Browsing by Author "Yenginar, Yavuz"

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A Case Study: Cost-Benefit and Risk Analyses of Gabion Wall for Rockfall Protection Method in Bozkir, Turkey
(Konya Teknik Univ, 2024) Fidan, Bekir; Yenginar, Yavuz; Olgun, Murat
The construction of residential buildings, highways, and dams in the areas under the risk of rockfall constitutes a significant threat to life and property safety. Previously, the easiest solution for rockfall protection was to move the settlements in the regions under rockfall risk to another location although it was expensive. Another method is removing the rocks by hand, machine, or using explosives, since it is dangerous. Nowadays, various rock improvement methods of constructing barriers exist due to the developing technology and facilities. In the study, to resist the rockfall, a case study on analysis of a gabion wall in the Derek & ouml;y neighborhood of Bozk & imath;r District in Konya was presented. In the preliminary design stage, mapping studies, rock kinematic analyses, and the possible rockfall scenarios in the study area were carried out to determine the current conditions of the land before the construction works. The rockfall analysis shows that the rocks on the slope will reveal energy of 400-500 kJ, and the splash heights may vary between 30-150 cm. As a result of this data, a 420m-length and 3m-height gabion wall was constructed. The gabion wall, which has a 10000-kJ energy damping capacity, eliminates the risk of rockfall for 150 houses in the region. A huge cost-benefit has been achieved by constructing a gabion wall instead of other methods (expropriation of 150 houses or the surface coating with steel mesh) as a precaution against the hazard of rockfall in the study area.
Derin Karıştırma Kolonlarının Performansını Etkileyen Faktörlerin Model Deneylerle Araştırılması
(Konya Teknik Üniversitesi, 2020) Yenginar, Yavuz; Olgun, Murat
Bu tez çalışması ile killi bir zeminde imal edilen uçucu kül katkılı derin karıştırma kolonlarının (DKK) performansını etkileyen parametreler araştırılmıştır. Deneysel çalışmalar, derin karıştırma makinesiyle imal edilen kolonlar (büyük ölçekli DKK) ve mikserle hazırlanan zemin-enjeksiyon karışımları (küçük ölçekli DKK) üzerinde yürütülmüştür. Deneysel çalışmaların tasarımı Taguchi yöntemi kullanılarak yapılmıştır. Her bir araştırma alanında ve ilgili kür süreleri sonunda DKK'nın performans değerleri belirlenerek elde edilen sonuçlar S/N ve çok değişkenli varyans analizleri (ANOVA) ile değerlendirilmiş, regresyon analizleri ile matematiksel modeller kurulmuş, sonrasında optimizasyon çalışmaları yürütülmüştür. Büyük ölçekli DKK imalatlarının yapılabilmesi için öncesinde homojen ve sürekli DKK oluşumu için gerekli imalat parametreleri araştırılmıştır. Optimum imalat parametreleri olarak; çimento dozajı 325 kg/m3, karıştırma bıçaklarının dönme hızı 80 devir/dk, enjeksiyon deliklerinin çapı 3 mm ve zeminin likitlik indisi 1 şeklinde belirlenmiştir. Uçucu kül katkılı DKK tasarımlarında 7, 28 ve 56 gün kür süreleri sonunda DKK'nın serbest basınç (qu) ve üç eksenli basınç dayanımları (quu), zemin iyileştirme derecesi (RI), sıkışma indisi (Cc) ve permeabilite katsayısı (k) değerleri belirlenmiştir. DKK performansının en iyi olduğu durum için optimum imalat parametreleri; bağlayıcı dozajı 425 kg/m3, uçucu kül oranı %40, süper akışkanlaştırıcı katkı oranı %3, su/bağlayıcı oranı 0.8 ve zeminin likitlik indisi 1 olarak belirlenmiştir. DKK uygulamalarında %40 uçucu kül kullanılması ile çimento kullanımı ve enjeksiyon maliyeti %40 oranında azalmış olacaktır. Küçük ölçekli DKK'nın dayanım performansı büyük ölçekli DKK'nın performansına göre qu ve quu değerleri bakımından sırasıyla %40 ve %30 daha fazla iken, konsolidasyon ve permeabilite özelliklerini temsil eden Cc ve k değerlerine göre sırasıyla %20 ve %45 daha az elde edilmiştir. Küçük ve büyük ölçekli DKK tasarımlarında; kür süresi (t), bağlayıcı faktörü (?) ve içeriği (aw) arttığında qu, quu ve RI artarken, Cc ve k azalmaktadır. Karışımın toplam su/bağlayıcı oranı (WT:Wb) ve/veya likitlik indisi (IL,mix) arttıkça qu ve quu azalırken, Cc ve k artmaktadır. DKK performansının en iyi olduğu durum IL,mix=(1.2-1.3)IL olduğunda elde edilmiştir. SEM görüntüleri ile DKK içyapısındaki boşlukların durumu, C-S-H, C-A-H jelleri, CH plakaları ve etrenjit iğnelerinin oluşumu gözlenerek DKK performansı ile ilişkilendirilmiştir. Deneysel ve istatistiki çalışmalardan elde edilen sonuçlar literatürle uyumlu olmuştur.
