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    Assessment of Scale Effects on Uniaxial Compressive Strength in Rock Salt
    (GEOLOGICAL SOC AMER, INC, 2009) Ozkan, I.; Ozarslan, A.; Genis, M.; Ozsen, H.
    In mining design studies, the determination of the in situ strength parameters of a rock mass is difficult, expensive, and time consuming. Therefore, designers prefer an empirical approach, which has been developed based on laboratory studies. However, the scale effect on uniaxial compressive strength (UCS) is an important parameter, particularly for special materials like coal and rock salt. The accurate determination of UCS under laboratory conditions makes it possible to reliably estimate in situ strength. In this study, the change in UCS attributable to scale was determined for Nevsehir-Gulsehir rock salt, and the results are presented to emphasize the importance of the scale effect on failure phenomena in rock salt under uniaxial compression. With statistical analysis, the critical height/diameter and height/width ratios were determined to be 1.5 for core specimens and 2.0 for prismatic specimens.
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    Characterization of jointed rock masses for geotechnical classifications utilized in mine shaft stability analyses
    (PERGAMON-ELSEVIER SCIENCE LTD, 2015) Ozkan, I.; Erdem, B.; Ceylanoglu, A.
    In the Divrigi open pit iron mine in Turkey, extracted ore is initially crushed in an underground chamber. This chamber was previously located 54 m below the bottom level of the mine, which was linked by a vertical shaft Because of the progression in the mine operations, the mine management decided to shift the chamber to a depth of 264.15 m below the surface. A borehole called as YNK-3, which was no closer than 15 m to the existing shaft that was 4 m in diameter and 54 m in length, was drilled to a vertical distance of 264.15 m. Although the fist 54 m was drilled in a coreless manner, the drill cores obtained from the remaining 210.15 in were used in the rock mass characterization studies tot the design of the shaft support. The rock tbrmations encountered during shaft sinking, which were generally jointed rock masses, were classified into structural regions and domains for geological and geotechnical definition. Initially, the original rock mass rating (RMR) and quality (Q) systems were used for rock mass characterization, but difficulties were experienced in determining a number of input parameters required, particularly by the RMR system. A comprehensive examination of the drawbacks encountered directed us to the modified RMR (M-RMR) system. In this paper, the original (RMR and QJ and modified (M-RMR) rock mass classification systems are compared in a detailed discussion of our results. In addition, the classification results were tested using the Hoek-Brown failure criterion to compare the ratings presented by classification systems. (C) 2014 Elsevier Ltd. All rights reserved.
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    Mathematical approach for the analysis of in situ measurements in unstable slopes: A study based on the cases from coal mines in Turkey
    (CRC PRESS-TAYLOR & FRANCIS GROUP, 2014) Ozkan, I.
    Eskihisar, Orhaneli, and Ilgin are important lignite open-pit mining regions in Turkey, which in the last 10 years have experienced problems with slope stability, according to long-term, in situ measurements. In this study, a mathematical model based on results of these in situ measurements was developed after statistical analysis, during which high statistical regression R-2 values were obtained by using SPSS v16.0. The velocity and acceleration behaviors were then derived by the model developed. The critical moments during unstable periods versus deformation curves were detected by the derived velocity and acceleration curves.
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    A new approach for evaluation of in situ inclinometer measurements based on two cases in Turkey
    (CRC PRESS-TAYLOR & FRANCIS GROUP, 2014) Mesutoglu, M.; Ozkan, I.
    The studies presented in this paper were carried out in two different regions. They are TKI-GLI-BLI Orhaneli lignite open pit mine region and Konya-Cumra agricultural basin, respectively. In Orhaneli mine site, to monitor deformations in 9 boreholes, inclinometer measurements were made approximately 14 times for 215 days. Similarly, in Cumra agricultural basin, using 11 boreholes established in site, these measurements were made 7 times for 784 days. In the evaluation of the measurement results, the presences of certain problems have been identified. To utilize in the evaluation studies of the inclinometer measurement results, a new approach was developed. The approach used in the project studies was presented in this paper.