بررسی اثر مقیاس بر پارامترهای هندسی سطوح درزه سنگ

نوع مقاله: مقاله پژوهشی

نویسندگان

1 گروه معدن، دانشگاه سیستان و بلوچستان

2 گروه مهندسی مکانیک سنگ، دانشگاه تربیت مدرس

10.29252/anm.8.15.99

چکیده

بر اساس مطالعات انجام شده، مشخص شده است که رفتار مکانیکی درزه‌های سنگی می‌تواند به عنوان تابعی از مقیاس تغییر کند. در چهل سال گذشته، مطالعات وسیعی بر روی اثر مقیاس بر روی رفتار مکانیکی درزه‌های سنگی انجام شده است. بسیاری از این مطالعات نتایج متناقضی را در بر داشته است. بنابراین ماهیت و سازوکار اثر مقیاس بر رفتار مکانیک درزه‌های سنگی هنوز به طور کامل شناخته نشده و نیاز به مطالعات بیشتری دارد. یکی از مهم‌ترین پارامترهایی که بر روی رفتار برشی درزه‌ها تاثیر گذار است خصوصیات هندسی سطوح آنها است. بنابراین بررسی پارامترهای هندسی سطوح درزه با در نظر گرفتن اثر مقیاس بر آنها تا حد زیادی می‌تواند تبیین کننده رفتار وابسته به مقیاس درزه‌ها باشد. در پژوهش حاضر سه سطح طبیعی درزه با هندسه‌های متفاوت و با ابعاد بیش‌تر از 2500 سانتی‌مترمربع از طبیعت انتخاب شده‌اند. برای ابعاد 50 × 50 میلی‌مترمربع تا 500 × 500 میلی‌مترمربع، پارامترهای هندسی مهم درزه محاسبه شده و اثر مقیاس بر این پارامترها و تغییرات مقادیر آن‌ها نسبت به مقیاس مورد بررسی قرار گرفته است. بررسی‌های انجام شده نشان می‌دهد اثر مقیاس بر پارامترهای مختلف هندسی یکسان نبوده و بسته به نوع هندسه درزه و چگونگی توزیع پارامترهای زبری اولیه و ثانویه سطح، نتایج متفاوتی را به همراه خواهد داشت. پارامترهای زاویه‌ای سطح درزه در مقیاس بیشتر از‏‎‎‏400 سانتی‌مترمربع تقریبا مستقل از مقیاس ‏خواهند شد. اما پارامترهای ارتفاعی سطح درزه، برای سطوحی که زبری درجه اول در آنها ‏بیش‌تر باشد، با افزایش مقیاس (حداقل تا‏ 2500 سانتی‌مترمربع) افزایش می‌یابند. ‏

کلیدواژه‌ها

موضوعات


عنوان مقاله [English]

The effect of scale on the geometric parameters of the rock joint surfaces

نویسندگان [English]

  • Mohamad Javad Azinfar 1
  • Abdolhadi Ghazvinian 2
  • Hamid Reza Nejati 2
1 Dept. of Mining, University of Sistan and Baluchestan
2 Tarbiat Modares University
چکیده [English]

Summary
In this study, three different natural joint geometries in dimensions greater than 2500 cm2 were selected from the field. The geometric parameters of the surface joints have been calculated from the scale of 50 × 50 mm2 to 500 × 500 mm2 and the effect of scale on these parameters and their variations with scale has been discussed.
 
Introduction
The scale dependency of discontinuity surface roughness and shear strength has been investigated by many other researchers over the last three decades. Many of these studies have produced conflicting results. Some studies have shown a decrease in strength and roughness with increasing discontinuity size. Other studies have shown the existence of positive scale effects, a combination of positive and negative scale effects, or no scale effect. The present study attempts to investigate the effect of scale on the geometrical properties of rock joints.
 
Methodology and Approaches
In this study, three natural smooth, undulating and stepped rock joints were prepared and their surfaces were scanned by 3D optical scanner. The surfaces were digitized and the geometric parameters were calculated by the code written in Matlab software. The geometric parameters were calculated for the square widows that were centered at the same locations and were measured from 50 × 50 mm2 to 500 × 500 mm2.
 
Results and Conclusions
The results showed that the effect of scale on various geometric parameters are not the same and will have different results depending on the distribution of primary (waviness) and secondary (unevenness) roughness. The angular parameters of rock joint surfaces, in the scale of greater than 400 cm2, are independent of scale. However the amplitude parameters of rock joint surfaces, in the surfaces with dominant waviness, increase with increasing of scale (at least up to 2500 cm2)

کلیدواژه‌ها [English]

  • Scale effect
  • Geometric characteristics of joint surfaces
  • Geometric parameters of the surfaces
  • 3D scannig of rock joint
  • 3D Optical scanner
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