فشار خاک وارد بر مجاری جعبه ای مدفون در ترانشه به روش ترانشه ناقص تحت اثر فشار سربار

نوع مقاله: پژوهشی

نویسندگان

1 گروه مهندسی ژئوتکنیک، دانشکده عمران، دانشگاه تبریز، تبریز، ایران

2 گروه ژئوتکنیک، دانشکده عمران، دانشگاه تبریز، تبریز، ایران

3 دانشیار دانشگاه صنعتی اصفهان-دانشکده عمران

چکیده

طراحی مجاری جعبه‌ای مدفون تحت فشار سربار، نیاز به ارزیابی دقیق مقدار تنش‌های وارد بر وجوه مختلف مجرا دارد. چنانچه مجرا تحت فشار سربار بزرگ قرار داشته باشد، ارائه راهکاری به منظور کاهش مقدار تنش وارد بر جعبه حائز اهمیت می‌باشد. در این مطالعه، با ترکیب دو روش متداول دفن مجاری زیرزمینی (دفن در ترانشه و دفن در ترانشه ناقص)، روشی معرفی گردیده که بتوان مقدار تنش وارد بر وجوه مختلف را تحت کنترل قرار داده و آن‌را کاهش داد. به این منظور ابتدا، مدل‌سازی عددی مورد صحت‌سنجی قرار گرفته و سپس به مطالعه عددی اثر پارامترهای مختلف بر مقدار ضریب اندرکنش برای وجوه مختلف مجرای جعبه‌ای، تحت فشار سربار پرداخته شده است. تحلیل‌های عددی با استفاده از روش اجزاء محدود و به صورت دوبعدی انجام گرفته است. نتایج تحلیل‌ها نشان می‌دهد، توسعه قوس‌شدگی در خاکریز، عامل مهمی در کاهش مقدار تنش وارد بر سقف، دیواره و کف مجرای مدفون می‌باشد.

کلیدواژه‌ها

موضوعات


عنوان مقاله [English]

Investigation of applied earth load on buried box culverts in trenches using induced trench method under embankment pressure

نویسندگان [English]

  • Gholam Moradi 1
  • Ebrahim Hassankhani 2
  • Amir Mahdi Halabian 3
1 Civil Engineering Department, Associate Professor, Tabriz University, Tabriz, Iran
2 Civil Engineering Department, Ph.D candidate, Tabriz University, Tabriz, Iran
3 Associate Professor, Department of Civil Engineering, Technology University of Isfahan
چکیده [English]

Underground box culverts have applied to facilitate people's standard of living in various ways. Design and construction of these conduits request for determination of exerted pressure due to the soil and embankment weight above. Where, the applied load is large and culverts have been installed under high embankment, applied pressure become more significant. Therefore, reduction and control of the earth load on culverts, is of importance concern. Various methods and theories have been proposed to reduce the applied earth load on these underground structures. Among these, two methods have been commonly used namely, Trench Installation (TI) and Induced Trench Installation (ITI). For TI method, where the culvert is placed in a narrow trench, the deformable soil tends to settle down, while the adjacent trench walls act to hold the soil in place due to shearing stresses along the interfaces. This leads to a load transfer from the fill to the trench walls developing soil arching, hence reducing the vertical pressure transfer to buried box culvert. Another method, ITI, is a construction technique employed to reduce the vertical pressure on buried structure, in which a layer of compressible material is placed directly above the buried culvert to induced positive arching, thus reducing the applied vertical pressure on culvert crown. Meanwhile, some deficiencies have addressed by researchers in each method. Trench Installation in comparison with Induced trench Installation, transfers larger earth load to culvert roof. Also, development of positive arching directly above of culvert roof, transfer more vertical stresses to adjacent soil columns, leading the larger horizontal stresses applied to buried culvert walls. In this study, taking benefits of these two common methods, an installation method has been proposed in which the culvert is installed in a trench with a layer of deformable material placed above the box culvert roof which called Trenched Induced Trench Installation (TITI). Firstly, the transferred pressure to the culvert under the weight of soil and surface pressure, has been validated using numerical analyses and compared with analytical equations which predict the applied pressure. Then, two-dimensional Finite Element Analyses, have been performed to explore the effect of various factors on the applied pressure on roof, side walls and bottom of buried box culvert in TITI method. Results show that soil arching reduces the earth pressure on roof and arching developed between box side walls and trench walls, also can control the pressure applied on the culvert side walls.

کلیدواژه‌ها [English]

  • Induced Trench Installation
  • soil arching
  • buried box culvert
  • Finite Element Analysis