Yazar "Ozcan, Mustafa" seçeneğine göre listele

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    Evaluation of the behavior of screw pile groups in clay soils under compressive and uplift forces
    (Techno-Press, 2025) Sarici, Talha; Ozcan, Mustafa
    Screw piles, which is one of the ground improvement methods, are finding more place in practice day by day. For this reason, there is a need for studies to investigate the behavior of screw piles under compressive and uplift loads. In this context, the behavior of screw piles with different number of helixes in groups was investigated with different number of screws and group patterns. To evaluate behavior of screw piles, settlement ratios, group efficiency and helix number efficiency values were calculated by using finite element method. Based on an experimental study from the literature, modelling was performed on PLAXIS 3D, which works with the finite element method, and the results were matched. As a result of this study, it was observed that increasing the number of helixes increased the bearing capacity under both compressive and uplift forces. In addition, it was determined that group efficacy values changed in different patterns and different number of pile groups. Optimum screw pile type for group patterns also differs for different load conditions. The modelling results were visualized and were found to match with the failure surfaces reported in the literature. It was suggested that optimum helix number and group pattern for screw pile applications can be achieved with evaluating settlement and efficiency values together.
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    Investigation of Screw Pile Behavior in Cohesive Soil Under Uplift and Compressive Forces by Experimental Studies and Numerical Analyses
    (Springer Heidelberg, 2025) Sarici, Talha; Ozcan, Mustafa
    Within the scope of this study, experimental studies and numerical analyses were carried out to investigate the effect of the use of screw piles and traditional piles without screws on the bearing capacity of cohesive soils under the effect of uplift and compressive forces. In the experimental studies, the effect of changing the number of helixes and the effect of different overburden loads caused by this change were investigated. In numerical analyses, the finite element method was used via Plaxis 3D and a new design different from the commonly used modeling was created using the segmented helix model. After validating the results of numerical analysis and experimental study, the effect of different embedment depths and helix diameters on the behavior of cohesive soil reinforced with screw piles under loads was investigated. According to the results obtained from the study, the bearing capacity of cohesive soil increased as the screw pile helix number increased. Increase in bearing capacity was also observed with increasing embedment depth and helix diameter. In addition, the segmented helix model used in the numerical analyses represented the screw pile behavior more realistically.
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    Investigation of the influence zone of stone columns with and without geogrid encasement by experimental and numerical studies
    (Elsevier, 2025) Demir, Ahmet; Sarici, Talha; Ok, Bahadir; Ozcan, Mustafa
    The influence zone for geogrid encased stone columns (GESC) and ordinary stone columns (OSC) were investigated in the scope of this study. For this purpose, a single stone column (OSC or GESC) was built in clay soil which was placed in tanks had various diameters to observe load-deformation behavior of a 5 cm diameter rigid model footing. The effects of the water content of clay soils on the behavior of stone columns were also investigated. This study consists of two stages. Firstly, experimental studies were conducted at the laboratory using model loading test setup, and secondly, models created with a finite element method (FEM) based software called as Plaxis and numerical analyses were carried. Experimental study results validated the FEM results closely for short-term stability. Therefore, further investigations on FEM models were carried out. As a result of this study, generally, geogrid encasement for the stone columns increased the bearing capacity and the decreased amount of lateral bulging and settlement. In addition, for OSC and GESC, the influence zone was about 5 and 6 times the stone column's diameter, respectively. So, it can be said that encasing the stone column with geogrid reduced the influence zone.
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    Using geopolymer coated and uncoated geotextile as a hybrid method to improve uplift capacity of screw piles in cohesionless soil
    (Elsevier, 2024) Sarici, Talha; Ozcan, Mustafa
    In this research, experimental studies and numerical analyses were carried out to investigate how the usage of geotextile and geopolymer coated geotextile as a hybrid method changes the uplift behavior of the screw piles in cohesionless soil. In this context, traditional pile behavior, the effect of different number of helixes and embedment depths on screw piles, the mechanism of geotextile and the effects of geopolymer coating process were investigated. In addition, experimental studies were modeled by using Plaxis 3D and parametric studies were carried out after verification between the results of experimental study and numerical analysis. In the numerical analysis, a segmented helix model consisting of four 90-degree slices was developed instead of the planar helixes commonly used in the literature. For further investigation of the effectiveness of hybrid method, parameters such as improvement ratios and breakout factors were calculated. When the results obtained within the scope of the study were evaluated, the geopolymer coating process increased the bearing capacity of the geotextile by 24 % at 27 % less elongation. It was also seen that uncoated and geopolymer coated geotextile increased the screw pile performance in terms of improvement ratios by 294 % and 364 %, respectively.