بررسی خصوصیات زمین‌شناسی مهندسی توده‌سنگ‌های میزبان تونل قطعه سوم آزاد‌راه ارومیه - تبریز و پیشنهاد سیستم نگهدارنده بر اساس روش‌های تجربی و عددی

نوع مقاله : مقاله پژوهشی

نویسندگان

1 گروه زمین‌شناسی کاربردی، دانشکده علوم زمین، دانشگاه خوارزمی، تهران، ایران

2 گروه راه و راه‌آهن، شرکت طرح نو اندیشان، تهران، ایران

چکیده

یکی از مهم­ترین مباحث در علم مکانیک سنگ و همچنین زمین­شناسی مهندسی، تحلیل پایداری فضاهای زیرزمینی قبل از انجام حفاری است. بحث این مقاله پیرامون خصوصیات زمین­شناسی مهندسی توده­سنگ، تحلیل پایداری و پیشنهاد سیستم نگهدارنده برای تونل قطعه سوم آزادراه ارومیه- تبریز است. محل حفاری این تونل درون سنگ­های آذرین جزیره اسلامی است که با توجه به مسائل مهندسی مختلف به پنج واحد ژئوتکنیکی متفاوت تقسیم شد. از روش­های رایج تحلیل پایداری فضاهای زیرزمینی استفاده از روش­های تجربی و عددی است. در این مقاله برای تحلیل پایداری تونل قطعه سوم آزادراه ارومیه- تبریز از روش­های تجربی طبقه­بندی RMR، Q، GSI و RMi و روش عددی اجزاء محدود استفاده شد. در تحلیل به روش عددی از نرم افزار PLAXIS و برای تشخیص گوه­های بحرانی از نرم افزار Unwedge بهره برده شد. نتایج تحلیل­ها نشان داد که در حفاری تک مرحله­ای جابه­جایی توده­سنگ بیش از حد مجاز به دست آمده از روش ساکورایی است، بنابراین پیشنهاد شد حفاری به صورت دو مرحله­ای انجام شود. در ادامه سیستم نگهداری موقتی که ضریب اطمینان مورد نیاز را تأمین کند، با استفاده از روش­های تجربی و عددی پیشنهاد گردید. همچنین به منظور اعتبارسنجی و تأیید صحت روند مدل­سازی در نرم افزار PLAXIS، از نرم افزار Phase2 استفاده شد.

کلیدواژه‌ها

موضوعات


عنوان مقاله [English]

Investigation of the engineering geological properties of host rock masses in section third of Urmia - Tabriz freeway tunnel and suggested support system based on empirical and numerical methods

نویسندگان [English]

  • Hessam Jamalizadeh 1
  • Mahmoud Fatemi Aghda 1
  • Mehdi Talkhablou 1
  • Ehsan Mokhtari 2
1 Department of Applied Geology, Faculty of Earth Sciences, Kharazmi University, Tehran, Iran
2 Road and Railway Group, Tarhe No Andishan Company, Tehran, Iran
چکیده [English]

Introduction


The issue of stability and maintenance of the rock mass structure is one of the inevitable cases for the construction of underground structures. The third section of the Urmia-Tabriz Freeway Project will approximately reduce the length of the path 12 km by running the two tunnels system with an approximate length of 4.4 km.


Materials and methods


Based on field studies, two units of Trachytic (OMtr) and Gabbroic (OMgb) with Oligo-Miocene age were identified as host rocks. These two units are subdivided into smaller units called OMtr (1), OMgb (2), OMgb (2), OMtr(2) and Cr due to various engineering issues such as differences in engineering geological properties, overhead height and etc.


Investigation of engineering geology and geotechnic of host rock masses usually include discontinuity identification, exploratory drilling, and rock mass engineering classification. In addition, numerical analysis is performed using PLAXIS.


Results and discussion


Generally, 170 discontinuities were surveyed and analyzed using Dips 5.1. There are three main joints along the tunnel, critical wedges were detected with the help of Unwedge which suggested 1cm thick reinforced shotcrete for their stability.


The rock masses were classified, according to the empirical methods RMR, Q, GSI and RMi based on the support system proposed. Allowable displacement in the tunnel was also determined using empirical equations (Sakurai equations). The minimum allowable displacement is 1.94 cm for unit OMgb (1) and the highest at 3.13 cm is for unit Cr.


