WoS İndeksli Yayınlar Koleksiyonu
Permanent URI for this collectionhttps://hdl.handle.net/20.500.12573/394
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Article Integrated Quantitative Modelling for the Dimension Stone Quality Evaluation: Implications for Sustainable Resource Management(Springer Heidelberg, 2025-09-30) Koken, Ekin; Strzalkowski, Pawel; Strzałkowski, PawełThe growing demand for dimensional stones in construction and monument conservation requires fast, repeatable and scientifically valid quality assessment procedures. The present study, in this context, established a solid foundation for quantifying the quality of dimension stones by adopting two quantitative methods: the Suitability Index (SI) and Dimension Stone Field Performance Coefficient (DSFPC). Both methods were coded in the MATLAB environment and implemented for 20 different rock types used in various dimension stone applications in Turkey. Evaluations based on the above-mentioned methods demonstrate that the DSFPC provides a more conservative assessment than the SI method. Additionally, engineering interpretations derived from the SI and DSFPC approaches are compared with recently published classification systems developed for the dimension stone industry. Focusing on this comparison, it is concluded that the adopted methods offer a more holistic evaluation framework compared to the approaches based solely on a single input parameter, such as effective porosity (ne), uniaxial compressive strength (UCS), or B & ouml;hme abrasion value (BAV) of rocks. Furthermore, it is concluded that the adopted methods complement each other by yielding supportive outcomes. The coded methods can be adapted to other lithological series and integrated with spatial information systems to support decision-making in mining and construction sectors. From this point of view, the present study may be considered a case study supporting holistic approaches to sustainable resource management in the dimension stone industry.Article Citation - WoS: 5Citation - Scopus: 5Investigations on Fracture Evolution of Coal Measure Sandstones from Mineralogical and Textural Points of View(Springer India, 2020-04-09) Koken, EkinThe purpose of the present study is to investigate the variations in fracture evolution of sandstones arising from mineralogical and textural features. For this purpose, eight types of coal measure sandstones located in the Zonguldak Hardcoal Basin (ZHB) were considered. The mineralogical and textural characterizations of the rocks were carried out. Physico-mechanical properties were determined for each rock type. Based on quantitative strain-based methods, the crack initiation (sigma(ci)) and crack damage (sigma(cd)) thresholds of the sandstones were determined. The laboratory test results indicate that the sigma(ci)and sigma(cd)of the sandstones were found to be between 0.27-0.43 and 0.61-0.83 of the UCS, respectively. In general, the sigma(ci)and sigma(cd)correspond to 0.37 and 0.71 of the UCS, respectively. The sigma(ci)and sigma(cd)decrease with increasing the sorting coefficient (S-c), average grain size (d(50), mm), contents of feldspar (F, %), and lithic fragment (LF, %). On the other hand, increasing quartz content (Qtz, %) increases those variables. Remarkable changes were obtained in the sigma(ci)and sigma(cd)when effective porosity (n(e)) and pulse wave velocity (V-p) of the rocks exceed 3% and 3.00 km/s, respectively. As a result of mineralogical analyses and laboratory studies, statistical analyses were carried out. Accordingly, the sigma(ci)and sigma(cd)could be estimated reliably using several empirical relationships established in the present study. In order to represent the importance and utilization of rock mineralogy and texture for underground mining applications in the ZHB, several suggestions and considerations related to aV-cut gallery blasting operation were introduced.Article Geological-Geochemical Signatures of Opal Occurrences in Keciborlu (Isparta-Turkey)(Pamukkale Univ, 2022) Baspinar Tuncay, Ebru; Koken, Ekin; Kuscu, Mustafa; Cengiz, Oya; Aydemir, Fatih; Raimov, Rahmen; Tuncay, Ebru BaspınarSilica-rich solutions, considered as the final products of acidic volcanism, which started from the Late Miocene to throughout the Plio-Quaternary around Isparta, are effective along the main fault observed around the Keciborlu (Isparta) sulfur deposit. Therefore, opal occurrences are intensively observed along this fault zone. Opal occurrences are in various colors such as gray, beige, yellowish, reddish, blackish. Opals with a massive structure, observed as bands, are sharp -edged, conchoidal diffraction, translucent, matte, oily glossy surface opals are iron oxidized. Some opals contain brecciated rock fragments. The locations of the opal occurrences in the field were determined in this study. Using representative samples, structural and textural properties of opals were determined by thin section, scanning electron microscopy analyses, and mineral paragenesis was analyzed via x-ray diffraction and Fourier transform infrared spectroscopy analyses. Geochemical findings revealed chemical compositions. Based on the thin-section studies, it was observed that the opalized samples lost their primary properties due to the effect of hydrothermal solutions and they became iron oxidized, laminated, and argillized. In addition, they contain opaque minerals such as magnetite and hematite. Different micro textures such as amorphous, granular, desert rose, and lepisphere quartz associations were