تخمین تنش‌های اصلی القایی در کارگاه‌های جبهه‌کار طولانی از طریق وارونه‌سازی تانسور گشتاور لرزه‌ای

نوع مقاله: مقاله پژوهشی

نویسندگان

1 گروه مهندسی معدن، دانشگاه صنعتی همدان

2 دانشکده مهندسی معدن و متالورژی، دانشگاه صنعتی امیرکبیر

3 دانشکده مهندسی معدن، دانشگاه کرتین استرالیا

چکیده

با استخراج لایه زغالسنگ در کارگاه‌های جبهه­کار طولانی، شرایط تعادل تنش­های برجا تغییر کرده و توزیع مجدد تنش‌های برجا در محدوده کارگاه استخراج منجر به افزایش تمرکز تنش در پیرامون پهنه می­شود. توزیع مجدد میدان تنش در اطراف کارگاه استخراج سبب ایجاد تنش‌های القایی و به تبع آن تغییرشکل و جابه‌جایی توده‌سنگ می‌شود. در این خصوص به علت تمرکز تنش در اطراف کارگاه استخراج، فشار تکیه­گاهی جلویی از اهمیت بیش‌تری برخوردار است. از این رو در این پژوهش سعی شده است جهت تنش‌های اصلی القایی پیرامون کارگاه استخراج با استفاده از داده‌های لرزه‌نگاری و از طریق وارونه‌سازی تانسور گشتاور لرزه‌ای تعیین شود. به این ترتیب با تجزیه و تحلیل امواج لرزه‌ای القایی که در اثر تمرکز تنش منتشر می‌شوند، تانسور گشتاور لرزه‌ای محاسبه شده و سپس با استفاده از مقادیر ویژه و بردارهای ویژه، جهت تنش‌های القایی تخمین زده می‌شوند. برای این منظور با انتخاب کارگاه E2 معدن زغالسنگ طبس به عنوان مطالعه موردی، امواج لرزه‌ای متناظر با 24 ریزش سقف در این کارگاه مورد تجزیه و تحلیل قرار گرفته است. نتایج حاصل از این پژوهش نشان می‌دهد که مکانیزم شکست غالب در این کارگاه به صورت فشاری/کششی ظاهر شده است. همچنین ناپایداری‌های کارگاه عمدتاً ناشی از تمرکز تنش بوده و موقعیت فضایی آنها در محدوده جبهه‌کار متمرکز شده است. از طرف دیگر شکست برشی بیشتر در محدوده گسل‌های منطقه ظاهر شده است. به طور کلی در بیش‌تر موارد جهت بیشینه تنش اصلی القایی نسبت به افق زاویه حاده داشته است. این موضوع نشان می‌دهد که تنش‌های القایی افقی بیش‌ترین تأثیر را در ناپایداری و وقوع شکست سقف داشته‌اند.

کلیدواژه‌ها

موضوعات


عنوان مقاله [English]

Estimation of Principal Induced Stresses in Longwall Faces through Seismic Moment Tensor Inversion

نویسندگان [English]

  • Satar Mahdevari 1
  • Kourosh Shahriar 2
  • Mostafa Sharifzadeh 3
1 Dept. of Mining, Hamedan University of Technology, Iran
2 Dept. of Mining and Metallurgy, Amirkabir University of Technology, Iran
3 Dept. of Mining, Curtin University, Australia
چکیده [English]

Summary
In parts of constructing east-west section of line7 Tehran subway, the excavating machine (EPB-TBM) passes from the top of the Abouzar’s wastewater conveyance tunnel with clear distance of 2.25 m. The FLAC 3D has been used to model this problem and find the deformations and forces of ground and linings. The modeling results showed that after excavating subway tunnel, lining of Abouzar tunnel will move upward due to the increasing plastic zones and stress relaxation. This rate of displacement induced the internal force more than allowable designed amount in concrete lining of Abouzar tunnel.
 
