مدلسازی سه‌بُعدی تقاطع تونل‌های مترو خط 6 و 7 تهران به منظور تعیین مناسب‌ترین توالی حفر تونل‌های متقاطع غیرهمسطح

نوع مقاله: مقاله ترویجی

نویسندگان

دانشگاه آزاد اسلامی واحد محلات، گروه معدن، محلات، ایران

چکیده

پارامترهای متعددی مانند توالی حفر، روش حفر، ضخامت پوشش بتنی، فاصله بین دو تونل، طول دهانه پوشش داده نشده، خواص خاک و ... بر میزان اندرکنش تونل‌های متقاطع غیرهمسطح تاثیرگذار هستند. از آنجا که توالی حفر تأثیر زیادی بر نشست سطح زمین و سایر جنبه‌های منفی تونلسازی دارد، لذا یکی از مهمترین پارامترهایی است که باید قبل از حفاری این تونل‌ها علی‌الخصوص در نواحی تقاطع تعیین شود. هدف اصلی این پژوهش تعیین بهترین توالی حفر برای تونل‌های متقاطع غیرهمسطح در نواحی شهری است. بدین منظور تقاطع تونل‌های خطوط 6 و 7 متروی تهران مد نظر قرار گرفته است و بهترین گزینه برای حفاری این تونل‌ها در محل تقاطع آنها به کمک مدلسازی عددی سه‌بُعدی با نرم‌افزار MIDAS GTS NX تعیین شده است. هر دو تونل دارای قطرهای مشابهی بوده و به کمک دستگاه حفر مکانیزه TBM-EPB حفاری می‌شوند. این نرم‌افزار دارای قابلیت‌های خوبی برای مدلسازی تونل‌هایی که با سیستم مکانیزه حفر می‌شوند، است. برای دستیابی به هدف گفته شده، سه سناریو و پنج آلترناتیو در نظر گرفته شد و در هر سناریو اثر توالی حفر بر روی نتایج مدل از قبیل نشست سطح زمین، جابجایی کلی، نیروهای برشی و محوری القا شده در پوشش نهایی تونل‌ها مورد بررسی قرار گرفته است. نتایج نشان می‌دهد بهترین سناریو حالتی است که تونل کم عمق/ بالایی حداقل به میزان 10 برابر قطر زودتر از تونل عمیق/پایینی حفر شود.

کلیدواژه‌ها

موضوعات


عنوان مقاله [English]

3D Modeling of Intersection between line 6 and 7 Tunnels of Tehran Subway to determine the Best Excavation Sequence for Non-Level Crossing Tunnels

نویسندگان [English]

  • Hamid Sherizadeh
  • Saeed Dehghan
چکیده [English]

Summary
There are many factors which affect the interaction between non-level crossing tunnels such as excavation sequence, excavation method, lining thickness, the distance between tunnels, the length of unsupported span, soil properties and etc. The excavation sequence is one of the most important factors which should be determined before construction of their intersections, especially in urban areas as it has many effects on surface subsidence and other negative aspects of tunneling. The main purpose of this study is determining the best excavation sequence for non-level crossing tunnels in urban areas. For this purpose, the intersection between lines 6 and 7 tunnels of Tehran subway has been considered and the best alternative for a sequence of their excavation was determined by 3D numerical models by MIDAS GTS NX, numerical finite element software. Both tunnels have an equal diameter and are excavated by TBM-EPB machines. This software has good capabilities for modeling of mechanized excavation of tunnels. To achieve the above-mentioned objective, three scenarios, and five alternatives were considered and in each scenario, the effect of excavation sequence on the results of the model such as surface subsidence, total displacement, axial and shear forces on lining has been investigated by numerical models. The results show that the best scenario is the excavation of upper/shallow tunnel at least 10 times of diameter earlier than lower/deeper tunnel.
 
Introduction
First of all, assumptions considered are intended. Then, literature was reviewed and the project is introduced precisely. Finally, the 3D model by finite element software was made, and all scenarios and alternatives of excavation sequences were investigated. According to results the best scenario is the excavation of upper/shallow tunnel at least 10 times of diameter earlier than lower/deeper tunnel.
 
