ارزیابی شاخص شکنندگی S20 سنگ آهک و تاثیر عوامل موثر بر آن در حالت خشک و اشباع

نوع مقاله: مقاله پژوهشی

نویسندگان

1 گروه زمین شناسی، دانشکده علوم، دانشگاه فردوسی مشهد، مشهد، ایران

2 استاد/ گروه زمین شناسی، دانشکده علوم، دانشگاه فردوسی مشهد، مشهد، ایران

چکیده

شکنندگی یکی از مسائل مهم در حفاری سنگ است. تاکنون روش های مختلفی برای تعیین شکنندگی سنگ معرفی شده است اما روشی برای اندازه گیری آن به عنوان استاندارد مطرح نشده است. در این مقاله، یک مطالعه تجربی برای ارائه روشی قابل اعتماد برای پیش بینی شاخص شکنندگی S20 صورت گرفته است. آزمایش تعیین شاخص شکنندگی S20 برای 35 بلوک سنگ آهک برداشت شده از نقاط مختلف ایران، در حالت خشک و اشباع انجام شد. به علاوه، خصوصیات فیزیکی (چگالی خشک، تخلخل، مقاومت الکتریکی، عدد سختی بازگشتی اشمیت و درصد جذب آب)، مکانیکی (مقاومت فشاری تک محوری و شاخص بار نقطه ای) و دینامیکی (سرعت موج برشی و تراکمی) اندازه گیری شد. در نهایت، رده بندی نمونه ها بر اساس مطالعات سنگ شناسی و کانی شناسی انجام شد و مطالعات آماری برای هر رده صورت گرفت. بر اساس نتایج، پیش بینی شاخص شکنندگی S20 بر اساس رده بندی ارائه شده از اطمینان بالایی برخوردار است. به علاوه، با بررسی شکنندگی نمونه ها در حالت خشک و اشباع مشخص شد که وجود کانی رسی مونتموریلونیت باعث افت شکنندگی و وجود ریزترک های درون دانه ای و تخلخل بالا باعث افزایش مقدار شکنندگی در حالت اشباع نسبت به خشک می شود.

کلیدواژه‌ها


عنوان مقاله [English]

Investigation S20 brittleness index of limestone and effective parameters on it at dry and saturated states

نویسندگان [English]

  • Sajad Safari Farrokhad 1
  • Gholam Reza Lashkaripour 2
  • Nasser Hafezi Moghaddas 2
1 Department of geology, Faculty of science, Ferdowsi University of Mashhad, Mashhad, Iran
2 Professor Department of geology, Faculty of science, Ferdowsi University of mashhad, Mashhad, Iran
چکیده [English]

Brittleness is an important problem in rock boring. So far, various methods have been introduced for determining rock brittleness but no method has yet been standard to measure it. In this paper, an empirical study was done to provide a reliable method for predicting the S20 brittleness index. The S20 brittleness test was done for 35 limestone blocks pick out from different parts of Iran in dry and saturated state. In addition, physical (dry density, porosity, electrical resistivity, Schmidt rebound hardness number and water absorption), mechanical (uniaxial comprehensive strength and point load index) and dynamical properties (P and S wave velocity) was measured. Finally, the classification of the samples was done based on the studying of petrography and mineralogy and statistical studies were done for each class. According to the results, predicting S20 based on the provided classification has a high degree of certainty. In addition, by studying the brittleness of the samples in dry and saturated state, it was determined that the presence of Montmorillonite clay mineral causes a decrease of brittleness and the presence of intergranular micro cracks and high porosity leads to an increase brittleness in the saturation state relative to dry state.

کلیدواژه‌ها [English]

  • S20 brittleness index
  • Rock boring
  • Montmorillonite
  • Petrography
  • Limestone

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