PLAXIS which is a finite element program, was used for numerical analysis. In one-step drilling, excessive allowable displacement is obtained by empirical equations and then modeled through two-stage drilling. The results determined the thickness of the shotcrete with a compressive strength of 250 kg/cm2 in OMtr (1) unit, 5 cm, in OMgb (2), OMgb (1) and OMtr (2) units, 10 cm and in the Cr unit it was modeled 15 cm. Also, the safety factor of different units shows that the lowest is OMtr (1), which is higher than the minimum required safety factor.


Phase2 was used to validate the modeling. To avoid duplication, two units of OMtr (1) and Cr were validated. The maximum displacement in unit OMtr (1) is 0.24 cm and in unit Cr it is 1.41 cm.


Conclusion


According to empirical classifications, rock mass quality is determined as good for OMgb (1) unit, fair for OMgb (2), OMtr (1) and OMtr (2) units and as poor for Cr unit. Due to the quality of the rock mass, the support system of 3 m long rock bolt, spaced at 1.35 to 2.5 m and 5 to 6 cm of reinforced shotcrete for OMgb (1) unit, 4 m long rock bolt, spaced at 1 to 2 m and 10 to 15 cm of reinforced shotcrete for OMgb (2), OMtr (1) and OMtr (2) units with 4 to 5 m long rock bolt, spaced at 1 to 2 m were suggested.  More than15 cm of reinforced shotcrete was suggested for Cr unit.


According to the support system in PLAXIS, shotcrete with thicknesses of 5, 10 and 15 cm was suggested for OMtr (1) - OMgb (1), OMgb (2). OMtr (2) - Cr.


It was observed that the maximum displacement in all units was less than the calculated value by the Sakurai method and the least safety factor is also 2.13 for OMtr (1) unit. The model was validated with Phase2 and the results were very close.


 

کلیدواژه‌ها [English]

  • Stability analysis
  • Part third tunnel of Urmia-Tabriz freeway
  • Engineering geological properties
  • Support system
  • Empirical classification
  • PLAXIS and Unwedge software
اجل لوئیان، ر.، دادخواه، ر. و حسین میرزایی، ز.، 1395. کاربرد زمین­شناسی مهندسی در تونل­ها، چاپ اول، انتشارات علوی، تهران. 333 ص.
-آقانباتی، ع.، 1385. زمین­شناسی ایران، چاپ دوم، انتشارات سازمان زمین‌شناسی و اکتشاف معدنی کشور، تهران. 640 ص.
-سلطانی سیسی، غ.، امینی آذر، ر.، یوسفی راد، ا. و جلال­زاده، م.، 1384. نقشه زمین‌شناسی 1:100000 ارومیه، انتشارات سازمان زمین‌شناسی کشور، تهران.
-شرکت مهندسی طرح نو اندیشان، 1396. گزارش زمین‌شناسی مهندسی و ژئوتکنیک مسیر قطعه 3 آزادراه ارومیه – تبریز، تهران، 158 ص.
-طریق ازلی، ص.، 1383. تحلیل پایداری تونل انحراف سد درونگر و ارائه سیستم نگهدارنده، پایان‌نامه کارشناسی ارشد، دانشگاه فردوسی مشهد.
-قدیرزاده، ا. و انوری، ا.، 1381. نقشه زمین‌شناسی 1:100000 آذرشهر، انتشارات سازمان زمین‌شناسی کشور، تهران.
-نبوی، م.ح.، 1355. دیباچه‌ای بر زمین­شناسی ایران، انتشارات سازمان زمین‌شناسی کشور، تهران،  109 ص.
-نقشه 1:2500000 راه‌ها، 1392. سازمان نقشه‌برداری کشور.
 
 
 
