تأثیر انتشار امواج حجمی مایل بر پاسخ سینماتیکی شالوده های نواری صلب بر روی توده نیمه بینهایت خاک به کمک روش المان مرزی

نوع مقاله : مقاله کامل پژوهشی

نویسندگان

1 گروه مهندسی عمران، دانشکده فنی و مهندسی، دانشگاه مراغه

2 گروه مهندسی عمران، دانشکده مهندسی عمران، دانشگاه ارومیه

10.22034/ceej.2024.60394.2325

چکیده

تحلیل لرزه ­ای شالوده­ ها از جمله مسائل مطرح در مهندسی ژئوتکنیک لرزه ­ای بوده و بدین‌منظور دو روش کلی پیشنهاد می‌­شود. در روش مستقیم، کل سازه و شالوده به­ همراه خاک بستر مدل­سازی شده اما در روش زیرسازه، پاسخ ­های شالوده و سازه به­ صورت گام ­به گام محاسبه گردیده و تأثیر سختی و جرم اجزای مختلف سازه و همچنین شالوده مورد بررسی قرار می­گیرد. در این مقاله، پاسخ لرزه‌ای شالوده‌های سطحی نواری تحت امواج ورودی هارمونیک مایل حجمی SV. P و SH به ­کمک روش المان مرزی مورد بررسی قرار می‌گیرد. بدین­ منظور در ابتدا، توابع امپدانس (Impedance Functions) شالوده‌‌های نواری واقع بر توده بی­نهایت خاک با روش المان مرزی و استفاده از المان‌های سه ­گرهی کوادراتیک (Quadratic) محاسبه می‌شوند. توابع امپدانس محاسبه شده به فرکانس، عرض شالوده‌ نواری، سرعت موج برشی و نیز ضریب پواسون توده خاک بستگی دارند. در ادامه، شالوده‌ نواری تحت اموج حجمی SV. P و SH  تحت زوایای مختلف قرار گرفته و با درنظر گرفتن پاسخ میدان آزاد و استفاده مجدد از روش المان مرزی، حرکت ورودی به شالوده‌ به ­دست می‌آید. مشاهده می­شود که پاسخ شالوده در فرکانس بی­ بعد 3، نسبت به پاسخ میدان آزاد و برای مؤلفه افقی موج SV و SH نیز برای مؤلفه قائم موج P در زاویه 𝛉=30o به ­ترتیب %41، %38 و 20% کاهش پیدا می­ کند. همچنین به ­عنوان مثالی در حوزه زمان، پاسخ شالوده نواری سطحی به یک موج مایل SV با تغییرات در قالب موج ریکر (Ricker wave) به‌کمک الگوریتم FFT تحلیل گردید.

کلیدواژه‌ها

موضوعات


عنوان مقاله [English]

The Influence of Volumetric Inclined Waves Propagation on The Kinematic Response of Rigid Strip Footings Resting on A Semi-Infinite Soil Mass Using Boundary Element Method

نویسندگان [English]

  • Forough Ashkan 1
  • Abbas Eslami Haghighat 2
1 Faculty of Civil Engineering, University of Maragheh, Maragheh, Iran
2 Faculty of Civil Engineering, University of Urmia, Urmia, Iran
چکیده [English]

Seismic analysis of foundations is one of the key problems in geotechnical earthquake engineering. For this purpose, two general methods are proposed. In the direct method, the entire structure, foundations and subgrade are modeled in one step. But, in substructure method, the contribution of stiffness and mass of foundations in the analysis are considered separately. In this paper, the seismic response of strip surface footings under volumetric oblique incident waves SV, P and SH is investigated using boundary element method. For this purpose, at first, the impedance functions of the strip footing located on the semi-infinite soil mass are calculated using boundary element method with three-node quadratic elements. The calculated impedance functions depend on the frequency, the width of the strip footing, the shear wave velocity and the Poisson’s ratio of the soil mass. The input motion of strip footing which is subjected to volumetric inclined SV, P and SH waves are then obtained by using free field motion and the boundary element method. It can be seen that the displacement response of the foundation at the dimensionless frequency of 3, compared to the horizontal component of the free field motion of SH and SV waves as well as vertical component of P wave at angle of θ=30° are reduced 41%, 38% and %, respectively. By the way, as an example in time domain, the response of surface strip footing due to inclined SV wave with Ricker waveform is analyzed utilizing FFT algorithm.

کلیدواژه‌ها [English]

  • Boundary element method
  • Kinematic soil structure interaction
  • Rigid strip foundation
  • Impedance functions
  • Foundation input motion
  • Volumetric waves
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