مطالعه آزمایشگاهی و عددی ظرفیت باربری ستون‌های شنی شناور تکی مسلح شده با میله‌های فلزی عمودی

نوع مقاله : مقاله پژوهشی

نویسندگان

1 گروه مهندسی عمران، واحد اراک، دانشگاه آزاد اسلامی، اراک، ایران

2 دانشکده مهندسی عمران، دانشگاه تفرش، تفرش، ایران

3 دانشکده مهندسی عمران، دانشگاه تهران، تهران، ایران

4 استادیار، گروه مهندسی عمران، واحد اراک، دانشگاه آزاد اسلامی، اراک، ایران

چکیده

ستون‌های شنی ظرفیت باربری خود را با محصوریت محیطی ایجاد شده توسط خاک اطراف افزایش می‌دهند. در خاک‌های رسی بسیار نرم، مقدار این محصوریت معمولا به اندازه‌ی کافی برای توسعه ظرفیت باربری نمی‌باشد. به همین دلیل در این نوع خاک‌ها استفاده از ستون‌های شنی مسلح شده با ژئوسنتتیک متداول است. این مقاله قصد دارد استفاده از میله‌های فلزی عمودی را به عنوان جایگزین ژئوسنتتیک‌ها مورد بررسی قرار دهد. در این مطالعه آزمون‌های آزمایشگاهی در مقیاس کوچک بر روی ستون‌های شنی شناور به قطر 80 و 100 میلی‌متر به طول به ترتیب 400 و 500 میلی‌متر مسلح شده با میله‌های فلزی عمودی، همراه با مدل‌سازی عددی دو بعدی با استفاده از نرم‌افزار پلکسیس صورت گرفته است. نتایج نشان می‌دهد حالت‌هایی که در آن میله‌ها با سختی بیشتر آرایش یافته‌اند، تحمل بار بیشتری دارند. مسلح کردن طول کامل ستون در مقایسه با نصف طول آن بهبود بیشتری در ظرفیت باربری ستون شنی ایجاد می‌کند. در مراحل اولیه بارگذاری با توجه به تمایل مصالح شنی شکسته ستون به متراکمتر شدن، افزایش بیشتری در ظرفیت باربری ایجاد شده و در ادامه‌ی فرآیند بارگذاری به علت خمره‌ای شدن ستونها، افزایش در ظرفیت باربری کم است. همچنین نتایج مدل‌سازی عددی نشان می‌دهد در ستون‌های شنی شناور مسلح شده در طول کامل خود، ستون‌ها به داخل خاک رسی نرم نفوذ کرده و حالت گسیختگی از خمره‌ای شدن به لغزش تغییر یافته است.

کلیدواژه‌ها

موضوعات

عنوان مقاله [English]

Experimental and Numerical Studies on Load-Carrying Capacity of Single Floating Aggregate Piers Reinforced with Vertical Steel Bars

نویسندگان [English]

  • Mehdi Mohammad Rezaei 1
  • seyed hamid LAJEVARDI 1
  • Hamid Reza Saba 2
  • abas ghalandarzadeh 3
  • Ehsanollah Zeighamie 4
1 Department of Civil Engineering, Arak Branch, Islamic Azad University, Arak, Iran
2 College of Civil Engineering, Tafresh University, Tafresh , Iran
3 School of Civil Engineering, University College of Engineering, University of Tehran, Tehran, Iran
4 Department of Civil Engineering, Arak Branch, Islamic Azad University, Arak, Iran
چکیده [English]

The load-carrying capacity of the aggregate piers increases by circumferential confinement created by the surrounding soil. In soft clay soils, the amount of confinement is usually not sufficient to develop a load-carrying capacity. Because of that, it is practical to use geosynthetic reinforced aggregate piers in this type of soils. This paper intends to evaluate the use of vertical steel bars as an alternative for geosynthetics. In this study, some small-scale laboratory tests were performed on floating aggregate piers with diameters of 80 and 100 mm and a length of 400 and 500 mm, respectively reinforced with vertical steel bars. Moreover, two-dimensional numerical modeling using the Plaxis software was conducted. The results show that using bars with more stiffness leads to more increase in load-carrying capacity. Reinforcing the full length of the aggregate piers, compared to half-length, will further improve the load-carrying capacity of the aggregate piers. In the early stages, by applying the load, the stone aggregates tend to compress, so load-carrying capacity increases and by continuing this process, the tendency to the occurrence of lateral bulging is seen and due to the low resistance of kaolin clay to the bulging, the increase of load-carrying capacity is negligible. Also, numerical modeling results show that the floating aggregate pier penetrated into soft clay soil in the full-length case, and the failure state changed from bulging to slip.

کلیدواژه‌ها [English]

  • Experimental study
  • numerical modelling
  • aggregate pier
  • kaolin clay soil
  • vertical reinforcing steel bars

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نشریه مهندسی عمران امیرکبیر
دوره 52، شماره 7
مهر 1399
صفحه 1797-1816

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