ارزیابی آزمایشگاهی ظرفیت باربری و نشست پی‌های باکت در خاک‌های روانگرا

نوع مقاله : یادداشت پژوهشی

نویسندگان

دانشکده مهندسی عمران، دانشگاه سمنان

چکیده

افزایش تقاضا برای انرژی باد در نواحی فراساحلی و گسترش استفاده از توربین‌های بادی فراساحلی در مناطق لرزه‌خیز، نیاز به توجه ویژه‌ای در انتخاب پی مناسب و شناخت رفتار آن دارد. وقوع روانگرایی در خاک‌های ماسه‌ای در مناطق لرزه­خیز، موجب خسارت­های سازه‌ای متعددی همانند نشست‌های اضافی و گسیختگی ناشی از کاهش ظرفیت باربری می‌شود. پی‌های باکت نوعی پی صندوقه‌ای مکشی نوین می­باشند که در طی دو دهه گذشته به‌عنوان فونداسیون توربین‌های بادی فراساحلی مورد استفاده قرار گرفته­اند. در این پژوهش، رفتار پی‌های باکت تحت بار قائم در خاک‌های روانگرا، با روش مدل‌سازی فیزیکی در شرایط تراوش رو به بالا مطالعه گردید. نتایج این تحقیق نشان می‌دهد در اثر افزایش فشار آب منفذی، ظرفیت باربری پی کاهش می‌یابد، اما حتی در شرایط روانگرایی کامل نیز پی‌ها دارای ظرفیت باربری قابل‌توجهی هستند. پی‌های باکت به دلیل لبه‌هایی که در اطراف دارند، تراکم خاک درون و زیر پی باکت را بهبود می‌بخشد. به همین علت، در شرایط روانگرایی پی‌های باکت در مقایسه با پی سطحی از افت ظرفیت باربری کم­تری برخوردارند. همچنین به دلیل وجود لبه‌ها در اطراف پی باکت، عملکرد پی در مقایسه با پی سطحی بهبود یافته و دامنه نشست کاهش می­یابد.

کلیدواژه‌ها


عنوان مقاله [English]

Experimental Investigation on the Behavior of Bucket Foundations Rested on Liquefiable Soils

نویسندگان [English]

  • Abdolhosein Haddad
  • Reza Amini Ahidashti
Faculty of Civil Engineering, Semnan University, Semnan, Iran
چکیده [English]

Wind turbines are installed in windy coastal and offshore regions to extract the wind energy with high efficiency (Barari et al. 2017). The construction cost of the foundation of offshore wind turbines is about 30% of the cost of all superstructure and foundations. Therefore, the economic design of the foundation is critically important and many researchers have focused on it. Offshore wind turbines are usually constructed on gravity-based or monopiles. Bucket foundations or skirted foundations are widely used in offshore regions, oil and gas industries. The use of bucket foundations has been increased in offshore regions especially for foundations of wind turbines over the past two decades (Byrne and Houlsby 2004; Eid, 2013). The behavior of tripod and pile foundations in liquefied soils was investigated. But there are limited reports and studies on the behavior of bucket foundation in liquefied soils (Yu et al., 2015). Conducted some centrifuge tests on wind turbine models with suction caisson foundations to study the behavior of bucket foundations in liquefied soils. It was found that increasing the foundation diameter and length of the skirt had the highest impact on the reduction of pore pressure. Moreover, an increase in the skirt length had the highest impact on the reduction of settlement.

کلیدواژه‌ها [English]

  • Bucket foundation
  • Liquefaction-induced settlement
  • Bearing capacity
  • Physical modeling
  • Upward seepage
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