تحلیل حساسیت پاسخ GPR اهداف ژئوتکنیکی مدفون به پارامترهای هندسی و فیزیکی با استفاده از مدل‌سازی عددی پیشرو

نوع مقاله: مقاله پژوهشی

نویسندگان

1 دانشکده مهندسی معدن دانشگاه صنعتی اراک

2 دانشکده مهندسی معدن، دانشگاه صنعتی اصفهان

3 دانشکده مهندسی معدن، دانشگاه تهران

10.17383/S2251-6565(15)940912-X

چکیده

 
در پژوهش حاضر پاسخ GPRمدل­های مصنوعی مختلف متناظر با ساختارهای ژئوتکنیکی فرضی نظیر استوانه افقی منفرد، منشور دوبعدی، استوانه افقی جفت، چندضلعی دوبعدی دلخواه و زمین لایه­ای، با استفاده از مدلسازی عددی پیشرو به­روش تفاضل محدود دوبعدی حوزه زمان بهبود یافته در حوزه فرکانس، مدلسازی شده است. در این تحقیق براساس پارامترهای ریاضی هذلولی و نتایج مدلسازی پیشرو داده­های GPRهدف استوانه­ای، نشان داده شده که بین نسبت ارتفاع به پهنای هذلولی با پارامترهای هندسی هدف استوانه­ای (قطر و عمق دفن) یک سری روابط خطی وجود دارد. این روابط می­تواند به­عنوان معیارهای کمی مناسب برای شناسایی مشخصات فیزیکی و هندسی اشیاء استوانه­ای مدفون در زیر زمین با تصاویر GPR مورد استفاده قرار گیرد. برای دست­یابی به هدف و تحلیل حساسیت، تأثیر پارامترهای مختلف هدف نظیر شکل هندسی، جنس، اندازه و ابعاد، عمق دفن، نوع و سطح سیالات محتوی (درصد حجمی سیالات) و ویژگی­های فیزیکی محیط میزبان بر روی پاسخ­های GPR، مورد بررسی قرار گرفته است. نتایج حاکی از پتانسیل بالقوه روش GPR برای آشکارسازی انواع اهداف مدفون، شناسایی جنس مدل و ارزیابی ویژگی­های محتوای سیال مدل است. با استفاده از این شبیه­سازی­ها می­توان اهداف استوانه­ای فلزی را از غیرفلزی تشخیص داد و نوع سیال محتوای درون ساختارهای غیرفلزی (نظیر هوا، آب شیرین و آب شور) را تعیین نمود. نتایج تحقیق با مطالعه موردی برای شناسایی قنات واقع در دشت شاهین شهر اصفهان نیز اعتبارسنجی گردیده است، به­گونه­ای که عمق دفن و قطر قنات به­ترتیب با خطای 4/3 درصد و 12 درصد تقریب زده شد.

کلیدواژه‌ها

موضوعات


عنوان مقاله [English]

Sensitivity analysis of physical and geometrical parameters of geotechnical targets on GPR responses using forward modeling

نویسندگان [English]

  • Reza Ahmadi 1
  • Nader Fathianpour 2
  • Gholam-Hossain Norouzi 3
1 Dept. of Mining, Arak University of Technology
2 Dept. of Mining, Isfahan University of Technology
3 Dept. of Mining, University of Tehran
چکیده [English]

In the current research, GPR response of variety of synthetic models encountered with geotechnical applications containing single horizontal cylinder, 2D prism, double horizontal cylinders, 2D arbitrary polygon and layered earth have been produced using forward modeling through the finite-difference time-domain algorithm improved in the frequency domain. In this research by using the parameters of a hyperbola and GPR responses produced for cylindrical objects by means of the forward modeling, it was revealed that there exist some linear relationships between the hyperbola height to width ratio (H/W) with physical and geometrical parameters of the cylindrical objects. These relations can be used as proper quantitative criteria to identify physical and geometrical parameters of buried cylindrical objects on GPR images. To achieve this purpose, the effect of several parameters such as geometrical shape, material type, size and burial depth of the objects as well as type and interface of fluids content and host medium physical properties on GPR responses, have also been studied. The results lead us to the potential of GPR method to detect the kinds of targets; identifying the parameters of cylindrical objects and evaluating characteristics of fluid content, so that one can distinguish metallic from nonmetallic targets as well as type of fluid content of nonmetallic targets (i.e. air, fresh water and salt water). The results of the research were validated by applying for identification of buried qanat in Shahin-Shahr plain, Isfahan province. The burial depth and diameter of the qanat were estimated by 3.4% and 12% erorr respectively.



کلیدواژه‌ها [English]

  • Ground-Penetrating Radar (GPR)
  • Hyperbolic response
  • Numerical forward modeling
  • Geotechnical targets
  • sensitivity analysis
  • Geometrical parameters of cylindrical targets
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