-Barton, N., Loset-Lien, R. and Lunde, J., 1980. Application of the Q-system in design decisions: In Subsurface spsce, v. 2, p. 553-561.
-Bieniawski, Z.T., 1989. Engineering Rock Mass classification: Wiley, New York, 251 p.
-Bieniawski, Z.T., 1973. Engineering classification of jointed rock masses: Trans S. Afr. Inst. Civ. Engrs, v. 15, p. 335-344.
-Brown, E.T. and Hoek, E., 1978. Trends in relationships between measured rock in situ stresses and depth. Int. J. Rock Mech. Min. Sci. & Geomech. Abstr., v. 15, p. 211-215.
-Cai, M., Kaiser, P.K., Uno, H., Tasaka, Y. and Minami, M., 2004. Estimation of rock mass deformation modulus and strength of jointed hard rock masses using the GSI system: Int. J. Rock Mech. Min. Sci., v. 41, p. 3-19.
-Carranza Torres, C. and Diederichs, M., 2009. Mechanical analysis of circular Liners with particular refrence to composite supports. For example, liners consisting of shotcrete and steel sets. Tunneling and underground space technology, v. 24, p. 506-532.
-Grimstad, E. and Barton, N., 1993. Updating the Q-System for NMT: Proc. Int. Symp. On Sprayed Concrete Modern use of Wet Mix Sprayed Concrete for Underground Support, Fagernes, (eds Kompen, Opsahl and Berg). Oslo: Norwegian Concrete Assn, v. 9, p. 119-127.
-Hoek, E. and Brown, E.T., 1988. The Hoek-Brown failure criterion – update: Proc. 15th Canadian Rock Mech. Symp. (ed. J.H. Toronto: Civil Engineering Dept., University of Toronto), p. 167-179.
-Hoek, E., Kaiser, P.K. and Bawden, W. F., 1998. Support of underground excavation in hard rock: A. A. Balkema, Rotterdam, 275 p.
-Hoek, E., Marinos, P. and Benissi, M., 1998. Applicability of the geological strength index (GSI) classification for very weak and sheared rock masses The case of the Athens Schist Formation: Bulletin Engineering Geology and the environment, v. 57, p. 151-160.
-Hsiao, F.Y., Wang, C.L. and Chern, J.C., 2009. Numerical simulation of rock deformation for support design: Tunnelling and Underground Space Technology, v. 24, p. 14-21.
-ISRM, 1981. Suggested Methods for the Quantitative Description of Discontinuities in Rock Masses: Rock Characterization, Testing and Monitoring, London. Pergamon, Oxford, 221 p.
-McCutchin, W.R., 1982. Some Elements of a Theory of Insitu Stresses, hit. Jr. Rock Mech. and Min. Sci. & Geomech. Abstr., Pergamon, v. 19, p. 201-203.
-Palmstrom, A., 1996. Characterizing rock mass by the RMi for use in practical rock engineering, Part 2: some practical application of the Rock Mass index: Tunneling and underground space technology, v. 11, p. 287-303.
-Palmström, A., 2000. Recent developments in rock support estimates by the Rmi:  Journal of Rock Mechanics and Tunnelling Technology, v. 6, p. 1-19.
-Purwanto, P., 2013. Fundamental study on support systemat cibaliung underground gold mine, Indonesia, procedia earth and planetary science, v. 6, p. 419-425.
-Rahimi, B., Shahriar, K. and Sharifzadeh, M., 2014. Evaluation of rock mass engineering geological properties using statistical analysis and selecting proper tunnel design approach in Qazvin–Rasht railway tunnel", Tunnelling and Underground Space Technology, v. 41, p. 206-222.
-Rehman, H., Naji, A.M., Ali, W., Junid, M., Abdullah, R.A. and Yoo, H., 2020. Numerical evaluation of new Austrian tunneling method excavation sequences: A case study. International Journal of Mining Science and Technology, v. 30, p. 381-386.
-Sakurai, S., 1997. Lessons learned from field measurements in tunneling: Tunneling and underground space technology, v. 12, p. 453- 460.
-Sakurai, S., Akutagawa, S., Takeuchi, K., Shinji, M. and Shimizu, N., 2008. Back analysis for tunnel engineering as a modern observational method: Tunneling and Underground Space Technology, v. 62, p. 185-196.
-Sheory, P.R., 1994. A theory for in Situ Stresses in Isotropic and Transversely Isotropic Rock. International Journal of Rock Mechanics and Mining Sciences & Geomechanics Abstracts, v. 31, p. 23 -34.
-Singh, B. and Goel, R.K., 1999. Rock Mass Classification: A Practical Approach in Civil Engineering: Elsevier Science, 282 p.
-Terzaghi, K. and Richart, F.E., 1952. Stresses in rock about cavities. Geotechnique, v. 3, p. 57-90.
-Varadarajan, A., Sharma, K.G., Desai, C.S. and Hashemi, M., 2001. Analysis of a powerhouse cavern in the Himalaya: Int. J. Geomech, v. 1, p. 109-127.
-Yasitli, N.E., 2016. Comparison of input parameters regarding rock mass in analytical solution andnumerical modelling. Journal of African Earth Sciences.Soutthern Africa, v. 45, p. 188-216.
-Yertutanol, K., Akgün, H. and Sopacı, E., 2020. Displacement monitoring, displacement verification and stability assessment of the critical sections of the Konak tunnel, İzmir, Turkey. Tunnelling and Underground Space Technology, v. 101.