Person: MERT, AHMET CAN
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MERT
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AHMET CAN
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Publication Metadata only The Spatial Distribution of Liquefaction Susceptibility by Logistic Regression Model Adapted for Adapazari, Turkey(2020) MERT, AHMET CAN; AREL, ERSİN; ÖNALP, AKIN; 258088; 136055; 2172A logistic regression model has been developed for evaluation of soil liquefaction by the use of cone penetration test (CPTu, PCPT) on data collected from Adapazari, Turkey. The model inputs are the clean sand equivalent normalized cone tip resistance (q(c1N,cs)) and cyclic stress ratio corrected for moment magnitude of 7.5 earthquake (CSRM=7.5) that was experienced in 1999. Liquefaction probabilities (P-L) are obtained for each district of the city for which CPTu data is available with the proposed logistic regression model. Average liquefaction probabilities of the depth interval 0-6 m and coordinates (Longitude, Latitude) of CPT soundings were plotted to construct a liquefaction probability map by longitude and latitude. In order to show the effect of depth in liquefaction potential, the obtained liquefaction probability contours were reconstructed by dividing 0-6m depth into three narrow sublayers of 0-2m, 2-4m and 4-6m wherein liquefaction was observed during the earthquake. For each depth interval, liquefaction probabilities of the districts are compared with the observed liquefied and non-liquefied sites in the city after 1999 Adapazari Earthquake.Publication Open Access Calculation of Pile Capacity in Cohesionless Soil by CPT Considering Spatial Variability(Çukurova Üniversitesi Mühendislik Fakültesi, 2021) MERT, AHMET CAN; YAZICI, GÖKHANThe study aims to construct a framework for CPT based ultimate pile capacity calculation for cohesionless soils with random field theory. Cone tip resistance (qc) was taken as the spatially varying parameter with a constant mean and changing coefficients of variation. CPT profiles were simulated with random field generations, and the ultimate capacity of a single pile (Qu) was calculated with these simulations. The influence of spatial variation of qc on the variation of Qu was investigated. The proposed framework was finally verified by comparing the results of an actual CPT database and the simulated CPT profiles in the study. The results showed that the critical vertical scale of fluctuation for CPT-based pile capacity calculations was equal to one diameter of pile (dv=1D), and that the method effectively predicted the ultimate pile capacity through simulated CPT profiles with random field. The proposed method is especially recommended for cases where the uncertainty consideration is necessary, yet the site-specific data is limited. The study aims to contribute a simple framework to the methods of CPTbased pile capacity with unceratinty consideration. The propesed method aims to facilitate the pile design framework with limited available data.Publication Open Access Analysis of a Prefabricated Vertical Drain (PVD) Soil Improvement Project(Turkish Chamber Civil Engineers, 2022) MERT, AHMET CAN; AREL, ERSİN; ÖNALP, AKINA settlement analysis has been carried out for several sectors of a rail station yard improved with prefabricated vertical drains (PVD) in Istanbul, that exhibited prolonged consolidation beyond the predicted values in certain sectors of the treated zone. Final settlement and End of Primary (EOP) settlement times have been estimated theoretically as well as using the Asaoka graphical procedure. The compliance of settlement-time curves with in-situ measurements and Asaoka solution has been investigated. A geotechnical model was developed for finite element and three-dimensional consolidation analyses. The settlement curves obtained by varying horizontal-vertical permeability coefficient ratio (k(h)/k(v)) and in-situ measurements have been compared, and k(h)/k(v) values corresponding to 90% degree of consolidation has been computed for all sectors. The effect of drain spacing (S-drain) as well as drain length (L-drain) on the rate of consolidation have been evaluated for each sector, keeping the specified ratios constant. The times corresponding to 95% degree of consolidation (t(95)) have been calculated using the theoretical solution and compared to in-situ measurements. Calculated t(95)'s has also been compared to their estimated values by varying the spacing (S-drain) and the length (L-drain). Additionally, the required intervals of S-drain and L-drain have been obtained corresponding to the calculated t(95) times. The analyses suggest that the main reason for prolonged consolidation was the horizontal to vertical permeability coefficient ratio. According to the analysis results, PVD implementation was not efficient in clays having k(h)/k(v) of approximately unity. The main conclusion of this study was to discover the necessity for optimizing the variables in any such project. The efficacy of the works can be significantly enhanced if simultaneous evaluation of the parameters S-drain and L-drain and the permeability ratio k(h)/k(v) is carried out prior to field work. Otherwise, "accidents" may emerge as found out in this project.Publication Restricted Field Simulation of Settlement Analysis for Shallow Foundation Using Cone Penetration Data(Elsevier Science Ltd., 2021) MERT, AHMET CAN; AREL, ERSİNThis paper deals with the settlement analysis of a vertically loaded strip footing by the use of two-dimensional random field finite element method. Total settlement and rotation of the footing have been calculated by elasto-plastic solution in finite element model. Deformation modulus of soil E-d was assigned conforming to 2D Gaussian random field using Karhunen-Loeve series expansion. Spatial variability of E-d was represented by the horizontal and vertical correlation lengths (theta(vE) and theta(hE)). CPTu database from Adapazari, Turkey has been employed to estimate the correlation lengths. Soil profile was modelled with 4 layers in accordance with random field from in-situ test results, and correlation lengths were assigned to each different layer. Random field realizations were produced by MATLAB code, and probability density functions (PDF) of maximum total settlement and rotation of the footing were constructed using Monte Carlo Simulations by iterative solutions of each realization with finite element analysis. Probabilities of failure (P-f) by settlement and rotation were calculated from PDFs. Initially, the analysis was carried out using average values of each horizontal and vertical correlation lengths that were assigned to every soil layer. Subsequently, analyses were iterated with maximum and minimum values of the correlation lengths in order that both the effect of horizontal and vertical spatial variability can be considered. 1000 calculations were performed for the 5 analysis models, with 200 random field realizations for each model. The effect of varying theta(vE) and theta(hE) on total settlement and rotation of the footing has also been investigated.