مجله ژئوفیزیک ایران

مجله ژئوفیزیک ایران

بررسی پارامترهای مقاومت برشی ماسه مسلح به EVA بر اساس آزمایش برش مستقیم

نوع مقاله : مقاله پژوهشی‌

نویسندگان
1 استادیار گروه مهندسی عمران، دانشکده فنی و مهندسی، دانشگاه صنعتی قم، قم، ایران
2 دانش آموخته گروه مهندسی عمران، دانشکده فنی و مهندسی، دانشگاه صنعتی قم، قم، ایران
3 دانشیار گروه مهندسی عمران، دانشکده فنی و مهندسی، دانشگاه صنعتی قم، قم، ایران
چکیده
تثبیت و تسلیح خاک‌ها از دیرباز نقش مهمی در علوم عمرانی به خصوص در علم ژئوتکنیک ایفا کرده‌است و با گذشت زمان و نیاز به زمینی مقاوم‌تر و با ثبات‎‎‎‎‌تر برای تحمل بارهای ثقلی و نیروهای برشی بیشتر، از اهمیت ویژه‌‌‌ای برخوردار گردیده‌است. هم‌چنین در سال‌های اخیر با ورود محیط‌زیست به صنعت ساخت‌و‌ساز، با هدف کاهش اثرات نامطلوب ضایعات صنعتی و نخاله‌های ساختمانی برمحیط زندگی افراد و حفظ محیط‌زیست برای آیندگان، در بسیاری از موارد باعث کاهش هزینه‌های اقتصادی پروژه‌ها نیز می‌گردد. در این پژوهش، به تسلیح خاک ماسه‌ای در دو حالت سست و نیمه متراکم با استفاده از ماده ضایعاتی صنعتی پلیمری با نام کامل اتیلن-وینیل استات(Ethylene-Vinyl Acetate EVA:) با هدف بررسی اثر این ماده افزودنی بر پارامتر‌های مقاومت برشی خاک ماسه‌ای پرداخته شده‌است. آزمایش‌‌ها در درصد‌های مختلف وزنی EVA (0، 2/0، 5/0، 1، 5/1، 2 و 5/2)، بدون افزودن رطوبت و به شیوه درصد وزنی صورت گرفته‌است. آزمایش‌ها با استفاده از دستگاه برش مستقیم کوچک مقیاس انجام گرفته و نتایج بدست آمده نشان می‌دهد افزودن این ماده ضایعاتی به خاک در دو تراکم مختلف باعث افزایش هر دو پارامتر چسبندگی و زاویه اصطکاک داخلی خاک مسلح شده‌است که اثر آن بر روی زاویه اصطکاک مشهودتر بوده و اثر افزایش مقاومت برشی آن بر خاک سست بیشتر از خاک متراکم است؛ با این وجود مقدار بهینه، در 1% افزودنی برای هر دو حالت سست و نیمه‌متراکم اتفاق می‌افتد.
کلیدواژه‌ها

عنوان مقاله English

Shear strength parameters evaluation of sand reinforced with EVA based on direct shear test

نویسندگان English

Masoud Amelsakhi 1
Mahsa Miri 2
Morteza Jiryaei Sharahi 3
1 Assistant Professor, Civil Engineering Department, Faculty of Engineering, Qom University of Technology, Qom, Iran
2 Graduated Student, Civil Engineering Department, Faculty of Engineering, Qom University of Technology, Qom, Iran
3 Associated Professor, Civil Engineering Department, Faculty of Engineering, Qom University of Technology, Qom, Iran
چکیده English

Soil stabilization and reinforcement has long and important role in civil sciences, especially in geotechnical engineering, and need for a more robust and stable ground to withstand gravity and higher shear forces, has become particularly important. Using waste materials reduces the negative environmental effects and also decreases shear strength parameters of soils. These waste materials are very cheap, so theses reinforcements are more benefit in comparison with other high price reinforcements. Also, in recent years, with the entry of the environment into the construction industry, with the aim of reducing the adverse effects of industrial waste and construction waste on people's living environment and preserving the environment for the future, in many cases reduces the economic costs of projects. In this research, sandy soil is reinforced in both loose and semi-dense states using polymer industrial waste material called ethylene-vinyl acetate (EVA) with the aim of investigating the effect of this additive on the shear strength parameters of sandy soil. The experiments were performed at different weight percentages of EVA (0, 0.2, 0.5, 1, 1.5, 2 and 2.5) without adding moisture and by weight percentage method. The experiments were performed using a small-scale direct cutting machine, which shows that the addition of this waste material to the soil at two different densities increases both the adhesion parameters and the internal soil friction angle, which has a more pronounced effect on the friction angle and the effect of increasing shear strength It has more positive effect on loose sand rather than dense sand. The optimum value occurs in 1% additive for both loose and semi-dense sands. EVA reinforces the sand, in another word, it increases the cohesion of the reinforced sand-EVA mixture and also the soil-EVA friction angle. These physical particles has an interlocking role in the sand-EVA mixture and this interlocking effect is the main reason for the increase of the shear strength parameters of the mixture; cohesion and the friction angle. It should be mentioned that the size of EVA and the percentage in the mixture is very important. Another practical and important note is the compaction of the sand-EVA mixture in the field and the project sites. This limitation should be considered when using this flexible material, especially in high per cent contents in the mixture. This matter limited the content of this material in our laboratory test, such as direct shear tests. In all the tests, the sand-mixture is dry and the water content effect is neglected in direct shear tests.  

کلیدواژه‌ها English

Soil improvement
waste material
EVA
direct shear
environment
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