ارائه معیاری جهت تعیین کمترین فاصله بین تونل‌های موازی توسط منحنی واکنش پایه (PRC)

نوع مقاله: مقاله پژوهشی

نویسندگان

1 گروه زمین شناسی، دانشگاه اصفهان

2 استاد گروه زمین شناسی مهندسی، دانشکده علوم پایه، دانشگاه اصفهان، ایران

چکیده

تعیین فاصله‌ی حفاری بهینه بین تونل‌های موازی از اهمیت فراوانی برخوردار است. مدل‌های تجربی فراوانی جهت تخمین عرض پایه تونل وجود دارد که هر یک محدودیت‌هایی دارند. در این مقاله، معیاری جهت طراحی عرض پایه بین تونل‌های موازی (دوقلو) ارائه شده است. این معیار مبتنی بر منحنی واکنش زمین و با استفاده از مدل‌سازی عددی در شرایط مختلف است. مقدار کرنش در لحظه رسیدن میزان تنش عمودی (1σ) در پایه به مقدار مقاومت فشاری توده سنگ (cmσ) نشانگر نسبت قابل قبول عرض به ارتفاع (w/h) می‌باشد که بیانگر فاصله بهینه بین تونل‌های دوقلو است. بدین منظور تونل دوقلوی پونه که در آزاد راه اراک- خرم‌آباد قرار دارد به عنوان مطالعه موردی انتخاب شده است. این تونل از هشت زون در لایه‌های سنگ آهک مارنی و یک زون در نهشته‌های آبرفتی می‌گذرد. نتایج حاکی از آن است که روش پیشنهادی تطابق خوبی بین ابعاد پایه در مشاهدات تونل مورد مطالعه با در نظر گرفتن ابزار دقیق نصب شده در تونل دارد. برای نمونه در زون 3 مقدار مقاومت فشاری توده سنگ 23/3 مگاپاسکال و مقدار کرنش در محدوده پایه 053/0 است. بر اساس تحلیل‌ها در این زون مقدار 8/1w/h= به دست آمده که عرض پایه پایدار حداقل 1/17 متر محاسبه گردید. درنتیجه با در نظر گرفتن این معیار می‌توان بهینه‌ترین عرض پایه را در طراحی تونل‌های دوقلو در حالت استاتیک با دقت مناسبی در تونل‌های ایران بدست آورد.

کلیدواژه‌ها


عنوان مقاله [English]

A criterion for determination of minimum distance between twin tunnels by pillar reaction curve (PRC)

نویسندگان [English]

  • Hossein Ghorbani 1
  • Rassoul Ajalloeianb 2
1 Department of Geology, University of Isfahan
2 Department of Geology, University of Isfahan, Isfahan, Iran
چکیده [English]

Determination of optimum distance between twin tunnels is very important. There are many empirical models to estimate width of the pillar, all of which have their own limitations. In this study an attempt was made to present a new criterion for design of the pillar between twin (parallel) tunnels. It is based on ground reaction curve and numerical modelling. Strain magnitude observed when normal stress (σ1) in the pillar reaches the value of compressive strength of the rock mass (σcm), denotes the allowable ratio of width to height (w/h) which shows the optimum distance between twin tunnels. Pooneh twin tunnels located in Arak-Khoramabad Expressway, was selected as a case study. This Tunnel is made of eight zones in layers of marly limestone and one zone in alluvial deposits. Results of the suggested method show a good agreement between the pillar dimensions seen in the case study obtained from instrumentation and the method (new criterion). In zone 3, as an example, the amounts of rock mass compressive strength and strain in the pillar are 3.23 MPa and 0.053, respectively. In this zone, 1.8 was obtained for the w/h ratio, according to the analysis the minimum width for the stable pillar must be 17.1 m. Taking all aspects of geomechanical and geometrical characteristics of the tunnels into consideration, this method is capable of determining the optimum width of the pillar when designing the twin tunnels in static conditions with a high level of precision in all Iranian tunnels.

کلیدواژه‌ها [English]

  • twin tunnels
  • Pillar reaction curve
  • Pooneh tunnel
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