BİR DEMİRYOLU HATTININ BİRİM ESNEME DİRENCİ ÜZERİNDE ETKİSİ OLAN MEKANİK VE GEOMETRİK NİTELİKLERİN İNCELENMESİ

Öz

Bir demiryolu hattının esneme direnci, hat tasarımında göz önünde bulundurulması gereken en önemli parametrelerden biridir. Bu değerin optimum değerinden düşük olması hattaki oturmaları artırırken, yüksek olması zaman içerisinde hat elemanlarında yıpranmalara neden olur. Bununla birlikte, hat esneme direncinin hat boyunca değişmesiyle dinamik darbe kuvvetleri artarak hattın bozulma sürecini hızlandırır. Hat esneme direnci; hattı oluşturan malzeme özelliklerine, zemin tabakasındaki yerel farklılıklara, hattaki bazı özel durumlara ve hat bileşenlerinin geometrisine bağlı olarak değişmektedir. Aynı zamanda araç-hat etkileşimi de hattın teker kuvvetine karşı gösterdiği tepkiyi etkilemektedir. Bu çalışma, demiryolu hat tasarımlarında esas alınacak olan hat esneme direncini tartışan temel bir kaynak olmayı hedeflemektedir. Bu anlamda yapı-zemin etkileşimini inceleyerek, taşıyıcı zeminin yanı sıra hat üstyapısına ait mekanik ve geometrik özelliklerin, hat ve zeminin bir bütün olarak düşey yükler altındaki tepkisini etkilediğini elastisite teorisine dayalı modeller üzerinden göstermektedir. Daha sonra, araç-hat etkileşimi ele alınmış ve hatta ait tüm parametreler aynı kalsa dahi sadece dingil mesafesindeki değişim nedeniyle hat tepkisinin değiştiği gösterilmiştir. Son olarak, hatta ait mekanik ve geometrik niteliklerin eşdeğer hat esneme direnci üzerindeki etkileri açıklanmıştır.

Anahtar Kelimeler

• Hat esneme direnci
• Hat modülü
• Yatak Modülü
• Hat Üstyapısı
• Araç-Hat Etkileşimi

INVESTIGATION OF THE MECHANICAL AND GEOMETRIC PROPERTIES AFFECTING THE RAILWAY TRACK STIFFNESS

Öz

Track stiffness is one of the most important parameters to be considered in track design. While track stiffness is lower than an optimum value, excessive track displacement occurs, and while it is higher than the optimum, it can cause the deterioration of the track and the components of the track in time. Variation of the track stiffness can increase dynamic impact forces and thus, accelerates the track deterioration. Track stiffness depends on the material properties that constitute track, the local differences in the soil layer, some special conditions, and the geometry of the track components. Also, the track-train interaction affects the reaction of the track against the wheel force. This study aims to be a fundamental resource discussing the track stiffness that will be taken as a basis in railway track design. In this sense, the study shows that the mechanical and geometric properties of the track superstructure affect the common response of the track and soil under the wheel forces by examining soil-structure interaction through elasticity theory-based models. Later, the train-track interaction is discussed and it is shown that even if all parameters of the track remain the same, the track response can change with the axle spacing. Finally, the effects of the mechanical and geometric properties of the track on the equivalent track stiffness are explained.

Anahtar Kelimeler

• Track stiffness
• Track modulus
• Subgrade reaction
• Track superstructure
• Train-track interaction

Kaynakça

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