@phdthesis{Shahraki,
  author    = {Shahraki, Mojtaba},
  title     = {Numerical Analysis of Soil Behavior and Stone Columns Effects on the Railway Track},
  doi       = {10.25643/bauhaus-universitaet.4015},
  url       = {http://nbn-resolving.de/urn:nbn:de:gbv:wim2-20191111-40159},
  school      = {Bauhaus-Universit{\"a}t Weimar},
  abstract  = {Railway systems are highly competitive compared with other means of transportation because of their distinct advantages in speed, convenience and safety. Therefore, the demand for railway transportation is increasing around the world. Constructing railway tracks and related engineering structures in areas with loose or soft cohesive subgrade usually leads to problems, such as excessive settlement, deformation and instability. Several remedies have been proposed to avoid or reduce such problems, including the replacement of soft soil and the construction of piles or stone columns. This thesis aims to expand the geotechnical knowledge of how to improve subgrade ballasted railway tracks, using stone columns and numerical modeling for the railway infrastructure. Three aspects are considered: i) railway track dynamics modeling and validation by field measurements, ii) modeling and parametric studies on stone columns, and iii) studies on the linear and non-linear behavior of stone columns under the dynamic load of trains. The first step of this research was to develop a reliable numerical model of a railway track. The finite element method in a time domain was used for either a 2D plane strain or 3D analysis. Individual methods for modeling a train load in 2D and 3D were implemented and are discussed in this thesis. The developed loading method was validated with three different railway tracks using obtained vibration measurements. Later, these numerical models were used to analyze the influence of stone column length and train speed in the stress field. The performance of the treated ground depends on various parameters, such as the strength of stone columns, spacing, length and diameter of the columns. Therefore, the second step was devoted to a parameter study of stone columns as a unit cell with an axisymmetric condition. The results showed that even short stone columns were effective for settlement reduction, and area of replacement was the main influential parameter in their performance. The third part of this thesis focuses on a hypothetical railway-track response to the passage of various train speeds and the influence of stone-column length. The stress-strain response of subgrade is analyzed under either an elastic-perfectly plastic or advanced constitutive model. The non-linear soil response in the finite element method and the impact of train speed and stone column length on railway tracks are also evaluated. Moreover, the reductions of induced vibration - in both a horizontal and a vertical direction - after improvement are investigated.},
  subject      = {Eisenbahn},
  language  = {en}
}
@misc{Germerott2004,
  type      = {Master Thesis},
  author    = {Germerott, Ren{\´e}},
  title     = {Variantenuntersuchung f{\"u}r eine dauerhafte Bahndammsanierung unter zu Hilfenahme numerischer Methoden},
  doi       = {10.25643/bauhaus-universitaet.350},
  url       = {http://nbn-resolving.de/urn:nbn:de:gbv:wim2-20111215-3500},
  school      = {Bauhaus-Universit{\"a}t Weimar},
  year      = {2004},
  abstract  = {Das Ziel der Arbeit war es, die Standsicherheit eines Bahndammes im Vergleich der in Deutschland g{\"u}ltigen Vorschriften (DIN 1054 und Eurocode 7) zu untersuchen. Sollte sich dabei herausstellen, dass der Bahndamm in der gegebenen Situation die Standsicherheitsanforderungen nicht erf{\"u}llt sollten verschiedene Sanierungsvarianten vorgeschlagen und f{\"u}r eine Vorzugsvariante die wichtigsten Nachweise durchgef{\"u}hrt werden. Zun{\"a}chst wurden die Allgemeinen Grundlagen der zur Zeit in Deutschland g{\"u}ltigen Vorschriften erl{\"a}utert und anschließend auf das konkrete Projekt bezogen gegen{\"u}bergestellt. Es stellte sich heraus, dass die Anforderungen an die Standsicherheit bei Berechnung nach beiden Vorschriften nicht erf{\"u}llt werden konnten. Somit war es notwendig f{\"u}r die gegebene Situation m{\"o}gliche Sanierungsvorschl{\"a}ge zu entwickeln. Diese wurden anschließend kurz vorgestellt und erl{\"a}utert. Schließlich wurden f{\"u}r die Vorzugsvariante die wichtigsten Nachweise im Vergleich der Vorschriften (DIN 1054 und Eurocode 7) durchgef{\"u}hrt und verglichen.},
  subject      = {Aktiver Erddruck},
  language  = {de}
}