بررسی رفتار مکانیکی و دینامیکی دو نوع سنگ رسوبی آواری در آزمون سه محوره خودکنترل با توجه به بافت و ساخت آنها

نوع مقاله: مقاله پژوهشی

نویسندگان

1 گروه زمین شناسی دانشگاه اصفهان

2 گروه زمین شناسی، دانشگاه اصفهان، اصفهان، ایران

3 گروه مهندسی عمران، دانشگاه اصفهان، اصفهان، ایران

چکیده

تعیین پارامترهای مکانیکی و دینامیکی سنگ‌ها در شرایط متفاوت محیط آزمایشگاهی، دستگاهی و نمونه سنگ مورد آزمون صورت می‌گیرد. آزمون سه‌محوری یکی از آزمایش‌های مفید برای بررسی رفتار مکانیکی سنگ‌ها طی بارگذاری می‌باشد که اگر با استفاده از دستگاه‌های پیشرفته‌ی خودکنترل انجام گیرد، پارامترهای مهمی چون مقاومت مکانیکی، مدول تغییر شکل‌پذیری و تغییرات سرعت عبور موج حین بارگذاری را به طور پیوسته می‌توان تعیین نمود.
در این تحقیق ابتدا برخی ویژگی‌های فیزیکی و زمین‌شناسی دو نوع سنگ رسوبی آواری (ماسه‌سنگ و توف) مورد ارزیابی قرار می‌گیرد و سپس پارامترهای مکانیکی و دینامیکی آنها حین انجام آزمون سه محوره خودکنترل در شرایط مختلف فشار جانبی و محوری اعمال شده، بررسی می‌گردد. مقادیر پارامترهایی مانند مدول تغییرشکل‌پذیری، نسبت پواسون و سرعت عبور موج طولی و عرضی که معمولاً ثابت اعلام می‌گردد، با افزایش فشار محوری و جانبی در طول این آزمون تغییر می‌کند، زیرا رفتار نمونه حین آزمون از حالت الاستیک به پلاستیک تغییر پیدا می‌کند. بنابراین ارائه یک مقدار ثابت برای یک پارامتر نمی‌تواند منطقی باشد و باید شرایط تعیین آن را نیز در کنار عدد اعلام شده، مشخص نمود. نتایج آزمون سه محوری این تحقیق که به روش پلکانی ISRM انجام شده است، نشان می‌دهد مقادیر مقاومت، مدول تغییرشکل‌پذیری، نسبت پواسون و سرعت عبور موج طولی و عرضی برای نمونه ماسه سنگی بیشتر از نمونه آذرآواری می‌باشد که دلیل این تفاوت در ویژگی‌های فیزیکی و ساخت و بافت این دو نوع سنگ است. بازه‌ی تغییرات این پارامترها در دو نمونه سنگ مورد آزمون هم با یکدیگر متفاوت است.

کلیدواژه‌ها

موضوعات


عنوان مقاله [English]

Evaluation of mechanical and dynamical behaviors of two types of clastic sedimentary rocks at servo-controlled triaxial test according to their texture and structures

نویسندگان [English]

  • Mojtaba Heidari 1
  • Akbar Ghazifard 2
  • Mahmoud Hashemi 3
1 Department of geology, University of Isfahan
2 Department of Geology, University of Isfahan, Isfahan, Iran
3 Department of Civil Engineering, University of Isfahan, Isfahan, Iran
چکیده [English]

Determining the mechanical and dynamic parameters of the rocks under different environmental conditions of laboratory, device, and rock samples tested. Triaxial test is one of the most useful tests for mechanical behavior of rocks, which be done by advanced servo-controlled devices, can determined important parameters such as mechanical strength, modulus of deformeabilities and variations in the velocity of the wave during loading continuously.
In this paper, at first some of the physical and geological characteristics of two types of clastic rocks (sandstone and tuff) evaluated, and then their mechanical and dynamic parameters determined during servo-controlled triaxial test in different conditions of lateral and axial stress studied. The values of parameters such as modulus of deformeability, the poisson's ratio, and longitudinal and transverse wave velocities, which are usually stated constant, change with increasing axial and lateral stresses during the test, because the sample's behavior changes from elastic to plastic during test. Therefore, providing fixed value for a parameter can't be logical and must specify the conditions for its determination along with the declared number. The results of triaxial test of this study, carried out by the ISRM standard method, show that the resistance values, the modulus of deformeability, the poisson's ratio and the wave velocity of the longitudinal and transverse waves for the sandstone sample are higher than that of the pyroclastic sample, due to the difference in physical properties and the structure and texture of these two rocks. The range of variations of these parameters is different in two specimens.

کلیدواژه‌ها [English]

  • servo-controlled triaxial test
  • clastic sedimentary rocks
  • Mechanical Strength
  • deformeability
  • Wave velocity
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