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Öğe EFFECTS OF THE COVID-19 PANDEMIC ON TURKISH NATURAL STONE INDUSTRY: A GREY FORECASTING MODEL(2022) Ekincioğlu, Gökhan; Akbay, Deniz; Aydemir, ErdalWhen the indicators in recent years are examined in the developing and renewed economic environment in Turkey, it is seen that the momentum of the natural stone industry and its share in total mining exports have increased steadily. However, the Covid-19 pandemic in 2020, which affected the whole world, also affected the Turkish natural industry. Within the scope of this study, the export values of the Turkish natural stone industry on a monthly and yearly basis were evaluated both before the pandemic and during the pandemic. Export figures for 2020 and 2021 were tried to be estimated using the Gray Forecast model. With the effect of the Covid-19 pandemic, natural stone export figures for 2020 fell behind 2019 in February, March, April and May. With the normalization process in June, July and Months, normalization started in export figures and exceeded the export values of 2019 in September, October, November and December. In 2020, which was entered with great hopes, it was not possible to reach the targeted figures this year due to the pandemic. In addition, Also, export values for 2020 and 2021 were predicted using a GM (1,1) grey forecasting model, which is a method frequently used in uncertainty cases. 2020 and 2021 export values were estimated by using the GM (1,1) gray forecasting model, which is a method frequently used in uncertainty situations. It has been seen that the model can be used reliably to predict natural stone export figures. In the following years, some assessments and recommendations have been made that may make the Turkish natural stone industry stronger in the following years on issues such as health management of crises and adaptation to the current situation if such outbreaks are replicated in the global world economy.Öğe Estimating Uniaxial Compressive Strength of Sedimentary Rocks with Leeb Hardness Using Support Vector Machine Regression Analysis and Artificial Neural Networks(Gazi Univ, 2024) Ekincioğlu, Gökhan; Akbay, Deniz; Keser, SerkanUniaxial compressive strength (UCS) of rock materials is a rock property that should be determined for the design and stability of structures before underground and aboveground engineering projects. However, it is impossible to determine the properties of rocks such as UCS directly due to the lack of standardized sample preparation, necessary equipment, etc. In this case, the UCS of rocks is predicted by index test methods such as hardness, ultrasound velocity, etc. Determining the hardness of rocks is relatively more practical, fast, and inexpensive than other properties. In this study, the UCS of sedimentary rocks was predicted as a function of Leeb hardness using artificial neural network (ANN) and Support Vector Machine (SVM) regression analysis. With the proposed ANN and SVM regression models, it is aimed to obtain more accurate and faster prediction values. To better train the models created in the study, the number of data was increased by compiling data from the studies in the literature. The UCS values predicted by the models obtained with two different methods and the measured UCS values were statistically compared. It was proved that the models created with ANN and SVM regression can be used reliably in predicting UCS values.Öğe Farklı cihaz ve yöntemler ile belirlenen Shore sertlik değerlerinin karbonatlı kayaçların gevreklik değerlerinin tahmininde kullanılabilirliğinin incelenmesi(Pamukkale Üniversitesi, 2021) Akbay, Deniz; Ekincioğlu, Gökhan; Altindağ, Raşit; Şengün, NazmiYeraltı veya yer üstü mühendislik projeleri öncesinde kayaçların kesilebilirlik ve delinebilirlik özelliklerini etkileyen sertlik ve gevreklik değerlerinin belirlenmesi çok önemlidir. Kayaçların kesilebilirlik ve delinebilirlik özelliklerini belirlemek, bazı diğer fiziksel ve mekanik özelliklerini doğrudan belirlemek için uygulanan testler gibi pahalı ve zaman alıcı olabilmektedir. Kayaçların sertlik değerlerinin belirlemesi nispeten diğer özelliklerine göre daha ekonomik ve hızlı olmaktadır. Ayrıca sertlik değerleri, kayaçların fiziksel ve mekanik özelliklerinin tahmininde güvenilir bir şekilde kullanılabilmektedir. Bu çalışma kapsamında, 13 farklı karbonatlı kayacın Shore sertlik değerleri üç farklı cihaz (C-2 tipi Shore