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
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