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Öğe Effect of water saturation on Cerchar abrasivity index (CAI) of clay-rich rocks at different scratch lengths(Elsevier Science Sa, 2024) Comakli, Ramazan; Aldalahali, Abdullah Mhmood JumahPredicting the cutter consumption rate of mechanical excavators using the Cerchar abrasivity index (CAI) results is possible. However, changing operational parameters in the field may cause differences between the estimated cutter consumption rate based on CAI test results and the real cutter consumption rate observed in the field. One of the essential parameters in the field that affects the cutter consumption rate is the increase in the water content of the excavated rocks. In theory, an increase in the water content of rocks is expected to reduce their abrasivity. In addition, the prediction of cutter consumption rate is based solely on CAI test results conducted on dry surfaces. However, especially during the excavation of low-strength clay-rich rocks, the excavated rock material can adhere to the cutters and block them, leading to a higher cutter consumption rate than initially predicted. This study aims to analyze the rock-pin interaction in CAI tests conducted on wet surfaces of clay-rich rocks and investigate the effect of water saturation on CAI at different scratch lengths. CAI tests were conducted on dry and wet surfaces of 20 clay-rich rocks with low strength at 10, 30, 50, and 70 mm scratch lengths, respectively. The relationships between the CAI test results obtained on dry and saturated rock surfaces were statistically analyzed for each scratch length. A positive linear correlation was found between CAI values obtained on dry (CAIDry) and saturated surfaces (CAISat) at each scratch length. The percentage variations in CAI values at each scratch length were analyzed in detail. It was found that 90 % of samples have higher CAIDry than CAISat at 10 mm scratch length. However, it was observed that as the scratch length increased, the relationship between the CAI values obtained in dry and saturated conditions changed, and the proportion of samples with CAIDry higher than CAISat decreased to 65 %, 55 %, and 25 % at scratch lengths of 30 mm, 50 mm, and 70 mm, respectively. In CAI tests conducted on saturated surfaces, it was observed that the excavated rock material adhered to the test pins, and as the scratch length increased, the increase in CAISat values was considered to be due to this situation. This study revealed the importance of considering the adhesion potential of rocks to cutters at water-saturated conditions for the accurate prediction of cutter consumption in the excavation of clay-rich rocks.Öğe Effects of changing water content of clay-content rocks on field cutter consumption rate of roadheaders: a case study of porous ignimbrites(Springer Heidelberg, 2024) Comakli, Ramazan; Bayramov, JahidThe changing formation characteristics during excavation can cause a higher cutter consumption rate (CCR) of mechanical excavators than theoretically estimated before the project begins. This study investigates the adhesive potential of clay-content porous ignimbrites in increasing water content and their effects on the CCR of roadheaders. For this purpose, the actual field CCR data of roadheaders were recorded for ten cold storage caverns (CSC) projects during the excavation in dry and wet conditions. Then, laboratory tests were carried out on the rock samples collected from project areas. CCRs of roadheaders were theoretically estimated based on the Cerchar abrasivity index of rocks using three different empirical models. The laboratory test results showed that increasing water content reduces the abrasivity and strength of the rocks. The theoretically estimated results also showed that CCR is to be less under saturated conditions. However, actual field data revealed higher CCRs for all CSC projects in wet conditions. Therefore, the adhesion potential of rocks in different water contents was analyzed, and positive relationships were obtained between the field CCR in wet conditions and the adhesion potentials of excavated rocks with 15%, 20%, and 25% water content. New equations were developed to estimate the CCR of roadheaders, especially in excavating rocks that have an adhesive potential to cutters, such as clay-content rocks. It has been concluded that for an accurate CCR estimation, more than theoretical calculations will be required, and changing formation conditions should also be analyzed in detail.Öğe Effects of the physico-mechanical properties of low-strength pyroclastic rocks on cutter wear of roadheaders(Elsevier Science Sa, 2019) Comakli, RamazanConstruction projects that use mechanical excavators such as tunnel boring machines (TBM) or roadheaders generally result in high costs due to cutter wear. Cold storage caverns (CSC) are one area where roadheaders are used, but excavations of CSC5 show different characteristics than tunneling and mining excavations. The effects of the physico-mechanical properties of low - strength, pyroclastic rocks (tuffs) on the wear of roadheader cutters were investigated during the excavation of CSC5 in the Cappadocia region of Turkey. The excavated tuffs containing 13-19% quartz had low uniaxial compressive strength (UCS), ranging from 3.14 to 13.17 MPa. Field excavation performance parameters were continuously recorded for one week on two similar roadheaders and 14 different CSC5 projects. The average field cutter consumption rate (CCRField), defined as cutter material loss per excavation of 1 cubic meter rock, was calculated for each CSC. Physico-mechanical tests were performed on the rock samples collected from the CSC project areas. Additionally, sieve analyses were performed on the excavated rock materials to determine their coarseness index (CI) and mean particle size (d((50))). The calculated average CCR values were statistically analyzed with some physico-mechanical properties of rocks, in-situ Schmidt hammer hardness (SHHIn-situ), CI and d((50)). Negative correlations were found between CCR and each of the UCS values, Brazilian tensile strength (BTS), point load strength (I-s(50)), SHHIn-situ CI and d((50)), and a positive linear correlation was found only with the water contents of the rocks. All of these relationships were found to be dependent on crushing of the excavated materials in fine sizes, blockage of cutters by filling of the fine materials into the space between the holder and cutters and adherence of fine materials to the cutters and cutterhead, as affected by water/moisture and clay contents. This study, whose results apply to studies in the Cappadocia region of Turkey, showed that the CCRField of roadheaders decreased as the strength of rocks increased. These relationships specifically apply to easy-cutting tuffs with very low strength and high water content.Öğe 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, DenizThis 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.