ارزیابی اثرات حفر تونل بر پاسخ لرزه‌ای سطح زمین با استفاده از روش تفاضل محدود

نوع مقاله : مقاله پژوهشی

نویسندگان

1 گروه مهندسی عمران، واحد قزوین، دانشگاه آزاد اسلامی، قزوین، ایران

2 گروه مهندسی عمران، واحد قزوین، دانشگاه آزاد اسلامی، قزوین ایران

چکیده

با افزایش روز‌افزون جمعیت شهری و ایجاد مشکلات ترافیکی، لزوم استفاده از فضاهای زیرزمینی در بخش حمل‌ونقل اجتناب‌ناپذیر است. تحقیقات اخیر نشان داده‌است که پاسخ لرزهای سطح زمین بر روی تونلها، میتواند از حرکت میدان آزاد در طول زلزله متفاوت باشد و الگوی انتشار امواج لرزهای را تغییر دهد و باعث تغییر در پاسخ زمین و پی ساختمآن‌ها شود. با این حال تا کنون این تاثیرات در آییننامههای لرزهای برای طراحی سازههای سطحی لحاظ نشده‌است. در این تحقیق به روش تفاضل محدود با استفاده از نرم‌افزار FLAC 2D به بررسی اثرات حفر تونل بر روی تقویت امواج زلزله در سطح زمین پرداخته شده‌است. با مدل‌سازیهای عددی صورت گرفته، تاثیر سرعت موج برشی خاک تحت امواج هارمونیک با فرکانس و دامنه‌های متفاوت در دو حالت با حضور تونل و میدان آزاد بررسی شده‌است. نتایج بررسیها نشان میدهد که سختی خاک و پوشش تونل و هم‌چنین محتوای فرکانسی امواج، تاثیر بسزایی در پاسخ زمین میگذارد و میتواند حداکثر شتاب سطح زمین را در شرایط امواج هارمونیک تا حدود 3/1 و با اعمال شتاب‌نگاشت زلزله بم تا 7/1 برابر افزایش دهد. اثر حضور تونل تا فاصله 15 برابر شعاع آن بوده است و در فواصل بیشتر بیتاثیر میشود. ضرایب بدست آمده برای بزرگنمایی پاسخ زمین میتواند در پهنه‌بندی لرزهای مناطق شهری و برای طراحی لرزهای سازههای سطحی در محدوده تحت تاثیر تونل، مورد استفاده قرار گیرد

کلیدواژه‌ها

موضوعات


عنوان مقاله [English]

The Effects of Tunnel Excavation on the Seismic Response of Ground Surface Using Finite Difference Method

نویسندگان [English]

  • M.H. Khalaj Zadeh 1
  • M. Azadi 2
1 Department of Civil Engineering, Qazvin Branch, Islamic Azad University, Qazvin, Iran
2 Department of Civil Engineering, Qazvin Branch, Islamic Azad University, Qazvin, Iran
چکیده [English]

Increasing urban populations and creating traffic problems, the use of the underground spaces in the transportation is inevitable. Recent studies have shown that seismic response of ground on tunnels can differ from free field movement during earthquake and change the model of propagation of seismic waves. However, these effects have not been used in the seismic standards for the design of surface structures. In this research, using the finite difference method and FLAC 2D software, the effects of tunneling on earthquake amplification on the surface has been studied. For this purpose, the variation of the shear wave velocity of the soil under harmonic waves by different frequencies and amplitudes in both forms of the presence of a tunnel and in the free field have been investigated. The results of the studies showed that soil hardness and frequency of waves have a significant effect on the site response, and can increase the acceleration of the surface in harmonic waves to about 1.3 and with the acceleration of the Bam earthquake to about 1.7 times. Whereas, the presence of tunnel does not affect at longer distances of 15 times its radius. The coefficients obtained the site response can be used in seismic zoning of urban areas and for the design of seismic structures in the area affected by the tunnel.

کلیدواژه‌ها [English]

  • Tunnel
  • Site Response
  • Finite Difference
  • Amplification of Seismic Waves
  • FLAC 2D
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