بررسی رفتار ترمومکانیکی مخلوطهای ماسه- بنتونیت سیمانی و غیر سیمانی

نوع مقاله : مقاله کامل پژوهشی

نویسندگان

1 گروه مهندسی عمران، دانشکده فنی و مهندسی، دانشگاه خوارزمی

2 گروه مهندسی عمران، دانشکده فنی و مهندسی ، دانشگاه خوارزمی

چکیده

تا کنون تحقیقات زیادی به منظور تعیین رفتار ترمومکانیک خاکهای ریزدانه صورت گرفته است. نتایج نشان می دهد که قرار گرفتن رس اشباع در دماهای بالا تا ˚C100 در طولانی مدت باعث تغییر در فشار آب حفره ای، مقاومت برشی، رفتار حالت بحرانی خاک و دیگر موارد می شود. معمولا از خاک های چسبنده برای پوشاندن مدافن زباله های هسته ای در اعماق زیاد زمین استفاده می کنند. تاثیر افزایش دما تا C100 روی رفتار وابسته به زمان خاک های رسی و امکان واکنش های شیمیایی و ایجاد ساختار در دراز مدت، ضرورت مطالعه در مورد تاثیر حرارت روی خاک های رسی دارای ساختار را نشان می دهد. در این تحقیق برای بررسی خصوصیات مخلوط ماسه- بنتونیت غیرسیمانی و سیمانی از قبیل فشار آب حفره ای، مقاومت برشی و رفتار در حالت بحرانی، بر روی نمونه های غیرسیمانی و سیمانی (3 درصد سیمان) در دماها و فشارهای دورگیر مختلف آزمایشات سه محوری تحکیم یافته زهکشی نشده انجام شد. سرعت بخشیدن حرارت به تحکیم خاک، افزایش تنش انحرافی و کاهش فشار آب حفره ای در دماهای ثابت و بیشتر از دمای محیط هنگام اعمال برش زهکشی نشده، افزایش و کاهش به ترتیب چسبندگی موثر و زاویه اصطکاک داخلی موثر و کاهش و افزایش شیب خط حالت بحرانی به ترتیب برای نمونه های غیرسیمانی و سیمانی با افزایش دمای مرحله تحکیم از نتایج این تحقیق می باشد.

کلیدواژه‌ها

عنوان مقاله [English]

Thermo-mechanical behavior of uncemented and cemented sand-bentonite mixtures in elevated temperatures

نویسندگان [English]

  • Seyed Nima MirMohammadi 1
  • Atena Shirasb 2
  • Amir Hamidi 1
1 School of Engineering, Kharazmi University, Tehran, Iran
2 School of Engineering, Kharazmi University, Tehran, Iran
چکیده [English]

Thermo-mechanical behavior of clays has been investigated in the past two decades because of increased interest in using clay as a buffer material in nuclear waste barriers. Many of researchers studied the thermo-mechanical behavior of clays to estimate their performance as buffers for nuclear waste containers [1-4].
At present, sand-bentonite mixture is expected to be the most appropriate as a buffer material of high-level radioactive waste products when they are disposed in the deep ground resting place [5]. The dry density of pure clays can be as low as 1.3 Mg/m3 when compacted in situ; however, by mixing sand with the clay, the attainable dry density can be increased. Additions of sand can also be expected to decrease the creep potential of the material, increase the thermal conductivity and improve soil strength properties. Moreover, compacted clay-sand mixtures may possess lower hydraulic conductivities [6].
The soil around nuclear waste repositories are subjected to elevated temperatures and their features change in long time. So response of the soil to coupled effect of pressure and temperature has been studied with more accuracy in last decades. This research tries to check the thermo-mechanical behavior of saturated sand-bentonite mixture in different temperatures and confining stresses during triaxial tests.

کلیدواژه‌ها [English]

  • Thermo-mechanical behavior
  • Saturated sand-bentonite mixture
  • deviatoric stress
  • cemented soil

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