Methodology and Approaches
Because there are various factors affecting the interaction of non-level crossing tunnels, so the best method for investigating these, are numerical models. And because the medium that tunnels are constructed in is a continuum, the finite element method for solving the problem is used. And due to 3D nature of the problem, 3D modeling is used.
 
Results and Conclusions
As mentioned before, the best scenario is the excavation of upper/shallow tunnel at least 10 times of diameter earlier than lower/deeper tunnel. Other researchers also believe to the results obtained. So suggestion for feature studies is: the investigation should be focused on only the scenarios that shallower tunnel is excavated first.

کلیدواژه‌ها [English]

  • Excavation Sequence
  • TBM-EPB
  • Numerical modeling
  • Non-Level Crossing tunnels
  • MIDAS GTS NX
[1] Eskandari, Fatemeh. Goshtasbi, Kamran. (2013), Stability analysis of the intersection lines 2,3 & 4 in Mashhad Urban Railway, Master of Science Thesis, Tarbiat modares university, Faculty of Engineering, Department of Mining Engineering (in Persian).
[2] Kim, Sang-Hwan. (1996), Model testing and analysis of interactions between tunnels in clay, PhD dissertation, University of Oxford.
[3] Pound, C. Hsu, Y. S. Walker, G R. (2003), Predicted and Observed Ground Movements around a Tunnel boring machine at Heathrow airport: International Conference on Underground Construction, London, pp. 549-562.
[4] Hefny, A. M., H. C. Chua, and J. Zhao. (2004), Parametric studies on the interaction between existing and new bored tunnels, tunneling and underground space technology, Underground Space for Sustainable Urban Development, proceedings of the 30th ITA-AITES world tunnel congress Singapore, vol. 19, no. 4-5.
[5] Liu, H. Y., J. C. Small, and J. P. Carter. (2008), Full 3D modeling for effects of tunneling on existing support systems in the Sydney region, Tunnelling and Underground Space Technology 23, no. 4, pp.399-420.
[6] J. Yingxuan, L. Weining, S. Xiaojing, L. Weifeng and Z. Hougui, (2008), Dynamic responses of spatial overlapping tunnels induced by passing trains, Underground Facilities for Better Environment and Safety, India, pp. 252-260.
[7] Chen, Guo-xing, LeiChen, and Yan Dai. (2011), The seismic response of intersecting metro tunnels and single tunnel, Proceedings of the 8th International conference on Structural Dynamics. Leuven, Belgium: EURODYN 2011, pp. 459-465.
[8] H. Liu, P. Li and J. Liu, (2011), Numerical investigation of underlying tunnel heave during a new tunnel construction, Tunnelling and Underground Space Technology, pp. 276-283.
[9] Z. Liu, C. Zhou, and F. You, (2012) 3D Numerical Stability Analysis of Overlapped Tunnel Groups under Shield Tunnel Undercrossing, International Journal of Earth Science and Engineering, Vol. 5, No. 5, pp. 1110-1122.
[10] X. G. Li and D. J. Yuan, (2012), Responses of a double-decked metro tunnel to shield driving of twin closely under-crossing tunnels, Tunnels and Underground Space Technology (28), pp. 18-30.
[11] Tohidi. Amin, Sadaghiani. Mohammad Hossein, (2010), An investigation on affecting factors on interaction of constructing non-level crossing tunnels, Master of science Thesis, Sharif university of technology, Faculty of engineering, civil engineering department (in Persian).
[12] Razi. Amir mohammad, Shahriar. Kourosh, (2013), Analysis of interaction of two tunnels (case study: tunnels line 6 and 7 of Tehran subway), Master of science Thesis, Islamic Azad University of Science and Technology, Faculty of Engineering, Mining Engineering Department (in Persian).
[13] Sahel. Consulting Company, Sepasad. engineering company, (2014), Analysis of interaction of tunnels line 6 and 7 of Tehran subway in new corridor (in Persian).
[14] Sherizadeh. Hamid, Dehghan. Saeed, (2016), An improvement of distance between urban tunnels in intersecting areas and an investigation on excavation sequence, Master of science Thesis, Islamic Azad University of Mahallat, Faculty of Engineering, Mining Engineering Department (in Persian).