observed in SEM images. In the XRD and FTIR analyzes, it was determined that most of the opals were Opal CT and some of them were defined as Opal C type. Based on the geochemical analyses considering Ba <120 ppm and Ca >200 ppm, the remarkable changes in loss on ignition values, and the relative relationship between C/T ratio and Ga, such hydrothermal alterations in opals the Keciborlu opals were found to have the magmatic origin.Article Citation - WoS: 5Citation - Scopus: 5Evaluation of Soft Computing Methods for Estimating Tangential Young Modulus of Intact Rock Based on Statistical Performance Indices(Springer, 2022-04-06) Koken, Ekin; Kadakci Koca, TumayThe tangential Young modulus (E-ti) of intact rock is a critical parameter in engineering geological design calculations and rock mass classification systems. The E-ti of various rock types has been successfully estimated by many studies based on numerous soft computing methods in recent years. However, these studies mainly involve a single analysis method or are valid for a limited number of samples. For this reason, this study aimed to compare artificial neural networks (ANN), adaptive neural fuzzy inference system (ANFIS), and Gene expression programming (GEP) methods to estimate the E-ti of various rock types based on 147 datasets collected from the published literature. As a result of the soft computing analyses, three different predictive models were proposed in this study. In the proposed prediction models, rock properties such as dry density (rho(d)), effective porosity (n(e)), P-wave velocity (V-p), and uniaxial compressive strength (UCS) were used. The estimation performance of the proposed models was examined through several performance indices such as coefficient of determination (R-2), root mean square error (RMSE), the variance accounted for (VAF), and mean absolute percent error (MAPE). As a result of statistical analyses, it was determined that the ANFIS model presents a better prediction performance (R-2 = 0.967) than the other methods in the training datasets. On the other hand, the accuracy of the ANFIS model decreased significantly in the test datasets (R-2 = 0.803). Furthermore, the GEP model presented the lowest predictive performance. Finally, considering the overall estimation accuracy of the proposed models, it was concluded that the proposed ANN model with an R-2 of 0.94 could reliably be used to estimate the E-ti of investigated rocks.Article Citation - WoS: 1Citation - Scopus: 2Estimating Uniaxial Compressive Strength of Pyroclastic Rocks Using Soft Computing Techniques(Shahrood Univ Technology, 2024) Koken, EkinIn this study, several soft computing analyses are performed to build some predictive models to estimate the uniaxial compressive strength (UCS) of the pyroclastic rocks from central Anatolia, Turkey. For this purpose, a series of laboratory studies are conducted to reveal physico-mechanical rock properties such as dry density (rho d), effective porosity (ne), pulse wave velocity (Vp), and UCS. In soft computing analyses, rho d, ne, and Vp are adopted as the input parameters since they are practical and cost-effective non-destructive rock properties. As a result of the soft computing analyses based on the classification and regression trees (CART), multiple adaptive regression spline (MARS), adaptive neuro-fuzzy inference system (ANFIS), artificial neural networks (ANN), and gene expression programming (GEP), five robust predictive models are proposed in this study. The performance of the proposed predictive models is evaluated by some statistical indicators, and it is found that the correlation of determination (R2) value for the models varies between 0.82 - 0.88. Based on these statistical indicators, the proposed predictive models can be reliably used to estimate the UCS of the pyroclastic rocks.Article Citation - WoS: 8Citation - Scopus: 12Assessment of Rock Aggregate Quality Through the Analytic Hierarchy Process (AHP)(Springer, 2020-05-22) Koken, Ekin; Top, Soner; Ozarslan, AhmetThe present study aimed to assess rock aggregate quality through the Analytic Hierarchy Process (AHP). In the context of the AHP analyses, four rock types (i.e., andesite, basalt, granodiorite, and gabbro), five evaluation criteria, and several technical requirements/suggestions for coarse aggregates related to bituminous paving mixtures were considered. In order to set over the evaluation criteria, detailed laboratory studies were conducted. For this purpose, various mineralogical, physical, and mechanical aggregate properties were determined for each rock type concerning their weathering grades. As a result of the laboratory studies, it was determined that the rock weathering processes have substantial negative impacts on the rock aggregate properties considered in this study. The AHP analysis results indicated that that different rock types have several advantages concerning various evaluation criteria. Based on the general evaluation point (EP) of the rocks, the gabbros were found to have the highest rock aggregate quality (EP = 0.393). In contrast, the andesites had the lowest quality (EP = 0.069). Besides, the basalts (EP = 0.271) and granodiorites (EP = 0.267) presented approximately the same quality for their use in bituminous pavement mixtures. It was also demonstrated that the AHP, with its specific methodology, can be utilized to represent different environmental and mechanical conditions by changing the relative weight of the evaluation criteria. In this way, the pros and cons of different rock