بررسی رفتار ماسه‌های آلوده به نفت خام در آزمایش CBR

نوع مقاله : مقاله پژوهشی

نویسندگان

1 دانشگاه رازی

2 دانشگاه رازی/دانشکده مهندسی/گروه عمران

3 گروه عمران/دانشگاه آیت اله بروجردی

چکیده

عوامل متعددی تحمل باربری خاکریزهای طبیعی و مهندسی را تحت تأثیر قرار می‌دهند، از جمله نشتِ نفت خام که منجر به کاهش مقاومت می‌گردد. هدف از این پژوهش آن است که با استفاده از آزمایش نسبت باربری کالیفرنیا (CBR)، مقدار افتِ باربری و رفتار تنش-کرنش برای خاک‌های ماسه‌ای آلوده به نفت خام بررسی گردد. در این تحقیق از 10 نوع ماسه‌ی مختلف با ویژگی‌های متفاوت استفاده شده است. روش کار بدین صورت است که یکسری آزمایش‌ CBR برای ماسه‌های تمیز (غیر آلوده) انجام می‌شود و سپس ماسه‌های آلوده به 6% نفت خام در شرایط و تراکم مشابه تحت آزمایش قرار می‌گیرند تا بتوان به صورت کمَی مقدار کاهش باربری ماسه‌های آلوده به نفت خام را به‌دست آورد. نتایج آزمایش‌ها نشان داد که باربری ماسه‌های آلوده به 6% نفت خام حداقل 50% نسبت به ماسه‌های تمیز کاهش می‌یابد و نمودارهای تنش-کرنش این خاک‌ها نیز شدیداً دچار کاهش خواهند شد. بر اساس نتایج به‌دست آمده در این پژوهش می‌توان بیان کرد که شکل ذرات (تیزگوشه بودن)، درصد درشت‌دانه‌ بودن ذرات در توده‌ی خاک و نوع دانه‌بندی عواملی هستند که در مقاومت ماسه‌های آلوده به نفت خام اثرگذارند. همچنین مشخص شد که ماسه‌ی استاندارد اتاوا دارای 83% کاهش مقاومت است و ماسه‌ی با ذرات تیزگوشه دارای کاهش مقاومتی در حدود 57% است. ماسه آلوده به نفت خام دچار افت شدید باربری می‌شود، ازین‌رو باید در مناطقی که خطر نشت نفت خام وجود دارد، در طراحی پی‌ها و سازه‌های مهندسی، ضرایب اطمینان بیشتری را در نظر گرفت.

کلیدواژه‌ها

موضوعات


عنوان مقاله [English]

The behavior of Oil-Contaminated Sands in CBR Test

نویسندگان [English]

  • Masoud Nasiri 1
  • mohammad hajiazizi 2
  • ahmad reza Mazaheri 3
1 Razi University
2 Razi University/Dep. of Engineering/Civil Eng.
3 Civl Eng./University of Ayatollah Borujerdi
چکیده [English]

Several factors affect the bearing of a load of natural and engineered embankments and slopes including the crude oil leakage, leading to a severe decrease in resistance. This is especially important for oil-rich countries, such as Iran, which have several crude oil resources. The main purpose of this study is to investigate the load-bearing (i.e., load versus settlement) and strain-stress behavior of crude oil contaminated sandy soils using the California bearing ratio (CBR) test. In this paper, 10 different types of sand with different characteristics were used. At first, a series of CBR experiments were performed for natural sands (i.e. clean sands) and then contaminated sands with 6% crude oil tested under similar conditions and densities to obtain the reduction in bearing a load of crude oil-contaminated sands quantitatively. Experimental results showed that bearing the load of sand containing 6% of crude oil decreased at least 50% compared to clean sands and the stress-strain diagram of these contaminated soils would decrease significantly. Based on the results of the investigation, it can be stated that particle shape (sharpness or roundness), coarse particle ratio, and finally the type of aggregation influences the resistance of crude oil contaminated sands. It was also found that standard Ottawa sand had an 83% reduction in strength and sand with a coarse particle had a 57% decrease in strength. Sand contaminated with crude oil experienced a severe loss of bearing capacity, so in designing foundations and engineering structures, greater safety factors should be considered, where there is a risk of crude oil leakage.

کلیدواژه‌ها [English]

  • Sand
  • Crude Oil
  • Bearing the load
  • California Bearing Ratio
  • Grain shape
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