Introduction
Generally, excavating a tunnel near another tunnel may lead to significant interaction effects, which mainly depends on tunnels position relative to each other (parallel or cross), the distance between two tunnels, tunnel dimensions, lining rigidity, stress and boring environment condition as well as the method of tunnel boring. The interaction between adjacent tunnels have been investigated by different researchers using methods such as analytical and empirical, field observation, physical modeling and numerical modeling. In the current project, the tunnel of Tehran metro line7 passes with a distance of 2.25 meters from the top of the Abouzar tunnel. Because of the three-dimensional nature of the interaction problem between underground spaces, numerical modeling is an appropriate tool for the analysis of these complicated problems. Therefore, FLAC3D software has been used in order to investigate the interaction analysis. The purpose of modeling is to study stability of support system of Abouzar tunnel during tunnel excavation of Tehran metro line7.
 
Methodology and Approaches
In this paper, the finite difference method (FDM) is used for modeling and solving the problem. FLAC 3D program which uses FDM was selected in order to study the interaction between the two tunnels, in construction stage. For this purpose, at first Abouzar tunnel modeled and excavated, then impact of stepwise excavating of line7 Tehran subway on lining system of Abouzar tunnel is investigated numerically. History of Internal forces, bending moments and structural displacement of Abouzar’s tunnel lining have been provided and studied. Engineering recommendations have been proposed in different-leveled intersecting tunnels.
 
Results and Conclusions
The results of the modeling showed that after excavation of metro tunnel, the support system of Abouzar tunnel will be uplifted because of increasing plastic zone and stress relaxation. This displacement causes internal forces in Abouzar tunnel lining which are more than allowed values.

کلیدواژه‌ها [English]

  • Longwall Mining Method: Principal Induced Stresses
  • Seismic Moment Tensor
  • Mining Induced Seismicity
  • Tabas Coal Mine
[1]           Peng, S.S. (2008). Coal Mine Ground Control. 3rd Edition, West Virginia University, Department of Mining Engineering, College of Engineering and Mineral Resources, Morgantown, p.750.

[2]           Gibowicz, S.J. and Lasocki, S. (2001). Seismicity induced by mining: ten years later, In: Dmowska R, Saltzman B. (Eds.), Adv Geophys 44:39–181. ISBN: 0-12-018844-9.

[3]           Peng, S.S. (2006). Longwall mining, 2nd edn. Morgantown, West Virginia, ISBN: 0-9789383-0-5.

[4]           Whittaker, B.N. (1974). An appraisal of strata control practice. Min Eng 134(166):9-29.

[5]           Bieniawski, Z.T. (1987). Strata control in mineral engineering. John Wiley & Sons, ISBN: 9780470203293.

[6]           Kripakov, N.P. (1982). Alternatives for controlling cutter roof in coal mines. In Proc. of 2nd Int. Conf. on Ground Control in Mining (West Virginia University, Morgantown): 142-151.

[7]           Hill, J.L. and Bauer, E.R. (1984). An investigation of the causes of cutter roof failure in a central Pennsylvania coal mine: a case study. In Proc. of 25th US Symp. on Rock Mechanics (AIME, New York): 603-614.

[8]           Whittaker, B.N. (1982). A review of progress with longwall mine design and layout. In: Proc. of State-of-the-Art of Ground Control in Longwall Mining and Mining Subsidence (AIME, New York): 77-84.

[9]           Everling, G. and Jacobi, O. (1977). Longwall mining in Germany: rock pressure and design of mine layouts. In: Proc. of 6th Int. Strata Control Conf. (Banff): paper I-2.

[10]         Guo, H. Yuan, L. Shen, B. Qu, Q. Xue, J. (2012). Mining-induced strata stress changes, fractures and gas flow dynamics in multi-seam longwall mining. Int J Rock Mech Min Sci 54:129–139. doi: 10.1016/j.ijrmms.2012.05.023.

[11]         Rezaei, M. Hossaini, M.F. Majdi, A. (2015). Determination of Longwall Mining-Induced Stress Using the Strain Energy Method. Rock Mech Rock Eng 48(6). doi: 10.1007/s00603-014-0704-8

[12]         Zhang, N. Zhang, N. Han, C. Qian, D. Xue, F. (2014). Borehole stress monitoring analysis on advanced abutment pressure induced by Longwall Mining. Arab J Geosci 7:457-463. doi:10.1007/s12517-013-0831-7

[13]         Mendecki, A.J. (2016). Mine seismology reference book: seismic hazard. Institute of Mine Seismology. ISBN: 978-0-9942943-0-2.

