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    GIS-based landslide susceptibility mapping using AHP, FMEA, and Pareto systematic analysis in central Yalova, Türkiye
    (Elsevier - Division Reed Elsevier India Pvt Ltd, 2025) Demirel, Burak; Yildirim, Eray; Can, Eray
    Yalova is a region with high landslide risk due to its climate, terrain, geographical features, and geological structure. Landslides in the region are of critical importance to produce landslide susceptibility maps and risk management because of the material and moral damage they cause. This study aimed to produce a Geographic Information System (GIS)-based landslide susceptibility map (LSM) of the Yalova central region using the Analytic Hierarchy Process (AHP), Failure Mode and Effect Analysis (FMEA), and Pareto systematic analyses. Lithology, slope, aspect, distance from roads, NDVI (Normalized Difference Vegetation Index), distance from faults, land use, rainfall, distance from rivers, and elevation factors were used in the analyses. The FMEA, Pareto, and AHP methods were used in an integrated and sequential manner to determine the LCF weights. According to the analysis, lithology was identified as the most influential factor, with the highest weight at 29.5%, while appearance had the lowest weight at 1.5%. The LSM was generated by processing the weight values in the prepared LCFs. Based on the produced landslide susceptibility map, the study area was categorized as having 29.60% very low-risk, 29.51% low-risk, 24.04% moderate-risk, 13.18% high-risk, and 3.68% very high-risk. Regional planning should be undertaken according to the landslide risk categories, and appropriate measures should be determined for each level in advance. Upon comparing the produced LSM with the existing inventory, it was determined that 95.29% of the previously occurring landslides in the region were in risky areas on the LSM. The results demonstrate the integrated applicability of the AHP, FMEA, and Pareto methods and provide a more accurate weighting of LCFs compared to a single method. The approach used in this study can be easily adapted to different regions and can be used not only for landslide analysis but also for risk assessment studies in other disciplines.
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    Improved Engineering Properties of SWC and OPC-Treated HPC Soil
    (Springer Science and Business Media Deutschland GmbH, 2025) Mollamahmutog?lu, Murat; Avci, Eyübhan; Yildirim, Eray; Deveci, Emre; Uysal, Melih
    In this research, it was aimed to treat high plasticity clayey (HPC) soil with super white cement (SWC). To determine the effectiveness of SWC in the stabilization of HPC soil, ordinary Portland cement (OPC) was also used in the experimental studies for the purpose of comparison. As the unconfined compressive strength (UCS) values of SWC-treated HPC specimens dried in open air showed an increase of 390%, the UCS values of wet-cured specimens showed a 235% increase. In addition, while the UCS values of OPC-treated HPC specimens dried in open air displayed an increase of 235%, the UCS values of wet-cured specimens displayed a 130% increase. Both stabilizers were also effective in reducing the swelling pressure and the swelling percentage of HPC soil. The swelling pressure and percentage of HPC soil treated with OPC were reduced by 50 and 90% respectively. As the compressibility of HPC soil stabilized with SWC was reduced by 95%, the compressibility of HPC soil stabilized with OPC was reduced by 88%. The UCS, swelling and compressibility tests have shown that New type cement of SWC is a more effective material than OPC in improving the engineering properties of HPC. © The Author(s), under exclusive licence to Shiraz University 2025.
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    Investigation of changes in the Frequency Content of the Ultrasonic Pulse Waves Propagating through Stabilized Soils
    (Elsevier, 2025) Bas, Deniz; Yildirim, Eray
    This study investigated the changes in the frequency content of ultrasonic waves propagating through stabilized soils under different curing conditions and durations. Additionally, the relationship between the observed frequency changes and the results of soil stabilization was explored. S,ile, Ukrainian, and Pazaryeri clays and organic soil were used, with calcium aluminate cement (CAC) used as a binder. Unconfined compressive strength (UCS) and UPV tests were performed on untreated and stabilized soils under immediately, air-cured, and wet-cured conditions. During the UPV tests, numerical data were obtained by recording the measurement waveforms in the time domain using an oscilloscope. The relationships among the UCS, UPV, arrival times, and spectral amplitudes were examined through regression analysis, yielding significantly high coefficients of determination. The amplitude spectra were obtained by performing a Fourier transform of the waveforms. Significant changes were observed in the amplitude spectra of the untreated and stabilized samples. Untreated soils exhibited heightened attenuation at higher frequencies compared with stabilized soils. All samples exhibited distinct amplitude spectra. The samples with higher UCS exhibited higher amplitudes and predominant frequencies. In organic soils with the lowest UCS, higher frequencies were attenuated, and lower frequencies predominated. In addition, the amplitudes decreased in the frequency domain. These findings highlight the effect of soil stabilization and performance on frequency content.
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    Reconnaissance report on damage caused by the February 6, 2023, Kahramanmaras, Earthquakes in reinforced-concrete structures
    (Elsevier, 2024) Sezgin, Sedef Kocakaplan; Sakcali, Gokhan Baris; Ozen, Sueleyman; Yildirim, Eray; Avci, Eyuebhan; Bayhan, Beyhan; Caglar, Naci
    Two destructive earthquakes occurred in Kahramanmaras, on February 6th, 2023, with magnitudes of Mw = 7.7 and Mw = 7.6, respectively, causing loss of lives and economic loses. A field investigation was carried out in the affected area between February 12th and 26th, 2023, and the findings are detailed in this paper focusing on the damages and causes of failures in reinforced concrete (RC) structures, both in terms of structural and non-structural elements. The seismic history, characteristics of earthquakes, and an assessment of strong ground motion results are also summarized. Recommendations are provided to mitigate future earthquake-induced damages and save lives.
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    Stabilization of Clayey Soil with Alkali-activated Hybrid Slag/Cement
    (Budapest University of Technology and Economics, 2024) Yildirim, Eray; Bol, Ertan; Avci, Eyübhan; Özocak, Aşkin
    This study investigates the stabilization performance of clayey soil treated with alkali-activated hybrid slag/cement. Sodium silicate (SS) and sodium hydroxide (SH) are used as alkali activators, whereas ground blast furnace slag (GGBS) and ordinary Portland cement (OPC) are used as sources of aluminosilicate. A total of 27 different types of mixtures are used for stabilization. Unconfined compressive strength (UCS) of untreated clay and stabilized soils are performed at immediately, 3-, 7-, 28-, and 90 days curing times under air-dried and wet-cured conditions. In addition, 90-d volume and mass changes in the samples are measured. Stabilized samples with an SS/SH ratio of 1 under air-dried conditions reveal moistening at early curing ages (?28 days); afterward, sodium carbonate crystals appear in these samples at longer curing ages. Geopolymer-treated clayey soil exhibits lower volumetric and mass changes compared with OPC. Most of the stabilized clayey soil with alkali-activated hybrid slag/cement exhibits higher strength compared with OPC under air-dried and wet-cured conditions. © 2024, Budapest University of Technology and Economics. All rights reserved.