مطالعه آزمایشگاهی ظرفیت باربری شالوده دایره‌ای واقع بر سطح خاک دانه‌ای مسلح به ژئوگرید

نوع مقاله : مقاله پژوهشی

نویسندگان

1 دانشگاه آزاد اسلامی، واحد علوم و تحقیقات تهران، گروه مهندسی عمران، تهران، ایران

2 گروه مهندسی عمران، دانشکده مهندسی، دانشگاه فردوسی مشهد، ایران

چکیده

پژوهش حاضر به منظور بررسی اثر مسلح سازی بر ظرفیت باربری شالوده دایرهای واقع بر خاک دانه‌ای صورت گرفته ً است. بدین منظور، جمعا 7آزمایش بارگذاری صفحه بزرگ مقیاس بر روی صفحه دایرهای به قطر 300میلیمتر انجام گرفته و جهت آماده سازی نمونه‌ها از سیستم بارش پردهای متحرک که توسط 60آزمایش بارش کالیبره گردیده، استفاده شده است. در سیستم آزمایشگاهی طراحی و ساخته شده، جهت اندازه گیری فشار زیر شالوده از روش جدیدی استفاده شده است. در کلیه آزمایش‌های بارگذاری روی خاک مسلح به ژئوگرید، فقط از یک لایه مسلح کننده استفاده شده و اثر عمق این لایه از کف شالوده مورد بررسی قرار گرفته است. نتایج آزمایش‌ها نشان دادند که استفاده از ژئوگرید، سبب افزایش ظرفیت باربری شالوده دایرهای تا حدود 1/56برابر حالت غیرمسلح می‌گردد. به علاوه، با افزایش عمق لایه ژئوگرید (نسبت ،)u/DFشیب نمودار بار- نشست (سختی پی) کاهش می‌یابد. به ازای مقادیر ،u/DF< 0/67اثر این پارامتر (عمق بیبعد) بر ظرفیت باربری شالوده ثابت می‌گردد که این امر بیانگر تغییر مکانیزم عملکرد مسلح کننده و وقوع گسیختگی در توده خاک بالای لایه ژئوگرید است. همچنین، نتایج نشان می‌دهد که با افزایش فاصله از مرکز شالوده، مقادیر فشار نرمال وارد بر کف شالوده کاهش می‌یابد.

کلیدواژه‌ها

موضوعات

عنوان مقاله [English]

A Study on Bearing Capacity of Circular Footing Resting on Geogrid Reinforced Granular Soil

نویسندگان [English]

  • A. Tabaroei 1
  • S. Abrishami 2
  • E. Seyedi Hosseininia 2
  • N. Ganjian 1
1 Department of Civil Engineering, Science and Research Branch, Islamic Azad University, Tehran, Iran
2 Department of Civil Engineering, Faculty of Engineering, Ferdowsi University of Mashhad, Mashhad, Iran
چکیده [English]

This study has been conducted to investigate the effect of reinforcing on the bearing capacity of circular footing resting on granular soil. For this purpose, a total number of seven large-scale plate load tests were carried out on a circular plate with a diameter of 300 mm. In order to prepare specimens, a portable curtain rain system is used which is calibrated by 60 raining tests. In the current designed and developed experimental system, a new method is used to measure the normal pressure at footing base. In all loading experiments on soil reinforced with geogrid, only one geogrid layer is used and the effect of depth of this layer from footing base is investigated. The results showed that with provision of geogrid, the bearing capacity of circular footing increases up to 1.56 times of unreinforced mode. In addition, it is shown that by increasing the ratio of u/DF, the slope of load-settlement curve (stiffness) decreases. For values of u/DF>0.67, the effect of this parameter (dimensionless depth of geogrid) on bearing capacity of the footing is constant, which indicates that the reinforcing mechanism has been changed and the failure occurs at the upper soil mass (above the geogrid). Also, the results showed that with increasing of the distance from center of the footing, the value of normal pressure applied at footing base reduces.

کلیدواژه‌ها [English]

  • Plate Loading Test
  • Circular Footing
  • Geogrid
  • Bearing Capacity
  • Settlement

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نشریه مهندسی عمران امیرکبیر
دوره 50، شماره 5
آذر و دی 1397
صفحه 973-986

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