بازنگری کارایی شاخص کیفی سنگ (RQD) در سیستم رده‌بندی ژئومکانیکی توده‌سنگ (مطالعه موردی تونل البرز)

نوع مقاله: مقاله پژوهشی

نویسندگان

1 دانشجوی کارشناسی ارشد؛ دانشکده مهندسی معدن، پردیس دانشکده‌های فنی دانشگاه تهران،

2 دانشکده مهندسی معدن، پردیس دانشکده‌های فنی دانشگاه تهران،

3 دانشجوی دکتری؛ موسسه فناوری سلطنتی KTH، استکهلم، سوئد

10.22044/tuse.2020.9245.1384

چکیده

سیستم‌های رده‌بندی توده‌سنگ به عنوان بخش اصلی روش‌های تجربی طراحی نقشی کلیدی در صنعت تونلسازی بازی می‌کنند. سیستم رده‌بندی ژئومکانیکی توده‌سنگ (RMR) به عنوان یکی از رایج‌ترین سیستم‌ها در سال 1973 توسط بنیاوسکی ارایه و پس از بکارگیری در شرایط مختلف، توسط محققین توسعه داده شد. به دلیل حساسیت بالا در توصیف درست از رفتار توده‌سنگ، نیاز به بررسی دقیق‌تر پارامترهای ورودی این سیستم-ها احساس می‌شود. در سال‌های اخیر بررسی کارایی RQD یکی از موضوعات مهم مورد بحث است. به دلیل نواقص عنوان‌شده برای RQD و همچنین هم‌پوشانی آن با پارامتر فاصله‌داری شکستگی‌ها (FS)، استفاده از پارامتر تناوب شکستگی (FF) به عنوان جایگزین مطرح شده است. بر اساس این پارامتر در سال 2013 نسخه جدیدی از RMR تحت عنوان RMR13 ارایه ‌شد. در این مقاله به بررسی کارایی پارامتر FF‌ و مقایسه نتایج استفاده از آن در RMR13 با نتایج RMR89، بر اساس بخشی از داده‌های تونل البرز در آزادراه تهران- شمال پرداخته شده است. اختلاف نتایج بدست آمده برای دو روش حدود 2 درصد است، که با توجه به ماهیت تجربی RMR، نشانگر نتایج قابل قبول برای روش RMR13 است. بنابراین با توجه به ایرادات مطرح‌شده برای RQD، استفاده از RMR13 در پروژه‌های جدید پیشنهاد می‌شود، که برخلاف پروژه‌های قدیمی تاریخچه مطالعات آن‌ها بر اساس RQD نیست.

کلیدواژه‌ها


عنوان مقاله [English]

Revision of using Rock Quality Designation (RQD) in Rock Mass Rating System (RMR) – a Case Study of Alborz Tunnel

نویسندگان [English]

  • H. Farajollahi 1
  • M. H. Khosravi 2
  • M. Mohammadi 3
1 School of Mining Engineering, College of Engineering, University of Tehran
2 School of Mining Engineering, College of Engineering, University of Tehran
3 KTH Royal Institute of Technology, Stockholm, Sweden
چکیده [English]

Empirical and numerical methods are commonly used when underground engineering structures are designed. Empirical methods are generally preferred by rock engineers and geologists due to their practicality. In designing tunnel supports, rock mass classification systems, RMR, Q, and RMi have been used by many researchers and gained universal acceptance. These classification systems have been originally obtained from many tunneling case studies and they have been applied to many construction designs. It is necessary to select the appropriate parameters as inputs to these systems in order to accurately describe the rock behavior. Therefore, researchers tend to look more closely at the input parameters. RQD and FS, two input parameters to RMR, and recently introduced parameter FF as their alternative, has been discussed in this paper. Also, the applicability of FF has been investigated on Alborz tunnel data as a case study. Traditionally, parameter ratings were determined from the presented tables for RMR. However, some users were not aware that the ratings in these tables were the average values for the ranges shown and not the minimum values. For improved accuracy, it is better to use the recommended graphs, showing the continuous value of the ratings. Therefore, the presented graph was used to determine the value of FF parameter as a combined rating of RQD and FS. RMR13 has obtained by replacing FF rating instead of the total rating for RQD and FS in RMR89. The values obtained for FF rating were highly correlated with the total rating for RQD and FS. Also, the total rate of RMR13 was similar to RMR89 with a correlation coefficient of 0.996, the values obtained for RMR13 was approximately 2 percent higher than these for RMR89. In general, using both versions of RMR are practical and acceptable, but the choice of each to use, depends on the project conditions and system user capabilities.

کلیدواژه‌ها [English]

  • Rock Mass Rating (RMR)
  • Rock Quality Designation (RQD)
  • Fracture Spacing (FS) Fracture Frequency (FF)
  • Alborz Tunnel
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