Scleroscope’u, dijital durometre ve dijital Shore sertliği ölçüm cihazı) kullanılarak aynı numuneler üzerinde belirlenmiştir. Elde edilen veriler sonucunda farklı ölçüm cihazlarının klasik yöntem yerine kullanılabilirliği araştırılmıştır. Ayrıca kazı mekaniği açısından önemli bir kayaç özelliği olan ve literatürde basınç ve çekme dayanımı değerleri dikkate alınarak önerilen dört farklı gevreklik değerinin tahmin edilmesinde kullanılabilecek en uygun yüzey sertliği ölçme yönteminin belirlenmesi amaçlanmıştır. Üç farklı cihazdan elde edilen Shore sertlik değerleriyle dört farklı gevreklik değeri arasındaki ilişkiler basit regresyon analizleri ile irdelenmiştir. Sonuç olarak dijital Shore sertliği ölçüm cihazlarının klasik C-2 tipi Shore Scleroscope’u yerine güvenli bir şekilde kullanılabileceği görülmüştür. Shore sertlik değerinin literatürde çokça kullanılan dört farklı gevreklik değerinden iki tanesini tahmin etmede güvenilir olduğu iki tanesini tahmin etmede ise kullanılamayacağı belirlenmiştirÖğe SUGGESTING CONVERSION FACTOR COEFFICIENTS for ESTIMATING DIFFERENT TYPES of SCHMIDT HAMMER REBOUND HARDNESS VALUES(2023) Akbay, Deniz; Ekincioğlu, GökhanMechanical properties of rocks such as uniaxial compressive strength, tensile strength, shear strength are the properties that determine their behavior under load. These properties of rocks are often determined by difficult, complex, time-consuming and expensive test methods. Therefore, instead of determining these properties directly, these properties can be estimated indirectly by using relatively inexpensive, fast and easily applicable methods. The surface hardness parameter of Schmidt hammer rebound hardness is fast, inexpensive, and easy to apply to determine the hardness of rocks and concrete. It is also used to indirectly determine the mechanical properties of rocks. It is seen that two different types of hammers (N-type and L-type) with different impact energies are commonly used in the literature. In this study the correlations between the surface hardness of different rocks obtained using N-type and L-type Schmidt hammers were analyzed. For this purpose, data were compiled from studies in the literature, which included both N-type and L-type Schmidt hammer rebound hardness of different rock types, and the collected data were analyzed statistically. Coefficients have been proposed for the conversion of N-type and L-type Schmidt hammer rebound hardness to each other.Öğe THE EFFECT OF SAMPLE SIZE ON THE FLEXURAL STRENGTH OF SEDİMENTARY CARBONATE ROCKS UNDER CONCENTRATED LOAD(2021) Akbay, Deniz; Şengün, Nazmi; Altındağ, Raşit; Ekincioğlu, GökhanFlexural strength is an important mechanical property used in the selection of the application area of natural building stones. The flexural strength of natural stones in our country is determined according to the test standards prepared by the European Union. According to TS EN 12372, the recommended test sample dimensions for the determination of the flexural strength of natural stones are 50×50×300 mm. However, generally, 20-30 mm thick plates are used in flooring, cladding, and exterior applications in buildings. In practice, 50 mm thick plates are rarely used, as well as preparing 50 mm thick test samples is a laborious and time-consuming process. In this study, it has been investigated how much the sample size affects the flexural strength of sedimentary carbonate rocks when using test samples prepared in two different sizes. It has been observed that the flexural strength values obtained from the test samples prepared in different sizes of the same rock are very close to each other. Besides, the stress distributions formed on the rock sample were analyzed with ANSYS Workbench 2020 R1. It has been determined that the stress distributions in the samples prepared in different sizes, exposed to the same load, occur in the same regions, and concentrate.Öğe Usability of Digital Shore Hardness Devices in Estimation of Physical and Mechanical Properties of Rocks(Springer, 2021) Akbay, Deniz; Ekincioğlu, GökhanIn this study, the Shore hardness measurements are made on carbonate rocks using Durometer PCE-1000, Mitech MH310 Hardness Tester and C-2 type Shore Scleroscope, and the results obtained were compared. The usability of digital new generation Shore hardness test devices (Durometer PCE-1000 and Mitech MH310 Hardness Tester) to determine the Shore hardness of the rocks is investigated.