types could be revealed quantitatively, which enables related engineers to select proper rock types for their use under different environmental and mechanical conditions. From this point of view, the present study could be declared a case study noted for combining theoretical and practical approaches on bituminous paving mixtures as a sign of rock aggregate quality.Article Citation - WoS: 2Citation - Scopus: 3Assessment of Rock Aggregate Quality Through Fuzzy Inference System(Springer, 2022-04-01) Koken, Ekin; Baspinar Tuncay, EbruIn this study, Fuzzy Inference System (FIS) was adopted to evaluate the rock aggregate quality. For this purpose, some technical standards for coarse aggregates were integrated into the FIS analyses as threshold values. As a result, several membership functions were established using rock aggregate properties such as water absorption by weight (w(a)), flakiness index (FI), Los Angeles abrasion value (LAAV), and magnesium sulfate soundness (M-wl). Based on 48 if-then rules, the implementation and verification of the proposed FIS model were carried out using sixteen rock types whose field performances as coarse aggregate were previously evaluated [i.e., low quality (LQ), average quality (NQ), high quality (HQ), etc.] by field engineers. The results obtained from the FIS analyses were declared a Rock Aggregate Quality Assessment Rating (RQAR), where higher RQAR values indicate rock aggregates with higher quality. The results obtained from the FIS analyses are almost in good agreement with those obtained from the field performances of the investigated rocks. However, the number of cases should be increased to improve the proposed FIS model. In this context, the number of if-then rules membership functions can be rearranged according to the need. This study, in this manner, can be declared a case study indicating how to quantity rock aggregate quality based on FIS analyses.Article Citation - WoS: 6Citation - Scopus: 7Assessment of Los Angeles Abrasion Value (LAAV) and Magnesium Sulphate Soundness (MWL) of Rock Aggregates Using Gene Expression Programming and Artificial Neural Networks(Polska Akad Nauk, Polish Acad Sciences, 2023-07-24) Koken, EkinIt has been acknowledged that two important rock aggregate properties are the Los Angeles abrasion value (LAAV) and magnesium sulphate soundness (Mwl). However, the determination of these properties is relatively challenging due to special sampling requirements and tedious testing procedures. In this stu-dy, detailed laboratory studies were carried out to predict the LAAV and Mwl for 25 different rock types located in NW Turkey. For this purpose, mineralogical, physical, mechanical, and aggregate properties were determined for each rock type. Strong predictive models were established based on gene expression programming (GEP) and artificial neural network (ANN) methodologies. The performance of the proposed models was evaluated using several statistical indicators, and the statistical analysis results demonstra-ted that the ANN-based proposed models with the correlation of determination (R2) value greater than 0.98 outperformed the other predictive models established in this study. Hence, the ANN-based predictive models can reliably be used to predict the LAAV and Mwl for the investigated rock types. In addition, the suitability of the investigated rock types for use in bituminous paving mixtures was also evaluated based on the ASTM D692/D692M standard. Accordingly, most of the investigated rock types can be used in bituminous paving mixtures. In conclusion, it can be claimed that the proposed predictive models with their explicit mathematical formulations are believed to save time and provide practical knowledge for evaluating the suitability of the rock aggregates in pavement engineering design studies in NW Turkey.Article Citation - WoS: 10Citation - Scopus: 9Assessment of Deformation Properties of CoAl Measure Sandstones Through Regression Analyses and Artificial Neural Networks(Polska Akad Nauk, Polish Acad Sciences, 2023-07-24) Koken, EkinThe deformation properties of rocks play a crucial role in handling most geomechanical problems. However, the determination of these properties in laboratory is costly and necessitates special equipment. Therefore, many attempts were made to estimate these properties using different techniques. In this study, various statistical and soft computing methods were employed to predict the tangential Young Modulus (Eti, GPa) and tangential Poisson's Ratio (vti) of coal measure sandstones located in Zonguldak Hardcoal Basin (ZHB), NW Turkey. Predictive models were established based on various regression and artificial neural network (ANN) analyses, including physicomechanical, mineralogical, and textural properties of rocks. The analysis results showed that the mineralogical features such as the contents of quartz (Q, %) and lithic fragment (LF, %) and the textural features (i.e., average grain size, d50, and sorting coefficient, Sc) have remarkable impacts on deformation properties of the investigated sandstones. By comparison with these features, the mineralogical effects seem to be more effective in predicting the Eti and vti. The performance of the established models was assessed using several statistical indicators. The predicted results from the proposed models were compared to one another. It was concluded that the empirical models based on the ANN were found to be the most convenient tools for evaluating the deformational properties of the investigated sandstones.