ارزیابی ریزساختاری تثبیت حرارتی خاکهای مارنی؛ مطالعه موردی: مارن غرب بندرعباس

نوع مقاله : پژوهشی

نویسندگان

• محمد امیری
• مسعود دهقانی
• مائده پاپی

هرمزگان

10.22067/civil.v32i4.78213

چکیده

مارن­ها ازجمله نهشته ­های رسوبی هستند که به‌طورکلّی از کانی­های رسی و کربنات کلسیم به نسبت­های بین 35% تا 65% تشکیل‌شده‌اند. وجود کانی­های رسی در خاک­های مارن به مقدار قابل‌‌توجّهی در کاهش شاخص دوام و درنتیجه وارفتگی خاک مارن نقش دارد. ازاین‌رو، تثبیت خاک­های مارنی حائز ‌اهمّیّت است. از سوی دیگر، وجود کربنات به‌عنوان یکی از اجزای اصلی خاک­های مارنی در رفتار مهندسی خاک، به‌‌شدّت تأثیرگذار است. حرارت چه در حالت گذرا و چه در حالت پایدار موجب تغییر در مشخصات فیزیکی، مکانیکی و ریزساختاری خاک­ها به‌ویژه ‌خصوصیّات مهندسی خاک­های رسی می­شود. بر این اساس، هدف از این پژوهش بررسی تأثیر حرارت بر پارامترهای مقاومتی خاک­های مارنی از منظر ریزساختاری است. در پژوهش حاضر تأثیر حرارت بر فرایند رفتاری خاک مارنی با استفاده از آزمایش­های درشت­ساختار (مقاومت فشاری محدود نشده، حدود اتربرگ، دانه­ بندی، وارفتگی، جذب آب و انقباض خطی) و آزمایش­ های ریزساختاری (pH و پراش اشعه ایکس (XRD)) مورد ارزیابی قرار گرفته است. بدین منظور، نمونه­ها در معرض سطوح حرارتی (25 تا 900 ‌درجه سلسیوس) قرار گرفته است. آزمایش­ ها با تأکید بر تغییرات ریزساختاری خاک مارن در دماهای معیّن و تأثیر تغییرات حرارت بر ‌خصوصیّات مکانیکی و مقاومتی خاک از منظر ریزساختاری انجام شده است. بر اساس نتایج به‌دست‌آمده خاک­های مارنی در دمای 700 ‌درجۀ سلسیوس دارای بیشترین مقاومت فشاری به میزان 69/27 کیلوگرم بر سانتی­مترمربع و دوام در مقابل رطوبت هستند.

کلیدواژه‌ها

• مارن
• تثبیت حرارتی
• مقاومت فشاری

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عنوان مقاله [English]

Microstructure Evaluation of Thermal Stabilization Marls Case Study: Marl West Bandar Abbas

نویسندگان [English]

• Masud Dehghani
• maedeh papi

چکیده [English]

Marls are among sedimentary deposits that generally contain 35 to 65 percent of clay minerals and calcium carbonate. The presence of clay minerals in marls has significant effect on reduction of slake durability index of marls. Hence, marls stabilization is important. Furthermore, the presence of carbonate as one of the main components of marls has drastic influence on engineering behavior of soils. Heat, both in transient or constant forms, results in physical, mechanical and microstructural alternation of soils, especially the engineering properties of clay soils. Accordingly, the purpose of this study is to investigate the effect of heat treatment on strengthening parameters of marls, microstructural perspective. Impression of heat treatment on behaviors of marls, using macrostructure tests (Unconfined Compressive Strength, Atterberg Limit, Granularity, Slaking, Water Absorption and Linear Shrinkage) and microstructural tests (pH and X-ray diffraction) have been assessed. For this purpose, the specimens are exposed to heating surfaces (25 to 900 °C). examinations with emphasize on microstructural alternations of marls on specified temperatures and effect of temperature variations on mechanical and strengthening specifications of soil, have been conducted. According to the results, on 700°C marl soils have the best compressive strength of 27.69 Kg/cm2 and durability against moisture.
 

کلیدواژه‌ها [English]

• Marl
• Thermal Stabilization
• Compressive Strength
• XRD

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