نشریه علوم زمین خوارزمی

نشریه علوم زمین خوارزمی

بررسی آزمایشگاهی و عددی تاثیر سربار و تراکم خاک بر مقاومت بیرون‌کشیدگی میخ در زمین‌های مسلح شده با میخ‌کوبی

نویسندگان
سعید هاشمی
جعفر بلوری بزاز
دانشگاه فردوسی مشهد
10.22034/KJES.2023.8.2.106251
چکیده
یکی از مسائل مهم مهندسی عمران در مناطق شهری، پایدارسازی جداره ­های قائم و شیب­ دار خاکی است. از تکنیک ­هایی که روز به روز در محیط­ های شهری داخل و خارج کشور به منظور پایدارسازی گودها، رواج پیدا نموده است، تکنیک میخ­کوبی می­ باشد. چال­ های حفاری معمولی تحت اثر بارهای وارده، حتی در اعماق کم، بارها ریزش نموده و از سرعت کار کاسته شده و تلفات جانی و هزینه­ های اقتصادی غیر قابل پیش ­بینی را موجب شده است. علاوه بر آن ریزش چال­ های حفاری از سوی دیگر موجبات سستی خاک و از دست دادن تراکم آن را فراهم می­ سازد که به طبع آن باعث تحمیل تغییر شکل بیشتر افقی و عمودی در سطح زمین می­ شود. این تحقیق ضمن معرفی این مشکل در گودبرداری­ های عمیق، با مدل­سازی آزمایشگاهی و نیز عددی بوسیله نرم افزار اجزاء محدود Plaxis 3D Foundation، به بررسی چگونگی تاثیر میزان سربار و تراکم خاک بر رفتار میخ­ ها می­ پردازد. مشاهده گردید در شرایط یکسان تراکم خاک، ظرفیت بیرون­ کشیدگی انواع میخ­ ها با افزایش فشار سربار اعمالی بر روی خاک، افزایش پیدا می­ کند. همچنین در شرایط یکسان فشار سربار اعمالی، ظرفیت بیرون­ کشیدگی میخ­ ها در اثر افزایش وزن مخصوص خشک خاک که افزایش تراکم خاک می­ باشد، افزایش خواهد یافت.
کلیدواژه‌ها
میخ کوبی
سربار
تراکم خاک
مقاومت بیرون کشیدگی میخ
مدل سازی آزمایشگاهی و عددی

عنوان مقاله English

Experimental and numerical investigation on the effect of overburden and soil compaction on nail pullout strength in earth reinforced with nailing

نویسندگان English

Saeed Hashemi
Jafar Bolouri Bazaz
Ferdowsi University of Mashhad
چکیده English

One of the most important issues in urban areas is the stabilization of vertical and sloping earth walls. Nailing technique used for slope stabilization, has become popular day by day in urban environments, around the world. Normal drilling wells, even at shallow depths, have collapsed many times when subjected to applied loads, resulting in reduced work progress, loss of life and unpredictable economic costs. On the other hand, the collapse of drilling holes causes to loosen the soil structure and reduce its density, which in turn causes more horizontal and vertical deformations to occur in the earth’s surface. This research, introduces the deep excavation stabilization with the aid of laboratory and numerical modeling and presents the effect of overburden and soil density on the nails behavior. It was observed that under the conditions of the same soil density, the pullout capacity of all types of nails increases with the increase of the overburden pressure applied on the soil. For example, by increasing the overburden from 0.2 to 0.5 kg/cm2, in a soil sample with a specific weight of 1.4 gram/cm3, it causes a 100% increase, and in a soil sample with a specific weight of 1.6 gram/cm3 causes a 150% increase in the nail pullout capacity. Also, under the same conditions of the applied overburden pressure, the pullout capacity of the nails will increase due to the increase in the specific dry weight of the soil, which is an increase in the density of the soil. In other words, by increasing the specific dry weight of the soil from 1.4 to 1.6 gram/cm3, by applying overburden of 0.2, 0.5, and 0.8 kg/cm2, the pullout capacity of the nail increases by 16, 35, and 40 percent compared to the initial state.

کلیدواژه‌ها English

Soil nailing
Overburden
Soil Density
Nail Pullout Strengh
Experimental and Numerical Modeling
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