Yazar "Etminan, Ehsan" seçeneğine göre listele
Listeleniyor 1 - 4 / 4
Sayfa Başına Sonuç
Sıralama seçenekleri
Yayın Coupled influence of content, gradation and shape characteristics of silts on static liquefaction of loose silty sands(Elsevier Sci Ltd, 2017-10) Monkul, Mehmet Murat; Etminan, Ehsan; Şenol, AykutStatic liquefaction is a challenging problem of geotechnical engineering as its consequences are generally catastrophic when they occur on site. Previous laboratory studies focused on various factors that could influence the static liquefaction potential of silty sands. Most popular of those investigated factors are stress conditions, deposition method and fines content. The purpose of the present study is to investigate the other possible factors, of which very little is known, mainly focusing on the silt characteristics including grain size distribution, relative size, and shape effects of the silt grain matrix within the sand. Undrained monotonic triaxial compression tests were conducted on thirty sands with varying fmes contents, which were prepared by mixing three base sands (Sile Sands 20/30, 50/55, 80/100) with same geologic origin but with different gradations and three different non-plastic silts (IZ, SI and TI' silts) with different gradations and shape characteristics. The experimental results revealed that each of the mentioned factors had their own influence on static liquefaction behavior of sands. The static liquefaction potential of all the three sands in this study was observed to increase with decreasing coefficient of uniformities of the silt grain matrix (CUsiit) in sands. For a particular base sand, static liquefaction potential was observed to increase with decreasing mean grain diameter ratio (D-50.sand/d(50.silt)) due to change of silt gradation. However, shape characteristics of the silt grains are also found to be another important factor, in certain cases observed to have a greater influence than mean grain diameter ratio criterion. As an example, it was shown that at the same FC, base sand, depositional energy and consolidation stress, angular nature of TT silt potentially caused more meta-stable contacts (weaker grain contacts that promote excess pore pressure generation during shearing) within the specimens than sub-rounded SI silt, which caused specimens with TT silt to be more liquefiable than their counterparts with SI silt. Moreover, it was found that there is a coupled relationship between the fines content and investigated silt characteristics (gradation, mean size, shape effects) on the static liquefaction behavior of sands. The unexpected trend regarding the last finding is that the mentioned influence of silt characteristics (i.e. gradation, size and shape) on static liquefaction of sands becomes more considerable with decreasing fines content at loose states.Yayın Influence of adding fibers on engineering properties of clayey soils(TMMOB İnşaat Mühendisleri Odası, 2023-11-24) Etminan, Ehsan; Dehghanian, Kaveh; Göçkün, Beste Seyla; Koçak Dinç, BesteRecently, research into alternative materials and methods has been ongoing with the goal of creating cuttingedge solutions for building earth structures. In circumstances when other alternative materials are employed, improving the soft soils used for these structures, such as the subgrades of highway embankments, might be essential for implementing sustainable and cost-effective applications. In order to examine the utilization of Polypropylene (PP), Copolymer (CP), and Virgin Homopolymer Polypropylene (VHP) fibers to stabilize two separate high and low-plasticity clay soils, comprehensive laboratory studies have been conducted. To estimate how these mixes would behave during earthquakes, a variety of soils and the aforementioned fibers were created in the lab. The engineering features of these combinations were then studied. Investigations were conducted into the engineering behaviors of the samples as well as the results of the compaction, unconfined compression, CBR, and cyclic triaxial testing. The results of the laboratory study are presented in this work, with a focus on the usage of alternative materials that produce stronger soils during earthquakes, which has positive economic and environmental effects.Yayın Modeling the effects of soil improvement on train induced random ground-borne vibrations(Isik University, 2025-05-01) Bayındır, Cihan; Kesten, Ali Sercan; Etminan, EhsanGround-borne vibrations by railway trains are generated at the rail-wheel interface due to the passage of wheels and due to irregularities of wheels and tracks. These vibrations need to be predicted and controlled during the design and service of the railway for the safety and serviceability of the railway to avoid possible vibrationinduced problems such as settlement and differential settlement due to their compaction effect, liquefaction, and discomfort of people. While such railway vibrations are modeled by different techniques, only a few studies do exist to analyze them in the case of soilimproved conditions. In this study, we propose a mathematical framework to study the effects of soil improvement on the ground-borne vibrations induced by railway trains. We use an experimentally calibrated model that utilizes the evolutionary random process approach to model the time-varying transfer functions between the axles of the train and the fixed observation point. The railway is modeled as a Winkler foundation with rail pads and corresponding transfer functions are used. The target area of this study is the Emin¨on¨u-Alibeyk¨oy Tramway Line in ˙Istanbul, which is under construction. Due to poor soil conditions at the specific stations along the proposed tramway route, soil improvement by the application of geo-synthetics is performed at the site and taken into account in our model. The improvement in soil conditions is modeled as increased vertical soil stiffness in the Winkler foundation of the evolutionary random process model. To model the various tramway loading conditions, both the 5-axle and 6-axle tramway configurations with non-uniform axle spacing are considered. We show that by increasing the vertical soil stiffness ksb, the vibration velocity and acceleration levels can be reduced significantly. By implementing the model proposed, we present the reduction of the vibration velocity and acceleration levels as the functions of soil improvement parameters and discuss our findings and the applicability of the model.Yayın Sustainable soil stabilization using colemanite: experimental and numerical analysis of sandy soils for improved geotechnical properties(Springer Nature, 2025-06-12) Koçak Dinç, Beste; Dehghanian, Kaveh; Etminan, EhsanThis paper discusses the use of colemanite, a boron compound, which is a natural additive to geotechnically improved sandy soils, thus providing an eco-friendly alternative to conventional soil stabilization. Clean angular sand was the base material with the addition of colemanite in amounts of 0%, 5%, 10%, and 15% by dry mass. Various laboratory tests, such as Atterberg limits, void ratio, specific gravity, compaction, permeability, and unconsolidated undrained triaxial tests, were carried out to determine the physical and mechanical characteristics of the produced mixtures. Numerical modeling, adopted by the PLAXIS finite element program, was used to carry out simulations under various conditions for soil profiles to determine and compare soil behavior. The findings revealed that the addition of colemanite significantly reduced permeability and void ratios while enhancing stiffness and strength, with 15% colemanite yielding the best performance. This study is one of those that focuses on the introduction of colemanite, which can also act as an effective stabilizer and is a much greener and more environmentally friendly option. Apart from this, it has other advantages both economically and ecologically by reducing the amount of cement, which is a high carbon source required for building based on this. The discoveries bring in the further development of green geotechnical engineering, which also includes the construction of sustainable infrastructures.
