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Öğe Abrasion wear characterization of some selected stone flooring materials with respect to contact load(Elsevier Sci Ltd, 2012) Karaca, Z.; Yilmaz, N. Gunes; Goktan, R. M.Abrasion of stone flooring materials under the influence of foot traffic is mainly a function of the load exerted on them by fine solid particles. This paper presents a study of the abrasion behavior of some natural stone flooring materials when subjected to wear under varying contact loads. Abrasion wear tests were performed on a Bohme apparatus which is widely used in the construction industry for determining flooring suitability of stone tiles. Contact loads ranging from 100 to 500 N were applied for each tested stone material, while keeping the other operational parameters constant. In the case of carbonate stone materials, abrasion wear rate was found to be linearly proportional to the applied load. The granites, however, exhibited a non-linear abrasion wear behavior, not conforming to Archard's well-known classical wear law. It was also observed that, in some cases, changes in the applied load could be an influencing factor in the ranking of flooring materials with respect to abrasion wear rate. (C) 2012 Elsevier Ltd. All rights reserved.Öğe Influence of rock cradle block geometry on rebound hardness(Springer Heidelberg, 2016) Yilmaz, N. Gunes; Goktan, R. M.; Yavuz, A. B.; Karaca, Z.The Schmidt hammer (SH) testing of cylindrical rock cores requires the use of a cradle block (core holder) to hold the cores firmly during the test. For this purpose, the related International Society for Rock Mechanics (ISRM)-suggested method and American Society for Testing and Materials (ASTM) standard suggest the use of an 'arch-shaped' or a 'V-shaped' cradle block. However, there is little or no detailed quantitative information in the literature regarding the potential influence of cradle block type on the measured rebound values (R values). With this in view, an investigation was carried out regarding the influence of cradle block geometry on R values, by employing the two cradle blocks specified in the preceding Standards. Using an L-type Digi-Schmidt hammer, SH tests were performed on NX-size cylindrical cores of 20 different rock varieties, both in 'oven-dry' and 'wet' state. Although the observed differences were usually small, results showed that the magnitudes of the mean rebound values determined in the arch-shaped block (R (A)) were higher than those determined in the V-shaped block (R (V)), except in one case. For the oven-dried samples, lowest and highest differences between the means of R (A) and R (V) values were 0.37 and 5.92, respectively. In the case of wet samples, the differences ranged from a low of 0.33 to a high of 4.70 in R-units. Statistically significant positive linear correlations were observed between R (A) and R (V) values, although the degree of correspondence was relatively lower for rocks having uniaxial compressive strength < 50 MPa. The results of additional SH tests carried out on two different engineering materials also indicated that higher mean rebound values could be attained in the arch-shaped block. The results of the present study did not confirm the findings of a previous study where it was found that the V-shaped cradle block gave consistently higher mean rebound values than the arch-shaped one. The possible reasons for this discrepancy were discussed.Öğe Remote sensing in management of mining land and proximate habitat(Southern African Inst Mining Metallurgy, 2012) Koruyan, K.; Deliormanli, A. H.; Karaca, Z.; Momayez, M.; Lu, H.; Yalcin, E.Although remote sensing technology has been available for many years, it has rarely been used for monitoring mining activity. Recent studies indicate that remote sensing is also a valuable tool for managing and planning certain aspects of the mining operation. In this paper, we examine areal expansion of marble quarries and the affected vegetation over a period of 10 years in the Mugla region in Turkey, using geographic information system (GIS) and remote sensing (RS) techniques. Images captured by ASTER Level 3A01 (3D Ortho Data Set), Landsat 5, and Landsat 7 satellites between 2001 and 2009 were used for the analysis. Changes in the natural vegetation as a function of the production level in the marble quarry were calculated using the normalized difference vegetation index. According to the study results, land cover and natural vegetation decreased by less than 3 per cent and 1 per cent respectively between 2001 and 2009, following an upsurge in mining activity in the region.Öğe The effects of strength parameters on slope failure mechanisms in weak rocks(Crc Press-Balkema, 2016) Dinc, O.; Karaca, Z.; Isik, N.This research project investigates the planar failure mechanisms of rock slopes by using PFC2D numerical code based on the distinct element methods. The aim of this work is to evaluate further the role of persistence of discontinuities (joints) that controls the planar failure mechanisms of slopes. Three types of rock materials were modeled by using bonded particle model procedures in PFC. The results show that the location of the rock bridges predominantly affect the failure mechanisms of rock slopes as well as the discontinuity length. All rock materials (e.g limestone, claystone and gypsum) with UCS values under 25 MPa, begin to fail initially by the tensile stresses around the rock bridge zones then those will eventually develop tension cracks.
