مطالعه ناحیه سست شدگی و قوس زدگی خاک در تونل شهری مجاور زون ناپایدار

نوع مقاله : مقاله کامل پژوهشی

نویسنده

گروه مهندسی عمران، دانشکده مهندسی، دانشگاه صنعتی کرمانشاه

چکیده

در این مطالعه وضعیت گسترش زون سست ­شدگی در بالای تونل­ های نعل اسبی حفرشده در خاک لایه ­ای مورد مطالعه قرار گرفته است. تحلیل ­های اجزای محدود دو و سه ­بعدی به­ کار برده شده است. اثرات بیش تحکیم یافتگی، تغییرات ضخامت و محل استقرار لایه خاک ناپایدار در قالب مفهوم زون ناپایدار بر محدوده ناحیه سست­شدگی ارزیابی شده است. برای مدل­سازی لایه ­های خاک از مدل­ های رفتاری مور-کولمب MC و خزش خاک نرم SSC استفاده شده است. همچنین مقایسه نتایج تحلیل­ های عددی خمیری و تحکیمی ارائه شده است. نتایج این مقاله نشان می­دهد که ضخامت زون ناپایدار، میزان گسترش آن نسبت به موقعیت حفر تونل، وضعیت سربار ساختمانی در سطح زمین، نوع تحلیل خمیری یا تحکیمی و وضعیت بیش­ تحکیم یافتگی خاک به­ طورکلی هندسه زون سست­ شدگی در تاج تونل را تغییر می­ دهند. این تغییرات شامل اختلاف چشمگیر در ابعاد، الگو و میزان گسترش زون سست ­شدگی خاک است. همچنین نتایج تحلیل­ های اجزای محدود سه ­بعدی مابین 5 تا 35 درصد کمتر از نتایج تحلیل­ های محافظه­ کارانه اجزای محدود دوبعدی است.

کلیدواژه‌ها

موضوعات


عنوان مقاله [English]

Studying the area of soil loosening and arching in urban tunnels adjacent to unstable zones

نویسنده [English]

  • Yazdan Shams Maleki
Department of Civil Engineering, Kermanshah University of Technology (KUT), Kermanshah, Iran
چکیده [English]

In this study, the expansion of the loosening zone at the top of horseshoe tunnels bored in layered soil has been studied. Two and three-dimensional finite element analyzes have been used. The effects of over-consolidation, changes in thickness and location of the soft soil layer have been evaluated in the form of the unstable zone concept on the extent of the loosening zone. Mohr-Coulomb (MC) and soft soil creep (SSC) models have been used to model the soil layers. Also, the comparison of the numerical analysis results of the plastic and consolidation analyses is provided. The results of this article show that the thickness of the unstable zone, the extent of its expansion in relation to the tunnel digging position, the surface building surcharge condition, the type of plastic or consolidation analysis and the over-consolidation condition of the soil generally change the geometry of the loosening zone in the tunnel crown. These changes include significant differences in the dimensions, pattern and expansion of soil loosening range.

کلیدواژه‌ها [English]

  • Urban tunnel
  • unstable zone
  • soil creep
  • loosening zone
  • finite elements
  • two-dimensional and three-dimensional models
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