اصلاح یک مدل رفتاری الاستو پلاستیک سخت‌شونده- نرم‌شونده کرنشی برای بتن پلاستیک

نوع مقاله : پژوهشی

نویسندگان

1 فردوسی مشهد

2 دانشگاه فردوسی مشهد

چکیده

بتن پلاستیک، بتنی با مقاومت کمتر، شکل‌پذیری بالاتر و نفوذپذیری کمتر از بتن معمولی، یکی از روش‌های مؤثر برای کنترل تراوش سازه‌های آبی احداث‌شده روی پی‌های آبرفتی تغییر شکل‌پذیر می‌باشد. با توجه به تفاوت‌های رفتاری بتن پلاستیک نسبت به بتن‌های معمولی، اکثر مدل‌های رفتاری پیشنهادشده برای بتن‌های معمولی، توانایی بسیار محدودی در شبیه‌سازی رفتار تغییرشکلی مصالح بتن پلاستیک دارند و در اکثر موارد مدل سادۀ مورکولمب را برای این مصالح درنظر می‌گیرند. از این‌رو تعیین یک مدل رفتاری مناسبی که بتواند رفتار تنش-کرنش و کرنش حجمی-محوری مصالح بتن پلاستیک را به‌طور مناسبی پیش‌بینی نماید ضروری می‌باشد. در این مطالعه با استفاده از یک سری نتایج آزمون‌های سه‌محوری زهکشی‌شده بر روی مصالح بتن پلاستیک، رفتار مصالح با یک مدل الاستوپلاستیک که ویژگی‌های رفتاری سخت‌شوندگی و نرم‌شوندگی کرنشی مصالح در آن درنظر گرفته می‌شود بااستفاده از برنامۀ تفاضل محدود FLAC2D شبیه‌سازی‌ شدهاست. بدین منظور با پیشنهاد توابع اصطکاک، چسبندگی و اتساع بسیج‌شدۀ ویژه‌ای برای مدل رفتاری مذکور، سطح تسلیم و پتانسیل آن به‌گونه‌ای اصلاح ‌شده‌است که قابلیت مناسبی در شبیه-سازی رفتار تنش-کرنش و کرنش محوری-حجمی بتن پلاستیک را در شرایط بارگذاری آزمون‌ سه‌محوری زهکشی‌شده داشته باشد. نتایج این شبیه‌سازی نشان می‌دهد، مدل رفتاری اصلاح‌شده کارایی بسیار مناسبی را در شبیه‌سازی رفتار مصالح بتن پلاستیک دارد.

کلیدواژه‌ها

عنوان مقاله [English]

A Strain Hardening/Softening Elasto-Plastic Constitutive Model for Plastic Concrete Materials

نویسندگان [English]

  • Masoud Mehmandoost Kotlar 1
  • Ali Akhtarpour 2
  • Morteza Salari 1
1 Ferdowsi University of mashhad
2 Ferdowsi University of Mashhad
چکیده [English]

In this research, the behavior of plastic concrete materials with a strain Hardening/Softening Elasto-Plastic constitutive model are investigated using FLAC software based on a series of drained triaxial test results. The constitutive model is based on the mobilized strength (friction and cohesion) and mobilized dilatation angle concepts. The results indicate that the assumed functions of modified mobilized friction angle and mobilized cohesion (The Yield function of the model) which are common for geotechnical materials, can predict stress-strain behavior with a sufficient accuracy. However, they cannot simulates the Volume changes due to dilation effects accurately, especially for plastic concrete with a relatively high stiffness and strength. Therefore, the potential function of the model is modified. The stress-strain and Volume strains that have been obtained from the modified model are in good agreement with the experimental data, especially for soft plastic concrete, as well as for hard plastic concrete in a low confining pressure.

کلیدواژه‌ها [English]

  • Elasto-Plastic Constitutive Model
  • Plastic Concrete
  • Strain Hardening/Softening
  • Triaxial Tests

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