بررسی رفتار تناوبی خاک‌های ماسه‌ای لای‌دار با استفاده از آزمایش برش ساده سیکلیک در شرایط حجم ثابت

نوع مقاله : مقاله پژوهشی

نویسندگان

1 کارشناس ارشد مهندسی عمران-ژئوتکنیک، دانشکده فنی مهندسی، دانشگاه بین المللی امام خمینی (ره)، قزوین، ایران

2 مدیر گروه مهندسی عمران، دانشکده فنی و مهندسی،دانشگاه بین المللی امام خمینی - قزوین، ایران

چکیده

بررسی رفتار تناوبی خاک‌های ماسه‌ای در حین اعمال بار زلزله، یکی از مهم‌ترین موضوعات ژئوتکنیکی در دهه‌های قبلی بوده است و همچنان یکی از چالش برانگیزترین جنبه‌های ژئوتکنیک لرزه‌ای در میان محققین می‌باشد. در شرایط زلزله خاک تحت تنش نرمال ثابت اولیه قرار دارد و تنش‌های برشی در اثر زلزله روی نمونه مرتب تغییر جهت می‌دهد و در نتیجه جهت‌های تنش‌های اصلی مؤثر بر نمونه خاک به ‌طور تناوبی تغییر می‌یابد که این شرایط توسط دستگاه برش ساده قابل دستیابی می‌باشد. در این تحقیق، پاسخ‌های برش ساده تناوبی برای ترکیبات مختلفی از خاک ماسه تمیز سیلیکاتی و ریزدانه غیر خمیری لای به ‌منظور درک درستی از این گونه خاک‌ها مورد ارزیابی قرار گرفته است. آزمایش‌ها در نسبت تنش تناوبی برابر با 0/15 ( 0/15 = CSR) و فشار همه‌ جانبه 50، 100 و 150 کیلو پاسکال انجام گرفته است. آزمایش‌های برش ساده تناوبی حجم ثابت بر روی نمونه‌های ماسه تمیز نشان داده‌اند که با افزایش ریزدانه‌ی غیر خمیری تا 30 درصد وزنی نمونه، کرنش برشی کاهش و بعد از این درصد کرنش برشی افزایش می‌یابد اما کرنش برشی خاک ماسه با 40 درصد لای کمتر از ماسه خالص می‌باشد. نتایج نشان دادند، مقاومت روانگرایی خاک ماسه تمیز در شرایط یکسان بالاتر از خاک ماسه لای‌دار می‌باشد. همچنین با افزایش فشار همه‌ جانبه مقاومت روانگرایی خاک در تمامی درصدهای لای افزایش می‌یابد.

کلیدواژه‌ها

موضوعات

عنوان مقاله [English]

Investigation of Cyclic Behavior of Silty Sand Soils Using Cyclic Simple Shear Test Under Constant Volume Conditions

نویسندگان [English]

  • elahe khavaninzadeh 1
  • Reza Ziaei Moayed 2
1 Masters geotechnical engineering, Department of civil engineering in Imam Khomeini International university, Qazvin, Iran
2 Department of Civil Engineering in Imam Khomeini International university, Qazvin, Iran
چکیده [English]

The study of the cyclic behavior of sandy soils during seismic loading has been one of the most important geotechnical issues in previous decades and is still one of the most geotechnical challenging aspects among researchers. In the earthquake, the soil is under initial constant normal stress and the shear stresses change direction regularly; as a result, the directions of main effective stresses on the soil sample are changed. In the present study, cyclic simple shear responses for different mixtures of clean silica sand and non-plastic silt have been evaluated. The laboratory experiments were performed at a constant cyclic stress ratio of 0.15 (CSR = 0.15) and effective confining pressures of 50, 100 and 150 kPa. A series of constant volume cyclic simple shear tests on silty sand samples have shown that by increasing the non-plastic fines up to 30%, the shear strain decreases and then with an increment of silt content to 40% the shear strain increases, but the shear strain of the sand with 40% silt is less than the clean sand. The results also indicate that the liquefaction resistance of clean sand under the same conditions is higher than that of silty sand specimens. Also, with increasing the confining pressure, the soil liquefaction resistance increases in all silt percentages.

کلیدواژه‌ها [English]

  • Cyclic behavior
  • Simple shear tests
  • Non-plastic silt
  • Volume constant
  • Shear strain

مراجع

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نشریه مهندسی عمران امیرکبیر
دوره 54، شماره 6
شهریور 1401
صفحه 2189-2200

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