بررسی آزمایشگاهی و عددی تاثیر استفاده از ستون سنگی مسلح به صورت منفرد، گروهی و هسته‌دار در بهسازی خاک ماسه بادی

نوع مقاله : علمی - پژوهشی

نویسندگان

1 دانشیار گروه عمران-ژئوتکنیک، دانشکده فنی و مهندسی، دانشگاه محقق اردبیلی، اردبیل، ایران

2 دانشجوی دکتری مهندسی عمران-ژئوتکنیک، دانشکده فنی و مهندسی، دانشگاه محقق اردبیلی، اردبیل، ایران

چکیده

ستون های‌ سنگی به عنوان یک روش بهسازی خاک، نشست خاک در اثر بارهای وارده را تا میزان قابل توجهی کاهش داده و ظرفیت باربری خاک را افزایش می‌دهد. افزودن غلاف ژئوتکستایل نیز تاثیر به‌سزایی در این‌رابطه دارد. در این مطالعه با مدلسازی عددی ستون‌های سنگی به‌کمک نرم‌افزار Plaxis 3‌D Foundation ، میزان نشست خاک ماسه ای سست بررسی شده و با استفاده از مدلسازی آزمایشگاهی، نتایج حاصله صحت‌سنجی شدند. به این منظور ستون سنگی منفرد در دو حالت بارش ماسه و متراکم مدلسازی شده و در ادامه جانمایی گروهی در داخل خاک مورد بررسی قرار گرفته است. همچنین تاثیر افزودن غلاف ژئوتکستایل در داخل ستون سنگی، به‌عنوان هسته‌ی مرکزی نیز بررسی شده است. به این منظور در مدل آزمایشگاهی، یک هسته‌ی مرکزی به قطر 6 سانتیمتر محصورشده با غلاف ژئوتکستایل، داخل ستون سنگی به قطر 10 سانتیمتر در دو حالت بارش ماسه و متراکم ایجاد شد. نتایج به دست آمده از مدلسازی آزمایشگاهی و عددی هم‌خوانی مناسبی نشان دادند. همچنین مشخص شد، افزایش تعداد و تراکم ستون‌ها می‌تواند ظرفیت باربری را افزایش دهد. افزودن هسته‌ی مرکزی نیز تاثیر زیادی بر افزایش ظرفیت باربری داشت. این امر به علت افزایش تنش همه‌جانبه وارده در قسمت‌های داخلی ستون سنگی است. نتایج نشان داد ستون سنگی به قطر 10 سانتیمتر ظرفیت باربری را نسبت به خاک غیرمسلح 36 درصد افزایش داد، در حالی که در ستون سنگی هسته‌دار با بارش ماسه و متراکم این مقدار به ترتیب 43 و 54 درصد می‌باشد. با ارزیابی تغییرشکل‌های ظاهری در ستون‌های سنگی پس از بارگذاری مشخص شد، افزایش تراکم و افزودن غلاف ژئوتکستایل به هسته‌ی مرکزی، بر روی تغییرشکل‌های ایجاد شده و جلوگیری از گسیختگی‌های موضعی ستون سنگی تاثیر قابل ملاحظه‌ای داشته و روند تغییرشکلها مطلوب تر می گردد.

کلیدواژه‌ها

موضوعات


عنوان مقاله [English]

The Experimental and Numerical Studies of Encased Stone Column Individually, in Group and Nucleated on Improvement of Loose Sandy Soil

نویسندگان [English]

  • Alireza Negahdar 1
  • Nader Fathololoumi 2
1 Associate Professor, Civil Engineering Department, Faculty of Engineering, University of Mohaghegh Ardabili, Ardabil, Iran
2 PhD Student, Civil Engineering Department, Faculty of Engineering, University of Mohaghegh Ardabili, Ardabil, Iran
چکیده [English]

The stone columns, as a method of soil improvement, significantly reduce soil settlement due to incoming loads and increase soil load-bearing capacity. Adding geotextile as a stone column encasement has a considerable impact on this relationship. In this study, the amount of loose sandy soil settlement was investigated by numerical modelling of stone columns with the Plaxis 3D Foundation software, and the results were validated by using laboratory modelling,. For this purpose, a single stone column was modelled in two modes of rainfall density and compacted states and continuously the group mode in the soil was investigated. Also, the effect of adding geotextile encasement to the inner part of stone column investigated as a central core. So, a 6 centimetre diameter of central core that surrounded with geotextile encasement has considered inside of a 10 centimetre diameter of stone column in both rainfall density and compacted state. The results of experimental and numerical modelling were well-matched with each other. Also, it was clear that the increasing of stone column number and compaction can enhance soil bearing capacity, considerably. The adding of central core has had considerable effect on soil bearing capacity, too. This is due to the increase of all-round stress in the interior of the stone columns. The results showed that the stone column with a diameter of 10 cm increased the bearing capacity compared to unreinforced soil by 36%, while in the stone column with central core in rainfall density and compacted states, this amount is 43% and 54%, respectively. Also by evaluation of appearance deformations in stone columns after loading showed that increasing the density and adding geotextile encasement to the central core has a considerable effect on the created deformations and prevention of local ruptures and the process of deformation becomes more favorable.

کلیدواژه‌ها [English]

  • Stone column
  • Experimental and Numerical Modeling
  • Geotextile Encasement
  • Nuclear Stone Column
  • Deformation
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