مهندسی سازه و ساخت

مهندسی سازه و ساخت

تاثیر الیاف کنف بر مقاومت فشاری محصورنشده و پارامترهای برشی مستقیم نمونه‌های ماسه‌ای بهبود‌یافته با سیمان، زئولیت

نوع مقاله : علمی - پژوهشی

نویسندگان
1 دانشجو دکتری گروه مهندسی عمران، واحد تهران جنوب، دانشگاه آزاد اسلامی، تهران، ایران
2 دانشیار گروه مهندسی عمران و مرکز تحقیقات مدلسازی و بهینه سازی در علوم و مهندسی، واحد تهران جنوب، دانشگاه آزاد اسلامی، تهران، ایران
3 استادیار گروه مهندسی نفت و معدن، واحد تهران جنوب، دانشگاه آزاد اسلامی، تهران، ایران
4 دانشیار گروه مهندسی عمران، واحد اراک، دانشگاه آزاد اسلامی، اراک، ایران
چکیده
از مهمترین دشواری‌ها در زمینه پیسازی در پروژههای عمرانی مقاومت کم خاک بستر، وجود خلل و فرج و حضور آب در این حفرات به مقدار نامطلوب است و این مساله در خاک منطقه ساحلی که بیشتر از نوع ماسه بادی یا ماسه شل و اشباع است؛ مشکلات زیادی را بهوجود می‌آورد. در بهسازی خاک‌ها، روش‌های متنوعی وجود دارد که با توجه به شرایط اقتصادی، اجرایی و زیست-محیطی پروژه‌ها، مورد استفاده قرار می‌گیرند. با توجه به انطباق‌پذیری زیاد روش تثبیت شیمیایی با شرایط مختلف حاکم بر پروژهها، یکی از رایج‌ترین راه‌های بهسازی خاکها تلقی میگردد. به‌کارگیری افزودنیهای شیمیایی مانند سیمان از رایجترین روشهای بهبود خصوصیات مهندسی خاک است که به فراوانی مورد استفاده مهندسان ژئوتکنیک قرار میگیرد. از سویی دیگر، تولید این مادهی پرمصرف موجب انتشار 8 درصد از دی اکسید کربن ورودی به جو زمین در بخش فعالیتهای انسانی میشود. بنابراین، درنظرگرفتن رویکردی برای کاهش مصرف سیمان امری ضروری تلقی میشود. یکی از راه‌های کاهش مصرف سیمان در روش تثبیت، استفاده از مواد پوزولانی طبیعی مانند زئولیت بوده؛ به طوری که بخشی ازسیمان را می‌توان با این مواد جایگزین نمود. از طرفی، افزودن مواد پوزولانی به خاک علاوه بر ارتقاء بسیاری از خواص مقاومتی، موجب بروز رفتار ترد و شکننده در هنگام گسیختگی هنگام بارگذاری در نمونههای تثبیت‌شده میگردند. بنابراین، افزودن الیاف طبیعی مانند کنف می‌تواند انتخاب مناسبی جهت برطرف کردن این مشکل روش تثبیت شیمیایی خاک‌ها باشد. در این پژوهش پس از انجام آزمایش‌های مقاومت فشاری محصور‌نشده برای دست‌یابی به درصد بهینه ترکیبات ماسه، سیمان، زئولیت و الیاف کنف، به بررسی رفتار برشی مستقیم نمونه‌های بهسازی شده پرداخته شد. با توجه به نتایج میتوان بیان نمود که افزودن 1% الیاف کنف با طول 1 سانتیمتر موجب حاصل‌شدن بهترین خواص مقاومتی در نمونه‌های تثبیت‌شده میگردد. بیشترین مقاومت در نمونه‌ با 8% سیمان و جایگزینی 30% سیمان با زئولیت حاصل گردید.
کلیدواژه‌ها

موضوعات


عنوان مقاله English

The effect of hemp fibers on unconfined compressive strength and direct shear parameters of sand improved with cement, zeolite

نویسندگان English

Iman Mirzadeh 1
Reza Shirinabadi 2
ghodratollah Mohamadi 3
Sayed Hamid lajevardi 4
1 Phd Student, Department of Civil Engineering, Engineering Faculty, South Tehran Branch, Islamic Azad University, Tehran, Iran
2 Associate Professor, Department of Civil Engineering, South Tehran Branch, Islamic Azad University, Tehran, Iran
3 Assistant Professor, Department of Civil Engineering, Engineering Faculty, South Tehran Branch, Islamic Azad University, Tehran, Iran
4 Associate Professor, Department of Civil Engineering, , Engineering Faculty, Arak Branch, Islamic Azad University, Arak, Iran
چکیده English

One of the essential difficulties in the field of foundation construction in construction projects is the low resistance of the subsoil, the presence of voids, and the presence of water in these holes in an undesirable amount, and this is the problem in the soil of the coastal area, which is more of the type of windy sand or loose sand. and is saturated; It causes many problems for engineers. Various methods are used in soil improvement according to the project's economic, operational, and environmental conditions. Considering the high adaptability of the chemical stabilization method to the different conditions governing the projects, it is considered one of the most common ways of soil improvement. Using chemical additives such as cement is one of the most common methods of improving soil engineering properties, which geotechnical engineers often use. On the other hand, the production of this highly consumed substance causes the release of 8% of the carbon dioxide entering the atmosphere in human activities. Therefore, considering an approach to reduce cement consumption is considered essential. One of the ways to reduce cement consumption in the stabilization method is to use natural pozzolanic materials such as zeolite So that part of the cement can be replaced with these materials. Therefore, adding natural fibers such as hemp can be a suitable choice to solve this problem of chemical stabilization of soils. This research investigated the direct shear behavior of improved samples after conducting unconfined compressive strength tests to achieve the optimal percentage of sand, cement, zeolite, and hemp fiber compounds and, according to the results, adding 1% of hemp fibers with a length of 1 cm results in the best resistance properties in the stabilized samples. The highest resistance was achieved in the sample with 8% cement and replacing 30% cement with zeolite.

کلیدواژه‌ها English

Hemp Fibers
Unconfined Compressive Strength
Zeolite
Cement
Sand Soil
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  • تاریخ دریافت 16 بهمن 1402
  • تاریخ بازنگری 18 آذر 1403
  • تاریخ پذیرش 26 اسفند 1402