Tek Eksenli Sıkışma Dayanımının Farklı Boy/Çap Oranlarındaki Örneklerden Belirlenmesi Yaklaşımının Değerlendirilmesi

Abstract

One of the parameters affecting the uniaxial compressive strenght (UCS) of rock in laboratory is the lenght to diameter ratio (L/D) of rock specimens. It is known from the studies conducted by different researchers that if the L/D ratio changes the UCS values also changes. L/D ratios of rock specimen used for the UCS test is suggested in the range of 2.0-2.5 and 2.5-3.0 by the American Society for Test Standards (ASTM) and International Society for Rock Mechanics (ISRM), respectively. Besides, while the UCS values also determined from the samples with 2.5 L/D ratio are accepted as standard in some correction equations proposed for UCSs, which are determined from cores with small L/D ratio, this ratio is selected as 2.0 in some equations. By considering these differences, a method which allows the selection of different L/D ratios depending on the rock type and the correction of UCSs obtained from experiments with specimens having lower L/D ratios (in the thesis study, it is called as L/D CLASS method) was proposed by a researcher group. Given the differences in the L/D ratios specified in international suggested methods and standards, the availability of the L/D CLASS method becomes important. For this reason, in this thesis study, it is aimed to investigate the validity of the mentioned method.

For this purpose, block samples belonging to 10 different rocks of sedimantary, magmatic and metamorphic origin were obtained from stone producers in different parts of Turkey. Experiments in order to determine some physical and mechanical properties of these rock samples and UCS experiments were carried out on specimens with L/D ratios of 1.0, 1.25, 1.50, 1.75, 2.0, 2.5 and 3.0 in the laboratory. The results obtained were evaluated in accordance with the L/D CLASS method and the UCSs determined from this method were compared with the UCSs (UCSISRM) determined in accordance with the ISRM suggested methods with the rid of statistical analyses. In addition, UCS values for each rock type were also determined indirectly by performing Schmidt hammer, Point load strenght index, Block punch strenght index and Needle penetration strenght index tests. The variation in the results from UCSISRM and these of the UCS determined according to the L/D CLASS method from cores with L/D<2 were compared. As a result, it was seen that the UCSs determined from the cores with the selected L/D ratios using the L/D CLASS method were very similar to the UCSISRM values and the method could be used for the rock samples used in this. In addition, it was concluded that the results obtained from this method were much more similar to the UCS’s determined by considering ISRM suggested method than those obtained from the index tests, and this method should be preferred instead of index tests for rocks from which specimens with up to the ratio of L/D=1.0 can be taken.