شبیه‌سازی رفتار مکانیکی ماسه تیز گوشه سیمانته تحت آزمون فشار همه‌جانبه به روش اجزای مجزا

نوع مقاله : مقاله پژوهشی

نویسندگان

گروه مهندسی عمران، دانشکده مهندسی، دانشگاه فردوسی مشهد، مشهد، ایران

چکیده

تشکیل پیوند میان دانه‌های خاک به کمک عامل سیمانی باعث می‌شود تا خاک رفتاری متفاوت نسبت به خاک غیرسیمانته داشته باشد. در این پژوهش، با استفاده از شبیه سازی عددی به روش اجزای مجزا، تأثیر مقاومت پیوند بر روی رفتار مکانیکی خاک ماسه‌ای سیمانته در آزمون فشار همه‌جانبه بررسی شده است. برای شبیه-سازی پیوند، از یک مدل پیوند تماسی استفاده شده که در آن، مقاومت پیوند در برش و کشش یکسان است. شرایط تشکیل پیوند در این مدل پیوند تماسی، وجود تماس فیزیکی بین ذرات و حداقل همپوشانی آن‌ها است. در شبیه‌سازی آزمون فشاری همه‌جانبه، از سه مقاومت پیوند مختلف در تهیه نمونه‌ها استفاده شده و این نمونه‌ها تا سطح تنش 60 مگا‌پاسکال بارگذاری شده‌اند. نتایج نشان می دهد افزایش مقاومت پیوند باعث می‌شود تمایل نمونه سیمانته به تراکم یا کاهش نسبت تخلخل در مقایسه با نمونه غیرسیمانته، کاهش پیدا کند. همچنین، تنش مرتبط با نقاط تسلیم اولیه و ثانویه با افزایش مقاومت پیوند، افزایش یافته است. با بررسی شکست پیوند در طول آزمون مشاهده می‌شود که در فشار همه‌جانبه‌ای که تسلیم اولیه در نمونه‌های سیمانته رخ می‌دهد، شکست پیوند با نرخ شدیدتری اتفاق می‌افتد. نتایج این شبیه‌سازی نشان می‌دهد که سهم تنشی که پیوندها از کل تنش اعمالی تحمل می‌کنند، با افزایش کرنش حجمی، افزایش پیدا می‌کند. همچنین هرچه مقاومت پیوند نمونه بیشتر باشد، مقدار تنش تحمل شده توسط پیوندها افزایش پیدا می‌کند. در مطالعه حاضر، دقت و صحت نتایج شبیه‌سازی با مقایسه نتایج آزمایشگاهی نشان داده شده است.

کلیدواژه‌ها

موضوعات


عنوان مقاله [English]

DEM Simulation of Mechanical Behavior of Cemented Angular Sand under Isotropic Compression Test

نویسندگان [English]

  • Moin Alreza Ghandehari
  • Ehsan Seyedi Hosseininia
  • siavosh Hohari
Civil Eng. Department, Faculty of Engineering, Ferdowsi University of Mashhad
چکیده [English]

The mechanical behavior of cemented sand is different from that of uncemented sand because of the presence of bonds between particles. In this study, the effect of bond strength on the mechanical behavior of cemented sand under isotropic compression test is investigated by using a numerical method called as Discrete Element Method (DEM) in a two-dimensional space. DEM is a powerful numerical tool by which, each particle is considered as a rigid body, and the equilibrium condition is satisfied by applying accelerations and displacement along with applied forces from adjacent particles. The novelty of this study in comparison to similar works is to consider the angular geometry of particle shape rather than supposing circular. The particles are connected to each other To simulate the cementation agent. For the simulation of bonds, a bond contact model is defined by considering tension, compression, and shear strengths; the tension and shear resistance of bonds are assumed to be equal. In this model, it is essential for particles to have physical contact and overlap to consider that they are bonded to each other. For the simulation of isotropic compression tests, the samples are loaded isotropically up to 60 MPa under different stress levels. The results indicate that with an increase in the bond strength, the sample resists higher against volume reduction, and also, primary and gross yield stresses increase. Results show that when a cemented sample reaches the primary yield point, the rate of broken bonds increases. The pressure that is carried out by bonds increases as the volumetric strain augments. In this research, the results are validated by existing experiments in the literature.

کلیدواژه‌ها [English]

  • Cemented sand
  • Angular particles
  • Isotropic compression test
  • Discrete Element Method
  • Contact Model
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