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    Experimental studies using a new portable linear rock cutting machine and verification for disc cutters
    (Pergamon-Elsevier Science Ltd, 2021) Comakli, Ramazan; Balci, Cemal; Copur, Hanifi; Tumac, Deniz
    This study aims at verifying the experimental results of a newly developed portable linear rock cutting machine (PLCM) and its usability for proper selection, design and predicting performance of TBMs instead of full-scale rock cutting machine. PLCM minimizes some of the disadvantages of full-scale linear rock cutting machine (FLCM) such as requiring experienced manpower to run the tests, large blocks of rock samples, which are usually difficult to obtain and expensive, and time consuming procedures. Relieved and unrelieved cutting tests at different depths of cut are performed in this study on different rock samples with the PLCM by using a mini-scale constant cross-section (CCS) disc cutter having a diameter of 145 mm and a tip width of 4.7 mm and the FLCM by using a real-life CCS disc cutter having a diameter of 432 mm and a tip width of 12 mm. Line spacing is 20 mm for mini scale disc cutter and 60-80 mm for real-life disc cutter in cutting tests in relieved mode. The results from both of the experimental devices are correlated for using prediction of cutting performance parameters of FLCM, which is commonly preferred and well-proven testing device for predicting the performance of any type of mechanical miner excavating hard rock. Then, another set of rock sample is obtained from Uskudar-Umraniye-Cekmekoy (UUC) metro tunnel construction site using EPB TBMs, of which their field performance (penetration and/or cutting rate, specific energy) and operational parameters (TBM thrust, cutterhead torque, power and rotational speed) are recorded. Based on the PLCM tests performed on the samples obtained from the field, the performance of the TBM is estimated theoretically (deterministically) and compared with the realized field performance to verify the results of the PLCM tests. The results indicate that the experimental cutting performances of the PLCM and the FLCM are well correlated and the PLCM can be used for predicting performance, design and selection of TBMs excavating hard rocks. Additional studies are required for developing more reliable models for predicting excavation performance.
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    Performance prediction of roadheaders in metallic ore excavation
    (PERGAMON-ELSEVIER SCIENCE LTD, 2014) Comakli, Ramazan; Kahraman, Sair; Balci, Cemal
    Using mechanical miners such as roadheaders may be a solution to increase the production rate and to decrease the costs in metallic mines. In this study, the performance prediction and cutter consumption of roadheaders were investigated for the eight different ore types. Small-scale linear cutting tests, Cerchar abrasivity tests and physico-mechanical tests were carried out on the ore samples collected from the site. The instantaneous cutting rates of a selected roadheader were calculated using specific energy (SE) values and compared to the previous models. The amount of cutter consumption was also calculated for each ore type and it was seen that the estimated cutter consumption values for the tested ores are generally lower than the proposed economical upper limit. Since only the performance prediction and cutter consumption of roadheaders were investigated for the excavation of ores in the current study, analyzing all mining operations is necessary for the adaptation of roadheader excavation to a mine. Simple and multiple regression models were also derived for the estimation of SE from the ore properties. A significant practical model including the Schmidt hammer value and density of ores was produced from the multiple regression analysis. This regression model can be reliably used for the estimation of SE especially for the preliminary studies. (C) 2013 Elsevier Ltd. All rights reserved.
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    Performance prediction of roadheaders in metallic ore excavation (vol 40, pg 38, 2014)
    (PERGAMON-ELSEVIER SCIENCE LTD, 2014) Comakli, Ramazan; Kahraman, Sair; Balci, Cemal
    [Abstract Not Available]
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    The effect of mineralogy on the microwave assisted cutting of igneous rocks
    (Springer Heidelberg, 2022) Kahraman, Sair; Sarbangholi, Faraz S.; Balci, Cemal; Fener, Mustafa; Karpuz, Ceyhun; Comakli, Ramazan; Unver, Bahtiyar
    Hard rocks can be excavated difficultly by some mechanical miners such as roadheaders. Tunnel boring machines (TBMs) can excavate hard rocks, but the cost is high due to low advance rate and high tool wear. The difficulties in hard rock excavation can be overcome by exposing hard rocks to microwave energy while cutting. This study investigates influence of mineralogy on the microwave assisted cutting of igneous rocks. The normal and cutting forces were measured during the cutting tests, and the specific energy values were calculated. The optimum specific energy (SEopt.) values reduce quite steadily with the increasing microwave power. The SEopt. of some tested crystalline rocks first increases at the low power (3 kW) and then decreases at the high power (6 kW). The losses in the SEopt. range from 22.5 to 38.7% at the power of 6 kW. The equations were also developed for the estimation of the SEopt. loss. Concluding remark is that the same rock types may be affected differently by microwave energy because of the different mineral types and percentages, and thus they behave diversely under cutting tests. The derived equations will be useful for the prediction of the SEopt. loss due to the microwave treatment.