A new approach to rock brittleness and its usability at prediction of drillability

Özfirat M.K. | Yenice H. | Şimşir F. | Yarali O.

Article | 2016 | Journal of African Earth Sciences119 , pp.94 - 101

Rock brittleness is one of the most important issues in rock drilling and cutting. The relations between drillability and brittleness will assist engineers in excavation works. The demand for representative rock parameters related to planning of underground excavations is increasing, as these parameters constitute fundamental input for obtaining the most reliable cost and time estimates. In rock cutting mechanics, the effects of the rock and brittleness on the efficiency of drilling and excavation are examined by many researchers. In this study, 41 different rock types were tested in laboratory to investigate the relations between t . . .he drilling rate index and different brittleness values. Firstly, the relations defined in literature are tested. Strength tests are made according to International Society for Rock Mechanics standards. In addition Norwegian University of Science and Technology standards are used to determine drilling rate index. Then, a new brittleness index is proposed which is the arithmetic average of uniaxial compressive strength and tensile strength. Considering the regression analysis carried out, it was seen that the proposed formula showed good correlation for these samples handled in this study. As a result of this study, a high correlation is obtained between the proposed index and drilling rate index values (R:0.84). The results are found to be at least reliable as well as other brittleness equations given in literature. © 2016 Elsevier Ltd Daha fazlası Daha az

The effect of mechanical rock properties and brittleness on drillability

Yarali O. | Soyer E.

Article | 2011 | Scientific Research and Essays6 ( 5 ) , pp.1077 - 1088

This paper examines the relationships between drilling rate index (DRI) and some mechanical properties of rocks in order to evaluate the effect of properties of strength, indexes, and brittleness of rock on rock drillability. For this purpose, some index properties (Shore scleroscope hardness (SSH), and point load strength (PLS) and geomechanical (uniaxial compressive strength (UCS) and Brazilian tensile strength (BTS)) values of 32 sedimentary, igneous and metamorphic rock samples were determined. Then, the brittleness concepts which use the uniaxial compressive strength and tensile strength of rocks were determined for calculation . . .s. Four different brittleness concepts were used in the statistical analysis. In this study, a new brittleness concept (B4) which was found as a result of laboratory studies has proposed by authors for percussive drilling and rotary drilling. The relationships among of DRI and both mechanical rock properties and brittleness concepts were evaluated using regression analysis and statistical methods. As a result, decreasing linear relationships were found among of DRI and uniaxial compressive strength, shore scleroscope hardness, diametral and axial point load strength. In additional to meaningful relations were obtained between drillability of rocks and brittleness of B3 and B4. ©2011 Academic Journals Daha fazlası Daha az

The drillability assessment of rocks using the different brittleness values

Yarali O. | Kahraman S.

Article | 2011 | Tunnelling and Underground Space Technology26 ( 2 ) , pp.406 - 414

The brittleness is a fundamental rock property and effective in drilling and rock excavation. Knowing the relations between the drillability and the brittleness will help the rock engineers. For this reason, to investigate the relations between the drilling rate index (DRI) and the different brittleness values, 32 different rock types were tested in the laboratory. Uniaxial compressive strength and tensile strength were determined for the brittleness calculations. The brittleness of B3 (the ratio of compressive strength minus tensile strength to compressive strength plus tensile strength), and the brittleness of B8 (the half of the . . .product of compressive strength and tensile strength) were calculated from the test results. In addition, Sievers' J-miniature drill test and the brittleness test were carried out and DRI values were calculated. Then, B3 and B8 were correlated with DRI values. A good correlation between DRI and the brittleness of B3 could not be found. However, a strong exponential relation between DRI and the brittleness of B8 was found. Comparing the results with the literature showed that there was an agreement between this study and previous studies. It can be concluded that B8 can be used for the assessment of rock drillability. © 2010 Daha fazlası Daha az

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