ساخت دستگاه استوانه توخالی برای بررسی رفتار کششی خاک‌های رسی با نگاهی بر اثر شاخص خمیری

نوع مقاله : مقاله پژوهشی

نویسندگان

1 دانشیار دانشکده فنی، دانشگاه تهران

2 دانشیار دانشکده مهندسی عمران، دانشگاه صنعتی خواجه نصیرالدین طوسی

3 دانشکده مهندسی عمران، دانشگاه صنعتی خواجه نصیرالدین طوسی، تهران، ایران

چکیده

مقاومت کششی خاک در سازه‌های مختلف ژئوتکنیکی از جمله سدهای خاکی، بستر راه‌ها، بستر فرودگاه‌ها، مکان‌های دفن زباله و خاکریز پشت دیوارهای حائل دارای اهمیت است. برای بررسی رفتار کششی خاک‌ها آزمایش‌های مختلفی وجود دارد که هرکدام نقاط قوت و ضعف خود را دارند. یکی از روش‌هایی که می‌توان مقاومت کششی خاک را به صورت مستقیم و مشابه با شرایط واقعی خاک به‌دست آورد، دستگاه استوانه توخالی کششی است که به ندرت در زمینه بررسی مقاومت کششی مورد استفاده قرار گرفته است. در این تحقیق یک دستگاه استوانه توخالی با قابلیت اندازه‌گیری خصوصیات کششی خاک طراحی، ساخت و راه‌اندازی شد. این دستگاه قادر است تنش کششی را به طور یکنواخت به کل توده خاک اعمال نماید به طوری که تمرکز تنش در هیچ نقطه‌‌ای از نمونه رخ ندهد. پس از طراحی، ساخت قطعات و راه‌اندازی دستگاه، جهت بررسی نحوه عملکرد دستگاه آزمایش‌های صحت‌سنجی انجام پذیرفت. نتایج آزمایش تکرارپذیری نشان از عملکرد دقیق و مطلوب دستگاه دارد. همچنین در این تحقیق، اثر شاخص خمیری خاک رسی (کائولینیت) بر رفتار کششی آن‌ها مورد بررسی قرار گرفت. شاخص خمیری خاک‌ها 10 و 24 درصد انتخاب گردید. نتایج نشان می‌دهد که برای خاک‌های رسی با یک منشاء مشخص، با افزایش شاخص خمیری، مقاومت کششی افزایش و کرنش گسیختگی کششی کاهش پیدا می‌کند.

کلیدواژه‌ها

موضوعات

عنوان مقاله [English]

Construction of a New Hollow Cylinder Apparatus to Study the Tensile Behavior of Clay with Different Plasticity Indices

نویسندگان [English]

  • Abbas Ghalandarzadeh 1
  • Mahmood Reza Abdi 2
  • Leila Shafiei Chafi 3
1 Associate Professor, School of Engineering, Tehran University
2 Associate Professor, Faculty of Civil Engineering, K.N. Toosi University of Technology
3 Faculty of Civil Engineering, K.N. Toosi University of Technology, Tehran, Iran
چکیده [English]

Soil tensile strength is important in different geotechnical structures such as earth dams, roads, airports, landfills, and retaining walls. There are several experiments to study the tensile behavior of soils with different advantages and disadvantages. One of the methods used to investigate soil tensile behavior is tensile hollow cylinder apparatus, which has seldom been used. In this research, a hollow cylindrical device to measure the tensile properties of soil was built and operated. This device can apply tensile stress evenly to the entire soil sample so that stress concentration does not occur at any point in the sample.  After designing, manufacturing, and assembling the apparatus, validation tests were performed to ensure the device was operating well. The results of the repeatability tests show the accurate performance of the device. Also, in this study, the effect of plasticity index (PI) on the tensile behavior of kaolinite clay was investigated. Clayey soils with plasticity indices of 10 and 24% were selected. The results show that for clays with a similar mineral, the tensile strength increases and the tensile failure strain decreases with increasing the plasticity index.

کلیدواژه‌ها [English]

  • Tensile hollow cylinder test
  • tensile strength
  • clay
  • plasticity index

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