Citation - WoS: 1
Effect of Pile Geometry and Soil Saturation Degree on Point Bearing Capacity for Bored Piles in Sands
(2024) Yenginar, Yavuz; Fidan, Bekir; Olgun, Murat
In the present paper, an experimental study was conducted to determine the factors affecting the point bearing capacity of pile foundations constructed in dry and saturated sandy soils. Model piles were installed as reinforced concrete bored piles cast-in-situ. Model pile foundations of various geometries resting at different depths in homogeneous sand of different saturation degrees (%0-100) were loaded statically to failure. The test results showed that the bearing capacity of piles did not significantly affect by the loading rate. At most 10% difference was observed in pile bearing capacity when the loading rate was between 0.7 and 2.5 mm/min. Subsequently, the load bearing capacities of the piles were determined at a specified constant loading rate. The point and total capacities of the piles were measured separately in the experiments, then test results were compared with theoretical values. Pile point capacities provided from pile load tests are smaller than the theoretical values. The differences between experimental and theoretical results have been attributed to the Nq values. The Nq values not only dependent on the internal friction angle of the soil but also the saturation degree of the soil, the pile diameter, and the effective stress. Nq values decrease since the pile length/pile diameter ratio increases.
Investigating the Construction Parameters of Deep Mixing Columns in Silty Soils
(2021) Olgun, Murat; Mobark, Ahmed A. M. M.; Yenginar, Yavuz
In the present research, the optimum condition of the grout consisting of cement, fly ash, superplasticizer, and water was determined to produce the most durable and impermeable deep mixing columns (DMC) on silty soils. It is aimed to reduce the grout cost and environmental pollution by using high-rate fly ash in the grout. Superplasticizer additive was used to increase the flow consistency of grout consisting of high-rate fly ash. The design of the experiments was made using the 5-parameter and 4-level L16 orthogonal array table specific to the Taguchi method. Accordingly, the unconfined compression strength (qu) and the permeability coefficient (k) of the soil-binder mixtures at the end of the 7- and 28-days curing time were determined. According to the test results, regression analyzes were performed and models with high reliability were created for qu and k. As a result of optimization studies, to produce DMC having high strength and low permeability, grout content should be consisting of 14% cement, 14% fly ash (ratio of fly ash in the binder is 50%), 2.68% super plasticizer additive, and 0.95 water/binder ratio. The pozzolanic reactions in soil-binder samples with different grout contents were examined by SEM analysis.
