ارزیابی تاثیر طول حفره زیرسطحی بر انتشار امواج رایلی جهت شناسایی مرز دور و نزدیک حفره

نوع مقاله : علمی - پژوهشی

نویسندگان

1 استادیار، دانشگاه صنعتی شیراز

2 دانشجوی کارشناسی ارشد ژئوتکنیک گروه عمران و محیط‌زیست، دانشگاه صنعتی شیراز، شیراز، ایران

3 استادیار گروه مهندسی عمران، واحد شهرکرد، دانشگاه آزاد اسلامی،، شهرکرد، ایران

چکیده

شناسایی زیرسطحی در مواردی نیاز به آزمایشات لرزه‌ای دارد به خصوص زمانی که هدف، شناسایی ناهنجاری در محل مورد نظر باشد، شناسایی و تعیین ابعاد این ناهنجاری ها از این بابت مورد اهمیت است که ممکن است این حفرات دارای اندازه قابل توجه و در نزدیکی سطح زمین باشند و با اعمال بارگذاری و یا هر گونه تغییرات دیگری در محیط خاک موجب ایجاد خطرات جبران ناپذیری گردد. از روش های لرزه ای می‌توان جهت شناسایی قنات، اکتشافات معدنی، نفت و گاز نیز بهره گرفت. .با توجه به روش های گوناگون شناسایی ناهنجاری های زیرسطحی، در این مقاله از روش تحلیل چند ایستگاهی امواج سطحی استفاده شده است که بسیار سریع و مقرون به صرفه می باشد. در این راستا با شبیه سازی در محیط نرم افزار اجزا محدود اباکوس تاثیر ابعاد طولی حفره های کم عمق زیرسطحی مورد ارزیابی واقع شده است. حفره ها به طول های متفاوت در زیر سطح زمین قرار گرفته اند و میدان امواج در فضای زمان-فاصله و منحنی پراکندگی و نمودار ها در فضای فرکانس-فاصله بعد از فیلتر بررسی شده اند. نتایج به دست آمده در حوزه زمان-فاصله نشان دادند برای حفره به طول 2، 4، 6 و 8 متر امواج بازگشتی متناسب با افزایش طول حفره، از مرز دور و مرز نزدیک حفره با فاصله زمانی بیشتری از همدیگر منتشر می شوند و می توان مرز های طولی حفره را از طریق امواج بازگشتی با وضوح بیشتر بعد از فیلتر در حوزه زمان-فاصله و انرژی بیشتر در فضای فرکانس-فاصله شناسایی نمود.

کلیدواژه‌ها

موضوعات

عنوان مقاله [English]

Effect of subsurface cavity length on Rayleigh wave propagation to identify near and far boundary of the cavity

نویسندگان [English]

  • Hossein Rahnema 1
  • Mahmood Rasekh 2
  • Sohrab Mirassi 3
1 Assistant Professor, Department of Civil and Environmental Engineering, Shiraz University of Technology, Shiraz, Iran
2 M. Sc. Student, Department of Civil and Environmental Engineering, Shiraz University of Technology, Shiraz, Iran
3 Assistant Professor, Department of Civil Engineering, Shahrekord Branch, Islamic Azad University, Shahrekord, Iran
چکیده [English]

Subsurface identification in some cases requires seismic testing, especially when the goal is to identify anomalies at the site. Identifying and determining the dimensions of these anomalies is important because these cavities may be of considerable size and close to the ground. And cause irreversible risks by applying loading or any other changes in the soil environment. Seismic methods can also be used to identify aqueducts, mineral, oil and gas exploration. Due to various methods of identifying subsurface anomalies, in this paper, the multi-station surface wave analysis method is used, which is very fast and cost-effective. In this regard, by simulating in Abacus, finite element software environment, the effect of longitudinal dimensions of shallow subsurface cavities has been evaluated. The cavities are located at different lengths below the ground and the waves field in the time-offset and dispersion curves and graphs in the frequency-offset after the filter are examined. The obtained results in the time-distance showed that for a cavity with a length of 2, 4, 6 and 8 meters, the scattered waves are emitted from the far and near the face of the cavity with a longer time distance from each other in proportion to the increase in the length of the cavity. It can be concluded that the near and far boundary of cavity could be determined by using high resolution obtained data after filtering in time-distance domain, and more energy data in frequency-distance domain.

کلیدواژه‌ها [English]

  • Longitutal dimentions
  • Seismic waves
  • Rayleigh waves
  • Cavity
  • MASW
  • Disspersion curve
  • Wave field
  • F-K filter

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سابقه مقاله

  • تاریخ دریافت: 24 مرداد 1400
  • تاریخ بازنگری: 22 آبان 1400
  • تاریخ پذیرش: 04 آذر 1400

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