[14]         Driad–Lebeau, L. Lahaie, F. Al Heib, M.A. Josien, J.P. Bigarre´, P. Noirel, J.F. (2005). Seismic and geotechnical investigations following a rockburst in a complex French mining district. Int J Coal Geol 64:66–78.

[15]         Al Heib, M. (2012). Numerical and geophysical tools applied for the prediction of mine induced seismicity in French coalmines. Int J Geosci 3:834-846. doi: 10.4236/ijg.2012.324084.

[16]         Boltz, M.S. Pankow, K.L. McCarter, M.K. (2014). Fine details of mining-induced seismicity at the Trail Mountain coal mine using modified hypocentral relocation techniques. Bull Seismol Soc Am 104(1):193–203. doi: 10.1785/0120130011.

[17]         Calleja, J. Nemcik, J. (2016). Coalburst causes and mechanisms. In: Aziz N, Kininmonth B. (eds.), Proc 16th Coal Operators’ Conference, Mining Engineering, University of Wollongong, 10-12 February 2016, pp. 310-320.

[18]         Czarny, R. Marcak, H. Nakata, N. Pilecki, Z. Isakow, Z. (2016). Monitoring velocity changes caused by underground coal mining using seismic noise. Pure Appl Geophys 173(6):1907-1916. doi: 10.1007/s00024-015-1234-3.

[19]         Kozłowska, M. Orlecka-Sikora, B. Rudziński, Ł. Cielesta, S. Mutke, G. (2016). Atypical evolution of seismicity patterns resulting from the coupled natural, human-induced and coseismic stresses in a longwall coal mining environment. Int J Rock Mech Min Sci 86:5-15. doi: 10.1016/j.ijrmms.2016.03.024.

[20]         Rudziński, Ł. Cesca, S. Lizurek, G. (2016). Complex rupture process of the 19 March 2013, Rudna Mine (Poland) induced seismic event and collapse in the light of local and regional moment tensor inversion. Seismol Res Lett 87(2A). doi: 10.1785/0220150150.

[21]         Gilbert, F. (1971). Excitation of the normal modes of the earth by earthquake sources. Geophys J Roy Astron Soc 22(2):223–226. doi: 10.1111/j.1365-246X.1971.tb03593.x.

[22]         Udiás, A. (1999). Principles of seismology. Cambridge University Press, Cambridge. ISBN: 0-521-62478-9.

[23]         Aki, K. and Richards, P.G. (2002). Quantitative seismology. 2nd edn. University Science Books, Sausalito, CA. ISBN: 978-1891389634.

[24]         Jost, M.L. and Herrmann, R.B. (1989). A student’s guide to and review of moment tensors. Seismol Res Lett 60:37-57. doi: 10.1785/gssrl.60.2.37.

[25]         Gibowicz, S.J. and Kijko, A. (1994). An introduction to mining seismology. Academic Press Inc. ISBN: 0-12-282120-3.

[26]         Shearer, P.M. (2009). Introduction to Seismology. 2nd edn. Cambridge University Press. ISBN: 9780521708425.

[27]         Lowrie, W. (2007). Fundamentals of geophysics. 2nd edn. Cambridge University Press. ISBN: 978-0-511-35447-2.

[28]         Google earth, V 7.1.5.1557. (2009). Parvadeh Coal mines, Tabas. 33_00036.3700N, 56_49030.1500E, elev 2746 ft. Digital Globe 2015. [http://www.earth.google.com]

[29]         IRITEC. (2003). Tabas Coal Mine Project, detailed design report, vol 1, underground mine revision B. Iran International Engineering Company (IRITEC), p 464.

[30]         Michael, A.J. (1987). Use of focal mechanisms to determine stress: a control study. J Geophys Res 92(B1):357-368. doi: 10.1029/JB092iB01p00357.

[31]         Reid, H.F. (1911). The elastic-rebound theory of earthquakes. Bulletin of the Department of Geology, University of California Publications: 6(19):413-444.

[32]         Cook, N.G.W. (1976). Seismicity associated with mining. Eng Geol 10(2-4):99-122. doi: 10.1016/0013-7952(76)90015-6.