الگوی کشسان - خمیری یکپارچه توأمان خاک، بر اساس نظریه سطح پیرامونی در حالت اشباع و نیمه‌اشباع

نوع مقاله : مقاله پژوهشی

نویسندگان

1 دانشکده فنی و مهندسی، دانشگاه تربیت مدرس، تهران، ایران

2 دانشکده مهندسی عمران و محیط زیست، دانشگاه علوم و فناوری نروژ، تروندهایم، نروژ

چکیده

خاک‌ها در طبیعت به طور متغیر می‌توانند در شرایط خشک، اشباع و نیمه‌اشباع باشند. در پروژه‌های ژئوتکنیکی، به دلیل تغییر حالت خاک تحت اثرات محیطی باید هر سه حالت خاک در نظر گرفته شود. اکثر الگوهای کشسان – خمیری در مکانیک خاک برای شرایط اشباع توسعه داده شده‌اند. در این مقاله، الگوی یکپارچه در چهارچوب حالت بحرانی برای توصیف رفتار طیف وسیعی از خاک‌ها تحت بارگذاری یکنواخت در شرایط زهکشی‌ شده و زهکشی‌ نشده بر اساس نظریه سطح پیرامونی و قانون جریان ناهمراه ارائه شده است. به منظور شبیه‌سازی یکپارچه هر دو خاک رس و ماسه، از جمله رفتار انتقال حالت، در این الگو از قانون اتساع عمومی اصلاح شده استفاده شده است. در الگوی حاضر از دیدگاه تنش مؤثر استفاده شده که به راحتی هر دو حالت اشباع و نیمه‌اشباع خاک را از طریق فراسنج تنش مؤثر وابسته به مقدار مکش در نظر می‌گیرد. الگوی پیشنهادی اثر توأمان رفتارهای مکانیکی و نگهداشت آب را از طریق منحنی مشخصه خاک – آب وابسته به نسبت پوکی در نظر گرفته است. به منظور بهبود دقت و همگرایی الگو، روش انتگرال‌گیری عددی ضمنی جهت پیاده‌سازی الگو به کار گرفته شده است. با استفاده از داده‌های آزمایشگاهی موجود در ادبیات موضوع، نشان داده شده که پیش‌بینی‌های عددی الگو تطابق خوبی با نتایج آزمایشگاهی داشته است. نتایج نشان داد که الگوی پیشنهادی قادر به پیش‌بینی ویژگی‌های شاخص رفتاری طیف وسیعی از خاک‌ها، شامل رفتار انتقال هموار از حالت کشسان به خمیری، نرم ‌شوندگی و سخت ‌شوندگی تنش، اتساع کرنش و همچنین رفتار انتقال حالت است.

کلیدواژه‌ها

موضوعات

عنوان مقاله [English]

A Coupled Unified Elastoplastic Model of Soil, Based on Bounding Surface Theory in Saturated and Unsaturated States

نویسندگان [English]

  • Ramin Ostovari 1
  • Ehsan Taheri 1
  • Ali Ghoreishian Amiri 2
1 Rock Mechanics, Faculty of Engineering, Tarbiat Modarres university, Tehran, Iran
2 Civil and Environmental Engineering, Norwegian University of Science and Technology, Trondheim, Norway
چکیده [English]

Soils in nature can variably be in dry, saturated, or unsaturated conditions. In geotechnical projects, all three soil states must be considered, because soil states can be changed by environmental effects. The most elastoplastic models in soil mechanics were developed for saturated conditions. In this paper, a unified model, in a critical state framework is presented for describing the behavior of a large spectrum of soils under monotonic loading in drained and undrained conditions based on bounding surface theory and the nonassociated flow rule. To unify the simulation of both clayey and sandy soils, among phase transformation behavior, in this model, a modified general dilatancy rule is used. In the current model, an effective stress approach is used that can easily consider both saturated and unsaturated states through effective stress parameter dependent on suction value. The proposed model considered the coupling effect of mechanical and water retention behaviors using soil water characteristic curve dependent on void ratio. To improve model accuracy and convergence, an implicit numerical integration scheme is used to implement the model. Using the experimental data available in the literature, numerical model predictions were shown to be in good agreement with the experimental results. The results showed that the proposed model was able to predict the characteristic features of the behavior of a wide range of soils, including smooth transition behavior from elastic to a plastic state, stress softening and hardening, strain dilatancy, and also phase transformation behavior.  

کلیدواژه‌ها [English]

  • Unified Model
  • Saturated and Unsaturated Soils
  • Bounding Surface
  • Effective Stress
  • Hydromechanical Coupling Effect

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نشریه مهندسی عمران امیرکبیر
دوره 54، شماره 12
اسفند 1401
صفحه 4527-4550

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