1دانشیار؛ دانشکده‌ی مهندسی عمران، خاک و پی، دانشگاه تبریز
2دانشجوی کارشناسی ارشد؛ دانشکده‌ی مهندسی عمران، خاک و پی، دانشگاه تبریز
چکیده
در این مقاله به بررسی اثر وجود سازه‌های مجاور شامل ساختمان‌های شهری و یا تونل بر ارتعاشات ایجاد شده ناشی از ترافیک زیرزمینی پرداخته شده است. بدین منظور، از مدل‌های دو بعدی در حالت الاستودینامیک استفاده شده است. روش ترکیبی المان محدود و المان محدود مرزی مقیاس شده، برای مدلسازی بکار گرفته شده است. کاربرد روش مرز مقیاس شده در مدلسازی مساله ترافیک زیرزمینی در گذشته چندان رایج نبوده است. در این مقاله با استفاده از روش نوین مرز مقیاس شده، برای نخستین بار اندرکنش تونل-خاک-سازه مورد بررسی قرار گرفته است. نتایج به دست آمده نشان می‌دهد که ساختمان‌های مجاور تونل‌ها می‌توانند نحوه‌ی ارتعاش تونل را تحت تاثیر قرار دهند و باعث ایجاد ارتعاشات بیشتر در تونل‌ها شوند. همچنین برای حالت وجود دو تونل مجاور، وضعیت بحرانی یعنی عبور همزمان دو قطار مورد ارزیابی قرار گرفت و نشان داده شد که اگر چه وجود تونل مجاور سختی جانبی تونل موجود را افزایش می‌دهد اما عبور همزمان دو قطار باعث تشدید قابل ملاحظه‌ی ارتعاشات خواهد شد.
Analysis of train induced tunnel-structure interaction using the scaled boundary method
چکیده [English]
In this paper, train induced tunnel-structure interaction problem is analyzed using the coupled scaled boundary finite element (SBFE)-finite element (FE) method. Scaled boundary is a relatively novel method, which is capable of modeling bounded and unbounded domains accurately. Effects of adjacent buildings and effects of double tunnel on train-induced vibrations are evaluated.
Introduction
Construction and development of underground transportation lines like metro tunnels in urban areas is a suitable choice to reduce volume of the traffics especially in large cities. Train induced vibrations in these tunnels can be affected by adjacent structures. Train induced vibrations can make some damages in adjacent structures, and also, adjacent structures can affect vibrations of the tunnels. To analyze train induced vibration problems numerically, a special numerical method should be used to model unbounded soil media. Some of these methods are global and the others are local. Local methods cannot model radiation-damping effect of unbounded soil media completely and accurately. SBFE method is a global approach with semi-analytical formulation, which can model unbounded media precisely. In this paper, this novel approach is used to analyze tunnel- structure interaction problem.
Methodology and Approaches
In this paper, the coupled SBFE-FE method is used to model train-induced vibration in tunnels. The semi-analytical SBFE method is used to model unbounded soil media where conventional FE method is used to model near field soil media and contained structures. To use the mentioned coupled method, a MATLAB code is developed by the authors of this paper. The written code is verified by comparing its results with the results of the finite element-boundary element method presented in the relevant papers. As train induced vibrations cannot make large displacements, linear elastic behavior is considered for both soil and structures.
Results and Conclusions
It has been shown that adjacent buildings can make an increment on displacement time history of tunnels and it can reduce radiation-damping effect of the considered soil media. In the case of double tunnel, it is shown that adjacent tunnel can increase horizontal dynamic stiffness of the trapped soil between two tunnels. It is also demonstrated that the simultaneous movement of the second train can magnify the vertical displacements of the domain. In the case of the horizontal displacement, it is shown that the displacements of the domain between the two tunnels are decreased but the displacements of the other areas are magnified.
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