Simulation of the roughness of rock mass discontinuity using the DRS method

Document Type : Research Article

Authors

1 Mining PhD Student, Faculty of Mining Engineering, Petroleum and Geophysics, Shahrood University of Technology

2 Associate Professor, Faculty of Mining Engineering, Petroleum and Geophysics, Shahrood University of Technology

3 Assistant Professor, Faculty of Mathematical Sciences, shahrood university and technology

Abstract

Summary
One of the important geometric features of rock mass discontinuities is its surface roughness. The discontinuity level has different heights that differentiate each level from the other. In practice, it is not possible to assign a roughness value to each of these levels, so to levels that are similar in height; The same amount of roughness is assigned. In analyzing the problems of stone mechanics related to coercion, it is necessary to choose one of the many levels of discontinuities that have the same amount of roughness. Discontinuity Roughness Simulation (DRS) is a random selection of different levels of surface roughness for a certain amount of surface roughness. In this method, the level of discontinuity is simplified by connecting several pieces together; So that each piece has an unevenness. By simplifying and using different layouts of components that make up the discontinuity surface, the DRS method can produce different levels, the JRC value of which is almost the same.
 
Introduction
Several methods have been proposed to measure the roughness feature of rock mass, all of them work based on the elevation of its fracture's measurement. Precise measurements and illustration of roughness values were the subjects of the previous studies.
 
Methodology and Approaches
Barton's field method and determination of the maximum distance, a, between fracture and the field survey profile, L, is the foundation of the proposed method here. So fracture's length would be divided into n pieces in which its length is less than L and there exist an asperity with the height of a. By considering a number between 0 and an as the flange's height and a random number in the [0,l] interval as the distance between two adjacent flanges, locus of the fracture's flange points would be determined. The locus of the fracture's atrio points would be determined by measuring the distance between two adjacent flange and atrio points of a fracture which is a number between 0 and two adjacent flanges.
 
Results and Conclusions
In order to validate and ensure the accuracy of the results obtained from the application of the DRS method, the validity, and reliability of the method have been checked for all possible JRCs. The results of the validity test for different JRCs indicated that the value of the mean percentage of absolute error (MAPE) for different parts of a simulated fracture is always less than 10 percent and this means that if a fracture needs to be simulated using the DRS method in order to produce a roughness value of JRC = 10, the JRC value for all parts of the simulated fractures would a number be between 9 and 11. The reliability of the DRS method for different JRCs has also been investigated. Outcomes showed that the value of MAPE in 100 of repetition of DRS method implementation for a part of the simulated fracture that is randomly determined is less than 6 percent, which is an acceptable value and a confirmation of the accuracy of the DRS method to simulate and produce fracture’s roughness. 

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Full Text

ناپیوستگی‌های توده‌سنگ دارای ویژگی‌هایی همچون جهت‌داری، فاصله‌داری، پایایی، بازشدگی و زبری است. به‌جز مقادیر پایایی و زبری در فضای سه‌بعدی، مقدار عددی دیگر ویژگی‌ها با اندازه‌گیری مستقیم قابل‌بیان هستند و اختلاف بین مقدار واقعی و اندازه‌گیری شده بستگی به خطاهای اندازه‌گیری دارد. مقدار عددی زبری که نشان‌دهنده‌ی پستی‌وبلندی‌های سطح ناپیوستگی است با روش‌های غیرمستقیم تعیین می‌شود. تحقیقات زیادی توسط عده‌ای از پژوهشگران همچون بارتون و چوبی [1]، دویلی و همکاران [2]، گراسلی و همکاران [3] و هردا [4] در مورد برداشت زبری در حالت‌های دوبعدی و سه‌بعدی و در مقیاس آزمایشگاهی و صحرایی انجام‌شده است. هم‌چنین توسط پژوهشگران سایر زمینه‌های مهندسی مختلف روش‌هایی برای بیان زبری ارایه شده است. در مهندسی سنگ، روش ضریب زبری ناپیوستگی (JRC[i]) بارتون متداول‌تر است، به‌طوری‌که پژوهشگران زیادی همچون تسه و کوردن [5]، یو و وایساده [6]، تاتون و گراسلی [7]، جانگ و همکاران [8] به ارایه‌ رابطه بین JRC و دیگر روش‌های بیان زبری پرداخته‌اند. در این مقاله منظور از بیان مقدار زبری مقدار JRC آن است. موضوع تحقیق این مقاله با پژوهش‌های گذشته تفاوت اساسی دارد. در پژوهش‌های پیشین به‌اندازه‌گیری دقیق و بیان درست زبری پرداخته‌شده است ولی این تحقیق با فرض مشخص بودن مقدار زبری، به دنبال شبیه‌سازی سطح ناپیوستگی آن است. درواقع هدف این پژوهش نوعی تحلیل برگشتی از بیان زبری است به‌عبارت‌دیگر در این تحقیق قرار است با معلوم بودن مقدار JRC، سطح ناپیوستگی آن شبیه‌سازی شود. از آن‌جا که چندین ناپیوستگی با پستی‌وبلندی‌های مختلف می‌توانند دارای مقدار زبری یکسانی باشند، بنابراین برای یک مقدار زبری مشخص نیز می‌توان ناپیوستگی‌های با پستی ‌و بلندی‌های مختلفی فرض کرد.


[i]Joint Roughness Coefficients

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Journal of Analytical and Numerical Methods in Mining Engineering
Volume 11, Issue 27
July 2021
Pages 55-66

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History

  • Receive Date: 12 July 2020
  • Revise Date: 20 October 2020
  • Accept Date: 15 February 2021

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