تاثیر کانی‌شناسی و اندازه دانه‌ها بر آستانه‌های آسیب گرانیت و دیوریت

نوع مقاله : مقاله پژوهشی

نویسندگان

1 گروه زمین شناسی مهدسی، دانشگاه تربیت مدرس

2 استاد گروه زمین شناسی مهندسی دانشگاه تربیت مدرس

3 گروه زمین شناسی مهندسی، دانشگاه تربیت مدرس

4 دانش آموخته گروه زمین شناسی مهندسی، دانشگاه تربیت مدرس

چکیده

ویژگی‌های تغییر شکل و شکست سنگ‌ها در نتیجه اعمال بار به مراحل مختلفی تقسیم شده‌اند که به‌وسیله آستانه‌های آسیب از هم تفکیک می‌گردند. با در نظر گرفتن پیدایش یا رشد ترک به عنوان یک ویژگی ماده، ویژگی‌های زمین‌شناسی سنگ‌ها را می‌توان به عنوان یک عامل کنترل کننده تغییرات در سطح تنش آستانه‌های آسیب در نظر گرفت. در این تحقیق آستانه‌های آسیب در دو سنگ گرانیت و دیوریت به کمک آزمایش تک‌محوری و انتشار آوایی تعیین شد. پس از تعیین آستانه‌های آسیب نمونه‌هایی از هر سنگ تا آستانه‌های آسیب مختلف بارگذاری شد و از آن‌ها مقاطع نازک فلورسانس به‌منظور بررسی تأثیر کانی‌شناسی و اندازه دانه‌ها و ترک خوردگی تهیه گردید. نتایج این تحقیق نشان داد که وجود کانی-های مقاوم به دلیل مقاومت در برابر ترک خوردگی سبب افزایش سطح تنش آستانه‌ آغاز ترک می‌گردد. با کاهش میانگین اندازه دانه‌ها قفل و بست بهتری در بین دانه‌ها ایجاد می‌شود و از طرف دیگر تعداد مرز دانه‌ها نیز افزایش پیدا می‌کند که سبب می‌گردد نیروی اعمال شده در سطح بیشتری توزیع گردد، درنتیجه کانی‌ها کمتر تحت تأثیر قرار گرفته و میزان ترک‌ در آن‌ها کم ‌شود که باعث افزایش سطح تنش آستانه‌ای آغاز ترک در سنگ‌های ریزدانه می‌گردد.

کلیدواژه‌ها


عنوان مقاله [English]

The effect of mineralogy and grain size on stress damage thresholds of granite and diorite

نویسندگان [English]

  • Shahram Ghasemi 1
  • Mashallah Khamechian 2
  • Mohammad Reza Nikudel 3
  • Ahmad Zalooli 4
1 Engineering Geology Department, Tarbiat Modares university
2 Prof. of engineering Geology Tarbiat Modares University
3 Engineering Geology Department, Tarbiat Modares university
4 Engineering Geology Department, Tarbiat Modares university
چکیده [English]

The deformation and failure properties of the loaded rocks are divided into different stages based on cracks' formation and growth. The different damage stress thresholds separate these stages. Considering the damage stress thresholds as a material property, geological properties of rocks can affect the damage stress thresholds. In this research, damage stress thresholds were identified for granite and diorite in the uniaxial compressive loading test with the help of the Acoustic Emission test (AE). Then fluorescence thin sections were prepared from the samples loaded to each damage stress threshold to investigate the effect of the mineralogy and the grain size. The results show that strong minerals increase the stress damage thresholds level due to the high cracking resistance. Furthermore, by decreasing the mean grain size, a better interlocking between the grains is created, and the number of grain boundaries increases. Therefore, the applied force has a higher surface to distribute. Consequently, minerals are less affected by the applied force; their crack density reduces, and crack initiation stress threshold increases.

کلیدواژه‌ها [English]

  • Damage Threshold
  • Acoustic Emission
  • Crack
  • Granite
  • Diorite
صادقیان، م.، 1373. بررسی پترولوژی سنگ‌های آذرین و دگرگون منطقه چشمه قصابان همدان. پایان نامه کارشناسی ارشد، دانشگاه تهران.
 
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