بررسی آزمایشگاهی بالازدگی لوله‌ی مدفون در خاک مستعد روانگرایی در اعماق مختلف

نوع مقاله : مقاله پژوهشی

نویسندگان

دانشکده فنی و مهندسی، دانشگاه تبریز، تبریز، ایران.

چکیده

در زلزله‌های اخیر بسیاری از سازه‌های مدفون از جمله تونل‌ها و خطوط شریان حیاتی دچار آسیب جدی شده‌اند. قابل ذکر است که پدیده‌ی روانگرایی خاک، نقش پررنگی در به وقوع پیوستن این خسارات داشته است. خسارات ناشی از بالازدگی خطوط شریان حیاتی سبب ایجاد انگیزه‌ برای مطالعه‌ی بالازدگی سازه‌های مدفون گردیده است. بدین جهت در این پژوهش سعی بر آن شده است که بالازدگی لوله‌ی مدفون در خاک مستعد روانگرایی به صورت مدل‌سازی فیزیکی در اعماق مختلف مورد مطالعه قرار گیرد. خاک مورد استفاده در این مطالعه ماسه‌ی قوم تپه بوده و از میزلرزه به جهت شبیه‌سازی بار لرزه‌ای استفاده شده است. همچنین به سبب اهمیت مکانیزم تغییر شکل در این روند، از روش سرعت‌سنجی تصویری ذرات برای پی بردن به نحوه‌ی حرکت خاک اطراف لوله به هنگام روانگرایی، استفاده شده است. لوله‌ی مدفون در سه عمق: 1/5، 2/5 و 5 برابر قطر لوله، تحت بارلرزه‌ای قرار گرفته و میزان بالازدگی و مکانیزم تغییر شکل بررسی شده است. نتایج حاکی از آن است که با کاهش عمق مدفون لوله، با توجه به اضافه فشار آب حفره‌ای نسبتا بالا در عمق پایین‌تر خاک، اضافه فشار ایجاد شده بعد از بارگذاری دینامیکی تمایل به اتلاف دارد و به سمت نقاط کم فشار (قسمت سطح) جریان می‌یابند و چون در نواحی سطحی، جریان رو به بالاست بنابراین بالازدگی تا حدودی ادامه می‌یابد. همچنین حرکت بردارهای جابه‌جایی در طرفین لوله به شکل حلقه‌های دایروی شکل می‌باشد که سعی در بالازدگی لوله را دارند.

کلیدواژه‌ها

موضوعات

عنوان مقاله [English]

Experimental study of uplift of buried pipe liquefiable soil at different depths by shaking table

نویسندگان [English]

  • Sima Bahram Ghannad
  • Masoud Hajialilue Bonab
  • Maral Ghorbani Barazin
Department of Geotechnical Engineering, Faculty of Civil Engineering, University of Tabriz
چکیده [English]

Many buried structures, including tunnels and lifelines, have been severely damaged in recent earthquakes. It is noteworthy that the phenomenon of soil liquefaction has played a significant role in the occurrence of these damages. Damage caused by the uplift of lifelines has motivated the study of the uplift of buried structures. Therefore, in this study, an attempt has been made to the experimental study of the uplift of buried pipes in liquefiable soils by physical modeling at different depths. The soil used in this study is Gum Tape sand and shaking table has been used to simulate seismic load. Also, due to the importance of the deformation mechanism in this process, the particle image velocimetry method has been used to find out how the soil around the pipe moves during liquefaction. Buried pipe at three depths: 1.5, 2.5 and 5 times the diameter of the pipe has been subjected to seismic load and the degree of elevation and deformation mechanism have been investigated. The results show that with decreasing the buried depth of the pipe, due to the relatively high pore water pressure in the lower depth of the soil, the overpressure created after dynamic loading tends to be wasted and flows towards the low-pressure points (surface part). And because in the surface areas, the flow is upward, so the uplift continues to some extent. Also, the displacement vectors on the sides of the pipe are in the form of circular rings that try to raise the pipe.

کلیدواژه‌ها [English]

  • Liquefaction
  • Uplift
  • Buried pipe
  • Particle Image velocimetry
  • Physical Modeling

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نشریه مهندسی عمران امیرکبیر
دوره 54، شماره 1
فروردین 1401
صفحه 35-52

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