Öğe Investigating the effects of water saturation on the crushability of rocks used in aggregate production(Springer Heidelberg, 2023) Comakli, RamazanMany studies investigate the effects of increased water content on the strength parameters of rocks. However, there is no study on the effects of water saturation on the crushability of rocks. While rock samples fail under static loading in strength tests, there are dynamic loads in the crushing process. Therefore, the effects of water saturation on the crushability of rocks cannot be expected to be the same as its effects on the other strength parameters. In this study, the effects of water saturation on the crushability of rocks in three different size ranges were investigated for nine different rock samples. First, rocks' physical-mechanical properties and brittleness indices were determined in dry and saturated conditions. Then, to determine the crushability indices (CI) and particle sizes (d(50) and d(80)), test rocks were prepared in three different size ranges. All test rocks were crushed by a jaw crusher, respectively, and CI, d(50), and d(80) values were determined. The relationships between the strength parameters, brittleness indices, CI, and particle sizes of rocks obtained in dry and saturated conditions were statistically analyzed. The results revealed that the effects of water saturation on the crushability of rocks are different from its effects on the other mechanical behaviors of rocks. On the other hand, it was observed that the effect of water saturation is not the same in all size ranges, and although the crushability of rocks in the medium and fine size range increased, that of the rocks in the coarse size range decreased.Öğe Investigation of the relationships between basic physical and mechanical properties and abrasion wear resistance of several natural building stones used in Turkey(Elsevier, 2021) Mohammed, Abdualrahman Ali Adam; Fener, Mustafa; Comakli, Ramazan; Ince, Ismail; Balci, Mehmet Can; Kayabali, KamilFrom the past to the present, natural building stone has been used as construction materials in important buildings, architectural works, and civil engineering projects due to its characteristics, which include hardness, durability, decorative appearance, and easy shaping. Nevertheless, there are several significant properties such as abrasion resistance that limit its usability. Since natural stone wears over time, its abrasion wear resistance should be determined before use. One of the most widely used methods for testing to determine the abrasion resistance of natural stone is the Bohme abrasion test. However, this method has a number of disadvantages including sample preparation, labor, and difficult test procedures. Moreover, this testing device is not typically available in all laboratories or analysis centers. The aim of this study was to establish equations based on the basic physical and mechanical properties of natural building stone in order to estimate the abrasion wear resistance. Therefore, the relationships between the Bohme abrasion test results and the basic physical and mechanical properties such as porosity, percentage of water absorption by weight, dry unit weight, density, and uniaxial compressive strength of 22 different natural building stones, collected at different locations in Turkey, are analyzed statistically. Simple and multiple regression analyses were performed to identify the best relationships, and all the obtained equations were assigned correlation coefficient (R-2) values. The results indicated that there are strong correlations between the Bohme abrasion test results and the basic physical properties of natural building stone, and a moderate relationship with uniaxial compressive strength.Öğe Performance prediction of roadheaders in metallic ore excavation(PERGAMON-ELSEVIER SCIENCE LTD, 2014) Comakli, Ramazan; Kahraman, Sair; Balci, CemalUsing 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.Öğe 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]Öğe Predicting the noise level during sawing of carbonate rocks from the P-wave velocity(International Commission for Acoustics (ICA), 2019) Kahraman, Sair; Delibalta, M. Suat; Comakli, RamazanNoise affects humans both physically and psychologically, whose impacts vary from person to person. Block cutting machine is one of the most important noise sources in the stone processing plants. This study investigates the predictability of the noise level generated during sawing of carbonate rocks from the P-wave velocity. First, the P-wave velocities of rock samples were measured in the laboratory. Then, the core samples were cut by an automatic cutting machine with diamond saw in the laboratory and noise levels were measured. A strong linear correlation was found between the noise levels and the P-wave velocity. After including the densities of the samples to the analysis, the correlation coefficient was increased significantly. It is concluded that the noise level of carbonate rocks can be estimated using the derived equations from the P-wave velocity. The laboratory noise level can be converted to the site noise level using a conversion factor. © 2019 Proceedings of the International Congress on Acoustics. All rights reserved.Öğe Predicting the noise level in rock sawing from the physico-mechanical and mineralogical properties of rocks(ELSEVIER SCI LTD, 2016) Kahraman, Sair; Delibalta, Mahmut S.; Comakli, Ramazan; Fener, MustafaMillions of employees in the World are exposed to noise at work. Block cutting machine is one of the most important noise sources in the stone processing plants. In this study, the predictability of the noise from the block cutting machines in the stone processing plants was investigated by using the physico-mechanical and mineralogical properties of rocks. The noise levels of some block cutting machines were firstly measured during the cutting of the three different rocks. Then, the core samples of the same rocks were cut by an automatic cutting machine in the laboratory and the noise levels were measured. A conversion factor was obtained by dividing the site noise levels by the laboratory noise levels. Then, nineteen different rocks were cut by the automatic cutting machine in the laboratory and the noise levels were measured. Strong correlations were found between the laboratory noise level and the rock properties. The noise level increases with increasing rock strength, abrasive mineral content, and density. However, increasing porosity decreases the noise level. It was concluded that the laboratory noise level for a new rock type to be cut can be estimated using the derived relations. Then, the laboratory noise level can be converted to the site noise level using the derived conversion factor. (C) 2016 Elsevier Ltd. All rights reserved.Öğe 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, BahtiyarHard 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.
