ارزیابی بسامد طبیعی خاک در محل احداث پل های غیرهم سطح و مناطق مسکونی در حال توسعه شهر کرمان

نوع مقاله : مقاله پژوهشی

نویسندگان

1 فارغ‌التحصیل کارشناسی ارشد ژئوفیزیک- زلزله شناسی، دانشگاه تحصیلات تکمیلی صنعتی و فناوری پیشرفته، کرمان

2 استادیار ژئوفیزیک– زلزله شناسی، دانشگاه تحصیلات تکمیلی صنعتی و فناوری پیشرفته، کرمان

چکیده

یکی از مسائل مهم در رابطه با تخریب سازه­ها در هنگام وقوع زمین‏لرزه، رفتار خاک روی سنگ بستر است که به­عنوان اثر ساختگاه شناخته می­شود. با توجه به موقعیت شهر کرمان و قرارگیری آن در ایالت لرزه زمین­ساختی ایران مرکزی و شرق ایران و مجاورت آن با چندین گسل از جمله گلباف، سیرچ، نایبند و کوهبنان و همچنین توسعه روزافزون آن، انجام مطالعات به منظور کاهش خسارات زمین‏لرزه ضروری می‌باشد. در این مطالعه، داده‌های میکروترمور در 52 ایستگاه لرزه­سنجی سه­مؤلفه­ای برداشت شده است. جهت در اختیار داشتن داده­هایی با نوفه محیطی کمینه، تمامی برداشت­ها در بازه زمانی 24 تا 5 صبح صورت گرفته است. محدوده­های برداشت، مناطق در حال توسعه شهر کرمان و محل احداث چهار پل مهم در حال ساخت در این شهر را پوشش می‏دهد. با توجه به هدف مطالعه که در حقیقت برآورد بسامد طبیعی و شاخص آسیب‌پذیری زمین می‏باشد، میکروترمور‌های ثبت شده در ایستگاه‏های لرزه‏نگاری با استفاده از روش نسبت طیفی مؤلفه افقی به قائم (H/V) پردازش شدند. مقادیر بسامد در این مناطق بین 3/0 تا 2/1 هرتز تغییر می‌کند. بر اساس بسامد به‌دست‌آمده و مقایسه با جداول استانداردبرای خاک، تمامی ایستگاه‌ها در رده­ ساختگاهی I از نوع خاک سست قرار گرفته­اند. در نهایت، نقشه پهنه‌بندی بسامد و شاخص آسیب‌پذیری رسم شد. نتایج نشان می­دهد که شاخص آسیب­پذیری در محدوده­های طرح توسعه شهر کرمان زیاد می‏باشد.

کلیدواژه‌ها

عنوان مقاله [English]

Soil Natural Frequency Assessment for Planned Grade-Separated Junctions and Under-Development Areas in the City of Kerman

نویسندگان [English]

  • Fatemeh Jahanpoor 1
  • MohammadReza Sepahvand 2
  • Afsaneh Nasrabasdi 2
1 Graduated MSc. of Geophysics, Graduate University of Advanced Technology, Kerman, I. R. Iran.
2 Assistant Professor of Geophysics, Graduate University of Advanced Technology, Kerman, I. R. Iran.
چکیده [English]

One of the important issues in infrastructures' destruction by earthquake is the impact of soil on the bedrock, which is known as “site effect”. Considering the fact that city of Kerman is located in the tectonic seismic state of eastern Iran and is situated near the Golbaf, Koohbanan, Sirch and Nayband faults, it is essential to reduce the dangers of the earthquake. Moreover, one of the most important structures which will be damaged during an earthquake is urban bridges. Thus, in designing the bridges, the impact of earthquake and vulnerability of bridges in places in which earthquake is likely to occur must be taken into consideration. In this study, recorded microtremor data in 52 three-component seismometric stations have been used. To have data with minimum environmental noise, all the measurements were performed in time period of midnight to 5 am in the morning. In this paper, the microtremor data related to the developing areas in Kerman and the erection site of four important bridges which are under construction has been investigated. Considering the objective of the study, which is estimation of the natural frequency and the earth vulnerability index, the recorded microtremors in the seismometric stations were processed using spectral ratio of H/V horizontal to vertical components. Results showed that frequency values vary from 0.3 to 1.2 Hz. Based on the achieved frequencies and comparison to the standard tables, it has been concluded that all the stations are of the soft-soil type in site class I. Finally, the frequency zoning map and vulnerability indices were drawn. Results showed that vulnerability index is high in the developing areas of the city of Kerman

کلیدواژه‌ها [English]

  • Earthquake
  • Site effects
  • Microtremor
  • H/V method

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مهندسی زیر ساخت های حمل و نقل
دوره 3، شماره 3
آذر 1396
صفحه 97-114

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سابقه مقاله

  • تاریخ دریافت: 14 خرداد 1396
  • تاریخ بازنگری: 11 شهریور 1396
  • تاریخ پذیرش: 16 مهر 1396

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