بررسی اثر زلزله های دور و نزدیک بر رفتار لرزه‌ای گروه ریزشمع در خاک دانه ای سست و متراکم

نوع مقاله : مقاله پژوهشی

نویسندگان

1 دانشجوی کارشناسی ارشد ژئوتکنیک، دانشکده عمران، دانشگاه صنعتی شاهرود

2 عضو هیات علمی و رئیس دانشکده مهندسی عمران ، دانشگاه صنعتی شاهرود، شاهرود ، ایران

چکیده

مطالعه عملکرد سیستم ریزشمع‌ به عنوان یک روش موثر، اجرایی و مقرون به صرفه برای مقاوم‌سازی لرزه‌ای ساختگاه و فونداسیون و در نظر گرفتن ویژگی‌ها و اثرات متفاوت زلزله‌های حوزه دور و نزدیک بر سازه‌ها، ضرورت مطالعه عملکرد گروه ریزشمع تحت اثر زلزله‌های دور و نزدیک را توجیه می‌نماید. در این پژوهش با استفاده از نرم افزار Opensees، دو نوع خاک دانه‌ای سست (40% Dr=) و متراکم (80% Dr=) با رفتار الاستوپلاستیک و دو مدل تسلیح شامل گروه ریزشمع قائم و مایل با رفتار الاستیک و مصالح بتنی با توجه به سرعت موج برشی ساختگاه (Vs30) تحت اثر سه مجموعه زلزله دور و نزدیک قرار گرفت. پاسخ‌های گروه ریزشمع شامل تغییر مکان افقی، شتاب و نیروهای داخلی مورد بررسی و مقایسه قرار گرفت و نتایج مهم برای بهره‌گیری از گروه ریزشمع‌ به منظور مقاوم‌سازی لرزه‌ای در مناطق نزدیک به کانون لرزه‌زا و دور از آن ارائه گردید. نتایج نشان داد اثر رکوردهای نزدیک گسل موجب افزایش قابل ملاحظه تغییر مکان افقی به ویژه در ساختگاه دانه‌ای سست می‌گردد. افزایش تغییر مکان جانبی در اثر زلزله‌های نزدیک نسبت به زلزله‌های دور برای گروه ریزشمع قائم و مایل در ساختگاه دانه‌ای سست به ترتیب 125% و 124% و برای گروه ریزشمع قائم و مایل در ساختگاه دانه‌ای متراکم به ترتیب 15% و 13% می‌باشد. همچنین گروه ریزشمع مایل عملکردی تقریبا مشابه در کنترل شتاب و تغییر مکان‌های افقی و عملکرد بهتری در کنترل نیروهای داخلی نسبت به گروه ریزشمع قائم از خود نشان می‌دهد.

کلیدواژه‌ها

موضوعات

عنوان مقاله [English]

The effect of farfield and nearfield earthquakes on the seismic behavior of micropile group in loose and dense granular soils

نویسندگان [English]

  • Ehsan Mohamadi Esfahani 1
  • Reza Naderi 2
1 M.Sc. of Geotechnical Engineering, Department of Civil Engineering, Shahrood University of Technology
2 Civil Engineering Faculty Dean, Shahrood University of Technology, Shahrood, Iran
چکیده [English]

Studying the performance of micropile system as an effective, practical and affordable method for seismic retrofitting of the site and foundation and considering the different characteristics and effects of nearfield and farfield earthquakes on structures, justifies the need to study the performance of micropile group under nearfield and farfield earthquakes. In this research, using Opensees software, two types of loose (Dr =40%) and dense (Dr = 80%) granular soils with elastoplastic behavior and two reinforcement models including vertical and inclined micropiles with elastic behavior and concrete material were affected by three sets of farfield and nearfield earthquakes due to the shear wave velocity of the site (Vs30). The responses of the micropile group, including horizontal displacement, acceleration and internal forces, were studied and compared and important results were presented to use the micropile group in order to seismic retrofitting of areas close to and far from the epicenter. The results showed that the effect of near-fault records significantly increases the horizontal displacement, especially in the loose granular site. The increase in lateral displacement due to near earthquakes compared to far earthquakes is 125% and 124% for the vertical and inclined micropile group in the loose granular structure and 15% and 13% for the vertical and inclined micropile group in the dense granular site, respectively. Also, the inclined micropile group shows almost similar performance in controlling horizontal displacements and better performance in controlling internal forces than the vertical micropile group.

کلیدواژه‌ها [English]

  • Micropile group
  • Nearfield and farfield earthquakes
  • Finite elements
  • Time history analysis
  • Opensees

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نشریه مهندسی عمران امیرکبیر
دوره 54، شماره 4
تیر 1401
صفحه 1483-1502

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