برگزاری دفاعیه دکتری مهندس جابر ممقانیان
 |
مهندس جابر ممقانیان دانشجوی دوره دکتری این دانشکده گرایش مکانیک خاک و پی، 10 اردیبهشت‌ماه سال 98 از رساله خود تحت عنوان «رفتار شناسی دیوارهای خاک مسلح تحت تراوش با استفاده از سانتریفیوژ» در محل سالن کنفرانس دکتر عباس‌نیا با راهنمایی دکتر حمیدرضا رازقی و مشاوره دکتر ویژوانادهام (عضو هیأت علمی انستیتو تکنولوژی بمبئی - IIT Bombay) دفاع نمود. |
|
چکیده این رساله به شرح زیر می‌باشد: هدف این رساله بررسی عملکرد دیوارهای خاک مسلح ژئوسینتتیکی با مصالح خاکریز غیراستاندارد و با نمای پنل بتنی تحت تراوش است. به تعداد 6 آزمایش سانتریفیوژی در شتاب 40g با استفاده از دستگاه سانتریفیوژ انستتیتو تکنولوژی بمبئی (IIT Bombay، کشور هند) با طول بازوی 4.5 متر انجام شد. ارتفاع دیوار در ابعاد واقعی برابر با 10 متر بود. مصالح غیراستاندارد شامل یک ماسه سیلتی با %20 ریزدانه بود. تأثیر سختی مسلح‌کننده، زهکش دودکشی ماسهای، تعداد لایههای ژئوکامپوزیت و تأثیر زهکش دودکشی ژئوتکستایلی در این تحقیق مورد مطالعه قرار گرفت. ارتفاع دیوار، نوع خاک، طول و فاصله داری قائم مسلح کننده ها و نوع نمای دیوار ثابت در نظر گرفته شد. در این مطالعه لایه های ژئوکامپوزیت عملکرد دوگانه تسلیح و زهکشی را داشتند. رفتار مدل های دیوار با استفاده از حس گر های نشست سنج و فشارسنج های آب حفرهای در طول آزمایش مورد تحلیل و بررسی قرار گرفت. آنالیز تصاویر نیز برای بدست آوردن میدان جابجایی ها و کرنش ها استفاده شد. رایانامه جهت ارتباط با دانشجوی فوق: mamaghani [AT] iust.ac.ir |
| Centrifuge model study on the performance of geosynthetic reinforced soil walls with marginal backfill under seepage Abstract: The objective of this thesis is to investigate the performance of geosynthetic reinforced soil walls with panel facing using marginal backfill subjected to seepage. A total number of six centrifuge model tests were performed at 40 gravities using a 4.5 m radius large beam centrifuge facility available at IIT Bombay. In this study the marginal backfill had 20% fines. The effects of geogrid stiffness, chimney sand drain, number of geocomposite layers and chimney nonwoven geotextile drain were studied in this research. The wall height, soil type, geogrid length and spacing and facing type was kept constant. In this study, geocomposite layers played dual function of drainage and reinforcement. The behavior of wall models was monitored using displacement and pore water pressure transducers during centrifuge tests. Image analysis technique was also used to get displacement and strain fields. The results revealed that a geogrid reinforced soil wall with low stiffness geogrid and without any drain system experienced a catastrophic failure due to excess pore water pressure that developed in the reinforced and backfill zones at the onset of seepage. In comparison, a soil wall reinforced with stiff geogrid layers was found to perform effectively even at the onset of seepage. Provision of chimney sand drain effectively decreased pore water pressure not only at the wall toe but also at mid-distance from toe of the wall and thereby resulted in enhancing the wall performance under the effect of seepage forces. However, a local piping failure was observed near the toe region of the wall. Provision of geocomposite layers at the bottom portion of the wall improved the wall behavior. Further, inclusion of geocomposite layers up to the mid-height of the wall from bottom resulted in superior performance of the wall reinforced with geocomposite layers than geogrid reinforced soil walls by lowering phreatic surface effectively. The performance of reinforced soil walls with geocomposite layers was found to be superior than the geogrid reinforced soil walls with chimney sand drain. Application of chimney geotextile layer could not improve the wall behavior but caused a delay on the occurrence of general failure. For analysing further the observed behaviour of centrifuge model tests, stability and seepage analysis were conducted using SLOPE/W and SEEP/W software packages. A good compromise was found between the results of numerical analysis and observation made in centrifuge tests. The effect of number of geocomposite layers as well as its transmissivity was further analysed using parametric study. The results of parametric study revealed that the number of geocomposite layers plays a main role on the good performance of the geogrid reinforced soil walls with marginal backfill. Based on the analysis and interpretation of centrifuge test results, it can be concluded that marginal soil can be used as a backfill in reinforced soil walls provided, it has geogrid layers of adequate stiffness and/or proper geocomposite layers or chimney sand drain configuration. Keywords: Geosynthetics, Geosynthetic reinforced soil walls, Marginal fills, Centrifuge modelling, Geocomposite, Chimney drain, Seepage, Seepage analysis, Stability analysis. |
 دفاع نمود.
){kind=link}
 دفاع نمود.
&source=https://www.iust.ac.ir/files/site1/yekta_program/contents_images/56284.jpg){kind=link}