اداره کل اموال و املاک، بنیاد مستضعفان انقلاب اسلامی، گیلان، ایران

نوع مقاله : مقاله پژوهشی

نویسندگان

1 دانشکده فنی و مهندسی، دانشگاه قم، قم، ایران

2 اداره کل اموال و املاک، بنیاد مستضعفان انقلاب اسلامی، گیلان، ایران

چکیده

گسترش روزافزون استفاده از سازه‌‌های میخکوبی شده در مناطق لرزه‌‌خیز، اهمیت تعیین پارامترهای دینامیکی و الگوی گسیختگی این سازه‌‌ها را جهت دستیابی یه یک تحلیل لرزه‌‌ای ایده‌‌آل مسجل می‌‌سازد. این در حالی است که به دلیل عدم در نظر گرفتن روش میخکوبی به عنوان یک روش پایدار‌‌سازی بلند مدت و همچنین نوظهور بودن برخی از انواع اِلمان میخ، تاکنون اقدامی جهت تعیین مدول برشی و نسبت میراییِ به عنوان دو پارامترِ دینامیکیِ سازه‌‌های میخکوبی شده و همچنین ارزیابی الگوی گسیختگی لرزه‌‌ای آن صورت نگرفته است. از این رو، در پژوهش حاضر تلاش شد تا با استفاده از آزمایش‌های میزلرزه و استفاده از تکنیک پردازش تصاویر (PIV) به بررسی اثر چیدمان و طول میخ‌ بر پارامتر‌های دینامیکی و الگوی‌ گسیختگی دیوارهای مسلح‌شده با میخ‌های مارپیچی پرداخته شود. نتایج نشان داد که استفاده از میخ‌های مایل به جای میخ‌‌های افقی راه حلی کارآمد برای افزایش مدول برشی در در دیوارهای مسلح شده با میخ‌‌های مارپیچی شناسایی شد بطوریکه کارایی این راه حل با استفاده از میخ‌های کوتاهتر در نیمه بالایی دیوارها، کاهش و در نهایت با افزایش طول میخ ها در سرار ارتفاع دیوار به حداقل می‌‌رسد. همچنین مشخص شد که اگرچه استفاده از میخ‌های مارپیچ به جای میخ‌های تزریقی باعث کاهش 25 درصدی میرایی دیوار می شود، اما می تواند راه حل خوبی برای افزایش سختی دیوارهای میخ کوبی شده باشد. ردیابی باند‌‌های برشی در مدلها توسط تکنیک پردازش تصاویر نشان داد که یک سهمی با نقطه‌‌ی عطف مشخص می‌‌تواند به عنوان سطح گسیختگی در دیوارهای میخ کوبی شده با میخ‌های مارپیچی در شرایط لرزه‌‌ای در نظر گرفته شود بطوریکه که ابعاد آن با افزایش طول و زاویه‌ کوبش میخ‌ها افزایش می‌یابد

کلیدواژه‌ها

موضوعات


عنوان مقاله [English]

Determination of Shear Modulus, Damping Ratio and Failure Pattern in Helical Soil-Nailed Walls

نویسندگان [English]

  • majid yazdandoust 1
  • Reza Mollaei 2
1 Department of Civil Engineering, University of Qom, Qom, IRAN
2 Mostazafan Foundation of Islamic Revolution, Real estate Properteis Administration ,Gilan, Iran
چکیده [English]

A series of shaking table tests were performed on reduced-scale models of helical soil-nailed walls (HSNWs) to evaluate the effect of the nail arrangement and nail inclination on the failure mechanisms and dynamic characteristics of the retaining structures under seismic conditions. The results of particle image velocimetry (PIV) showed that the potential failure surfaces in the helical soil-nailed walls was a parabolic one with an inflection point and the dimensions of failure wedge increased as the length and inclination of the nails increased. A combination of overturning and base sliding was identified as the predominant deformation mode in the HSNWs and that base sliding faded with an increase in the nail inclination. It was found that horizontal helical nails located in the lower half of the wall played a more effective role in reducing lateral displacement, but the opposite was true for HSNWs with inclined nails. The use of inclined nails instead of horizontal ones was found to be an efficient solution for increasing the shear modulus in HSNWs. The efficiency of this solution decreased with the use of shorter nails in the upper half of the walls and was eventually minimized by increasing the length of the nails across the wall height. It was found that, although the use of helical nails instead of grouted ones reduced wall damping, it could be a good solution for increasing the stiffness of the soil-nailed walls.

کلیدواژه‌ها [English]

  • Helical Soil-Nailed Wall
  • Failure Mechanism, Damping Ratio
  • Shear Modulus, Particle Image Velocimetry
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