ارزیابی لنگر خمشی و جابجایی سازه های نگهبان طره ای در گودبرداری های عمیق

نوع مقاله: علمی - پژوهشی

نویسندگان

1 کارشناس ارشد مهندسی ژئوتکنیک، دانشکده مهندسی عمران و محیط زیست، دانشگاه صنعتی امیرکبیر، تهران، ایران

2 دانشیار، دانشکده مهندسی عمران و محیط زیست، دانشگاه صنعتی امیرکبیر، تهران، ایران

چکیده

در بسیاری از پروژه های گودبرداری به دلایل مختلف سازه‌های نگهبان طره ای تنها گزینه محسوب می شوند. لذا در این مطالعه با جمع آوری یک بانک داده گسترده شامل بیش از 300 سازه نگهبان از نقاط مختلف جهان، محدوده ضخامت و سختی رایج سازه‌های نگهبان طره ای شکل بررسی شده است. اعتبار سنجی رایج ترین روش برآورد لنگر خمشی در خاک های دانه ای (روش تعادل حدی) نیز نشان داد که این روش، فقط در دیوار صلب نتایج نسبتا دقیقی ارائه می‌دهد. لذا جهت تخمین دقیق‌تر، رابطه جدیدی برای محدوده سختی خمشی رایج ارائه شده است. لنگرهای خمشی برآورد شده با این رابطه برای 70 مدل اجزای محدود در محدوده 85% تا 115% برآوردهای روش اجزا محدود بود. براساس نتایج، در همه خاک‌های دانه ای به جز خاک‌های سست تا بسیار سست، می توان عمق بیش از 10 متر را با سازه های طره ای مهار کرد. اما در صورتیکه عمق گود بیش از 15 متر باشد صرفا در حالتی می توان از سازه های نگهبان طره ای رایج استفاده کرد که مدول الاستیسیته خاک بیشتر از حدود 70 مگاپاسکال باشد. همچنین بررسی‌ها نشان داد تاثیر سختی خمشی دیوارهای دیافراگمی در لنگر های خمشی کمتر از 2000 کیلونیوتن- متر قابل اغماض خواهد بود.

کلیدواژه‌ها

موضوعات


عنوان مقاله [English]

Evaluation of bending moment and deflection of cantilever supported excavations

نویسندگان [English]

  • Seyed Hamid Yasrebi 1
  • Abolfazl Eslami 2
1 MSc, Department of Civil and Environmental Engineering, Amirkabir University of Technology, Tehran, Iran
2 Associate Professor, Department of Civil and Environmental Engineering, Amirkabir University of Technology, Tehran, Iran
چکیده [English]

In many conditions, because of several restrictions, cantilever walls are the only way to stabilize the excavations. It is no doubt that one of the most important parameters in design of such walls is wall stiffness. Therefore, in this study, a large number of case histories are collected and the most commonly used range of wall thickness and stiffness are determined based on this database. In addition, validation of limit equilibrium method (LEM) in granular soils showed that this method can only estimate bending moment of rigid walls. Therefore, for more accurate estimating, a new equation is presented for the most commonly used range of wall stiffness and various types of granular soils. Moreover, LEM based equation is replaced with a modified version. The new equation was successfully validated using 70 numerical models and results lied in range of 85% to 115% times the predicted values obtained from FEM. According to the results, in loose and very loose soils, the common cantilever walls can only stabilize the excavations with depth less than 10 m. While if depth is more than 15 m, soil type should be dense or very dense with “E” more than about 70 MPa. The results also show that the effect of wall stiffness is negligible in bending moments less than 2000 kN.m.

کلیدواژه‌ها [English]

  • Cantilever Retaining Wall
  • Bending Moment
  • Deflection
  • Allowable depth
  • Wall stiffness
  • Granular soil

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