. اخیرا طبق توصیه پیمان زیست محیطی کیوتو در بخش تثبیت خاک با اهداف ژئوتکنیکی، تحقیق بر روی روش¬های نوین تثبیت خاک از جمله روش زیستی، گسترش یافته است
Chemical stabilization of weak subgrade soil is a viable and essential method of avoiding weak soil replacement problems with selected borrow pit in economically and environmentally point of view. Although the use of nontraditional materials such as polymers instead of traditional materials such as lime accelerates operations and reduces resource pressure, the environmental impact and long-term resistance in these methods are concerns for experts. Recently, according to the “Kyoto Environmental Protocol” recommendation on soil stabilization with geotechnical purposes, research on new methods of soil stabilization including "soil biological stabilization" has been developed. In this study, the effect of clay subgrade stabilization with chemical and biological methods was investigated and compared through different experiments. The soil of a significant part of the northern region of Mazandaran is fine-grained and weak for subgrade construction, and the lack of suitable resources in these areas makes replacement operation in road construction projects very costly and time consuming. Therefore, reviewing and presenting a suitable soil stabilization plan in this area is an essential need in order to optimize the project. Therefore, the soil of Amol-Sari freeway in this area has been selected for study. For chemical stabilization, a liquid polymer called cationic polyelectrolyte (CPE) and a solid polymer called Nicoflok was used. For biological stabilization, the microbial induced calcium carbonate precipitation (MICP) method was adopted and a biopolymer solution called Beta-glucan was employed. In both methods, the specific dry weight of soil decreased and its optimum moisture content increased. CPE increased Plastic Index while other stabilizers reduced it. All four additives increased the pH of the environment for up to three days. They also contributed to a growth in the uniaxial compressive strength and the elasticity modulus of the soil. The effect of solid polymer and biopolymer was more significant. Despite similar results in the uniaxial test, the solid polymer increased the resilient modulus (MR) of the stabilized soil more than the biopolymer. It should be noted that the resilient modulus is one of the most important parameters in road design. Increasing the dose of the stabilizers and the curing time of the samples changed the resilient behavior of the fine-grained soil to the behavior of a coarse-grained soil under different stress conditions Nicoflok and biopolymer-stabilized samples exhibited a higher CBR and durability compared to the untreated sample, with the effect of Nicoflok being more significant. The estimate of design MR for these samples using the stress-dependent model of National Cooperative Highway Research Program (NCHRP) was more accurate compared to the conventional correlations with CBR. Therefore, chemical stabilization with the solid polymer is economically feasible while biological stabilization using the biopolymer is environmentally suitable for the studied soil.
Chemical and biological stabilization of subgrade clay soil and its impact on resilient modulus (MR)
شفقتیان
سیامک
تهيه کننده
مرادی
کاتبی
غلام
هوشنگ
استاد راهنما
استاد مشاور
تبریز
