Browsing by Author "Kaliakin, Victor N."
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Item Column Supported Embankments with Geosynthetic Encased Columns: Parametric Study(Springer International Publishing AG, 2014) Khabbazian, Majid; Meehan, Christopher L.; Kaliakin, Victor N.; Khabbazian, Majid, Meehan, Christopher L., Kaliakin, Victor N.; Meehan, Christopher L. (orcid.org/0000-0002-9721-6275); Kaliakin, Victor N.Three-dimensional finite element analyses were performed to investigate different factors that affect the behavior of column supported embankments (CSEs) that are constructed using geosynthetic encased columns (GECs) as the deep foundation elements. Analyses were performed to study the influence of the geosynthetic encasement on the behavior of granular columns (GCs) in CSEs. Stress reduction ratios (SRRs) obtained from finite element analyses were compared to those calculated from ten different analytical solutions. Parametric analyses were also carried out to study the effect of variations in the stiffness of the encasement, the area replacement ratio, and the length of the geosynthetic encasement on the performance of CSEs. Finally, the sensitivity of the numerical results, particularly the lateral displacement of GECs, to the constitutive model that was used to simulate the behavior of the granular column material was examined. Numerical results showed that encasing a GC in a CSE not only improves the performance of the CSE but also enhances the behavior of the GC. No agreement was found between the calculated values of the SRR from finite element analyses and those from existing analytical solutions.Item Column Supported Embankments with Geosynthetic Encased Columns: Validity of the Unit Cell Concept(Springer International Publishing AG, 2015) Khabbazian, Majid; Kaliakin, Victor N.; Meehan, Christopher L.; Meehan, Christopher L.; Kaliakin, Victor N.Column supported embankments (CSEs) are used to overcome common problems associated with the construction of embankments over soft compressible soils. The use of granular columns as deep foundation elements for CSEs can be problematic in soft soils due to the lack of adequate lateral confining pressure, particularly in the upper portion of the column. Using a high-strength geosynthetic for granular column confinement forms geosynthetic encased columns (GECs); the confinement imposed by the geosynthetic increases the strength of the column, and also prevents its lateral displacement into the soft surrounding soil. This paper presents the results of finite element analyses of a hypothetical geosynthetic reinforced column supported embankment (GRCSE) (i.e., a CSE underlain by geosynthetic reinforcement) that is constructed with GECs as the deep foundation elements. Full three-dimensional(3-d), 3-d unit cell, and axisymmetric unit cell analyses of the GRCSE were carried out to investigate the validity of the unit cell concept. The effect of the degree of nodal constraint along the bottom boundary when numerically modeling GRCSEs was also studied in this paper. Numerical results show that a full 3-d idealization is required to more precisely determine the tension forces that are produced in the geosynthetic reinforcement that underlies the GRCSE. A number of design parameters such as the average vertical stresses carried by the GECs, lateral displacement of the GECs, and the maximum settlement of the soft foundation soil, however, can be successfully calculated using unit cell analyses.Item Comparative Analysis of Static and Dynamic Tests of Piles in Difficult Soil Conditions of Kazakhstan(International Journal for Computational Civil and Structural Engineering, 2022-06-24) Zhussupbekov, Ascar Zh.; Yessentayev, Ascar U.; Kaliakin, Victor N.; Drozdova, Irina V.A comparative analysis of the results of field tests to determine the bearing capacity of a pile at the facilitys in the Nur-Sultan city and Petropavlovsk city. The aim of the study was to carry out a comparative analysis of the results of dynamic and static tests in the two construction site in order to identify the difference in performance. This article provides programs and results of tests with static indentation load and dynamic load on a pile in different two of the construction site under different soil conditions. The results of the comparative analysisare the following: Dynamic tests are needed for a preliminary assessment of the dynamic bearing capacity and the possibility of driving piles in different soil conditions. The bearing capacity of the pile, determined by dynamictests, is slightly lower than during static tests, the difference between the results is 11 and 17%.Item General response observed in cyclically loaded cohesive soils(Nueva Granada Military University | Bogota Colombia, 2016-02-04) Leal, Andres Nieto; Kaliakin, Victor N.; Andrés Nieto Leal, Victor N. Kaliakin; Kaliakin, Victor N.The response of cohesive soils subjected to cyclic loading is affected by different factors; the most important are soil type, stress or consolidation history, and specific test conditions. To better understand the behavior of cohesive soils subjected to cyclic loading, beginning in early 1960's, a rather substantial body of experimental work has been performed. This has involved different types of soils, tested at different values of overconsolidation ratio, and subjected to different cyclic loading histories. This paper compiles the most important findings of the aforementioned experimental work on cohesive soils. It summarizes the general behavioral trends observed for cyclically loaded cohesive soils. Besides, several key characteristics of cyclically loaded cohesive soils that any rational mathematical simulation must account for have been identified, thus offering the general trends that should be taken into account in the development of new constitutive models used in predicting the response of such soils.Item Numerical Study of the Effect of Geosynthetic Encasement on the Behaviour of Granular Columns(ICE Publishing, 2010) Khabbazian, Majid; Kaliakin, Victor N.; Meehan, Christopher L.; Khabbazian, M., Kaliakin, V. N., Meehan, C. L.; Meehan, Christopher L. (orcid.org/0000-0002-9721-6275)In very soft soils, the use of granular columns can be restricted due to the lack of adequate lateral confining pressure. In these conditions, the columns can be encased by a suitable geosynthetic to provide the required confining pressure and to increase their bearing capacity. Using a high-strength geosynthetic for confinement not only increases the strength of a granular column, but also prevents lateral displacement of the column into the very soft surrounding soil. This paper describes three-dimensional finite element analyses carried out to simulate the behaviour of a single granular column with and without encasement in a very soft clay using the computer program ABAQUS. Comprehensive numerical analyses were performed to study the influence of the geosynthetic stiffness, the friction and dilation angle of the column material, the length of geosynthetic encasement, the diameter of the column, the length of the column and the coefficient of in situ lateral earth pressure. Model results show that the stress–settlement behaviour of granular columns can be significantly improved by encasing them. The stiffness of the encasement was found to have a major effect on the stress–settlement response of encased columns and their associated load-carrying capacity. For partially encased columns, the optimum length of encasement was found to be a function of the stress that is applied to the column.Item Three-dimensional stress-strain and strength behavior of silt-clay transition soils(Canadian Geotechnical Journal, 2023-04-10) Anantanasakul, Pongpipat; Intharachart, Phimmawat; Kaliakin, Victor N.The effect of silt content on the mechanical behavior of silt-clay transition soils under three-dimensional stress conditions is presented. Undrained true triaxial tests with constant b values were performed on normally consolidated specimens of silt-clay transition soils created from the same base clay and non-plastic silt, however, with systematically varying gradations. With increasing amount of non-plastic silt, the cohesive soils exhibit less contractive tendencies, stiffer stress-strain response and larger shear strength. The magnitude of intermediate principal stress, as indicated by the b value, also strongly influences the stress-strain relations, pore pressure behavior and both total and effective failure surfaces. Although the transition soils exhibit overall clay-like behavior, more pronounced frictional characteristics, as indicated by the shapes of the failure and plastic potential surfaces, were exhibited with increasing silt content.