فصلنامه علمی کارافن

فصلنامه علمی کارافن

تأثیر ریزدانه‌های سیلت غیرپلاستیک و رس کائولین بر مقاومت برشی زهکشی‌نشده خاک ماسه‌ای تحت بارگذاری یکنواخت

نوع مقاله : مقاله پژوهشی (کاربردی)

نویسندگان
1 استاد، دانشکده فنی و مهندسی، گروه مهندسی عمران، دانشگاه ارومیه، ارومیه، ایران
2 دکترای عمران، دانشکده فنی و مهندسی، گروه مهندسی عمران، دانشگاه ارومیه، ارومیه، ایران.
چکیده
بیشتر رسوبات ماسه دارای مقادیر کم ریزدانه (رس و سیلت) هستند که تأثیرات پیچیده­ای بر رفتار زهکشی‌نشده ماسه­ها دارند. در این تحقیق تأثیر مقادیر کم ریزدانه (رس کائولین و سیلت فیروزکوه) بر رفتار زهکشی‌نشده ماسه­ با پنچ درصد ریزدانه (0، 3، 5، 7 و 10 درصد) بررسی می‌شود. بدین منظور 18 آزمایش زهکشی‌نشده فشاری با استفاده از دستگاه برش پیچشی استوانه­ای توخالی کنترل کرنش (HCA) روی ماسه فیروزکوه انجام می­شود. نمونه­ها در آزمایشگاه با روش ریزشی خشک با قیف تهیه شد و تحت دو تنش مؤثر اولیه 100 و 200 کیلو پاسکال تحکیم می­شوند. با افزایش مقدار ریزدانه سیلت تا 5 درصد مقاومت اوج ماسه افزایش می­یابد (حدود 5/18 درصد) و پس از آن با افزایش تا 10 درصد سیلت کاهش در مقاومت اوج (حدود 13 درصد) و افزایش در شاخص تردی و حساسیت به روانگرایی استاتیکی مشاهده می­شود. در حالی که افزودن ریزدانه رس کائولین، یک روند غالب نزولی در مقاومت اوج مشاهده می­شود (حدود 22 درصد کاهش در 10 درصد رس) و رفتار انقباضی افزایش می­یابد. این نتیجه را می­توان به ماهیت رس نسبت داد که تجمع ذرات رس در سطح تماس دانه­های ماسه منجر به ایجاد یک میکروساختار باز با اتصالات سست می­شود.
کلیدواژه‌ها
موضوعات

عنوان مقاله English

Effect of Non-plastic Silt and Kaolin Clay Fines on Undrained Shear Strength of Sandy Soils Under Monotonic Loading

نویسندگان English

Hadi Bahadori 1
Vahid Mohammadi 2
1 Professor, Department of Civil Engineering, Urmia University, Urmia, Iran.
2 PhD, Department of Civil Engineering, Urmia University, Urmia, Iran.
چکیده English

Most natural sandy deposits contain low amounts of fine content (clay and silt) that have complicated effects on the undrained behaviour of sands. In this research, the effect of low fine content (clay kaolin and Firuzkoh silt) on the undrained behaviour of sands with five percentages of fine grains (0, 3, 5, 7 and 10%) was investigated. For this purpose, 18 undrained compressive tests were carried out using strain control Torsional Shear Hollow Cylindrical Apparatus (HCA) on Firozkouh sand. The specimens were prepared in the laboratory by the Dry Funnel Deposition Method and consolidated under P'c= 100 and 200 kPa. By adding silt particles of up to 5%, the peak strength of the specimen increased (about 18.5%) and then by adding 5% of silt the peak strength decreased (about 13%) leading to an increase in the brittleness index and sensitivity to static liquefaction. With the addition of kaolin clay, a downward dominant trend in strength was observed (about 22% decrease in 10% clay) and the contractive behaviour increased. This result can be attributed to the nature of clay as the accumulation of clay particles on the contact surface of sand grains leads to the creation of an open microstructure with loose connections.

کلیدواژه‌ها English

Kaolin Clay
Firoozkuh Sand
Torsional Shear Hollow Cylindrical Apparatus (HCA) Contractive Behavior
Brittleness Index
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دوره 21، شماره 3
فنی و مهندسی
پاییز 1403
صفحه 415-437

  • تاریخ دریافت 22 اسفند 1402
  • تاریخ بازنگری 19 اردیبهشت 1403
  • تاریخ پذیرش 22 خرداد 1403