Optimizing Construction Parameters of Dmc in High Plasticity Soils
(2019) Yenginar, Yavuz; Olgun, Murat
In this study, the parameters affecting the construction of deep mixing columns (DMC) in high plasticity clayey soil in the laboratory environment were investigated. For this purpose, laboratory type deep mixing machine, mixing blade, slurry pump are designed and manufactured. The characteristics of the soil to be improved (water content or consistency of the soil), slurry characteristics (cement dosage and water/cement ratio) and the selected system parameters in the column manufacturing (the drilling speed of the drill body, the rotation speed of the mixing blades, the nozzle diameter) affect the homogenous and continuous column formation. In this study, the clayey soil was placed into the 60 cm diameter and 110 cm high tank with the targeted water content (35-45-52%) and consolidated under a certain pre-consolidation pressure. Thus, a soil environment has been formed close to the field conditions. Then 30 cm diameter and 60-70 cm high DMC was manufactured with the laboratory type deep mixing machine. For the column production, the cement dosage was 250-325-400 kg/m3 and the water/cement ratio was 1. During column construction, the penetration rate of the drill body is adjusted to transfer the neccessary cement grout to the soil. The rotational speed of the mixing blade is 60-80-100 rpm. There are 4 injection nozzles on the mixing blade. The diameter of these nozzles varies between 2-3-4 mm. In order to understand the relation between the above mentioned parameters and their levels, a test program was created according to Taguchi's 4-parameters and 3-levels L9 design table. Column was produced according to the experimental program and core samples were taken from the columns after 28 days. A term of improvement ratio (ratio of DMC strength to untreated soil strength) was defined to evaulate experimental findings by statistical methods as S/N analysis, ANOVA, and regression analysis, and then optimum construction parameters were determined.
Citation - WoS: 12
Citation - Scopus: 14
Optimizing Installation Parameters of Dm Columns in Clay Using Taguchi Method
(Springer Heidelberg, 2023) Yenginar, Yavuz; Olgun, Murat
In this study, the installation parameters of the deep mixing (DM) column were optimized to manufacture a homogeneously mixed column and to reduce variability in the strength of the column. DM columns, 30 cm in diameter and 70 cm in length, were manufactured on clayey soils of different consistencies using a DM machine and slurry batch plant in the laboratory. The strength of DM columns and soil improvement ratio were investigated using installation parameters such as the cement dosage, the rotational speed of the mixing blades, the nozzle diameter, and the liquidity index of the soil. The design of experiments was conducted using the Taguchi method with a 4-parameter and 3-level L9 orthogonal array table. According to the observations during the installation of columns, the mixing time required to obtain a homogeneous soil-slurry mixture depended on the liquidity index of the fresh soilcrete. In addition, an interface layer, which is stiffer than the unimproved clay, was observed between the column and the unimproved soil. The thickness of the interface layer is 3-8% of the column diameter. Statistical evaluation was performed with S/N (signal-to-noise) and variance (ANOVA) analyses using the 28-day core strength of the columns. Optimum installation parameters were determined as cement dosage of 325 kg/m(3), the rotation speed of the mixing blade is 80 rpm, nozzle diameter is 3 mm, and liquidity index of the soil is 1. The coefficient of variance for strength values decreased from 0.29 to 0.1 when the column was constructed with optimum installation parameters.
Triaxial Compression Test Results on Dmc Samples Prepared by Using Different Soil Types
(2019) Yenginar, Yavuz; Olgun, Murat
In this study, the effects of cement, fly ash and super plasticizer, improver materials by adding into the grout, on soil-binder mixing columns called as deep mixing columns (DMC) are investigated. Fly ash is a waste product emerging from burning in the thermal power plant. By evaluating waste materials in this way, environmental pollution will be reduced directly and cement usage and carbon emissions caused by cement production will be reduced indirectly. By using super plasticizer into the grout, less porous and permeable elements with more structural strength will be manufactured. In order to achieve these goals, an experimental program was developed using statistical and experimental design methods. It is desired to determine the optimum grout quantity and consistency required to maximize the strength of the column manufactured with DMM in silty soils and silty sands. For this purpose, the amounts of fly ash (0-40%), cement (3-11%), super plasticizer additive (0.5-2%) and water/binder percentage (0.5-1.25%) were chosen as variables to form grouting material. Experimental studies have been carried out using Taguchi method, which is a powerful optimization technique, using 5-parameter and 4-level L16 design table. Undrained-unconsolidated triaxial test specimens were prepared in PVC tubes with diameter of 47 mm and length of 100 mm for each design for curing time of 28 days. As a result of the experiments, deviator stress of the soil-binder mixture was found for each design.