بررسي و ارزيابي مقايسه‌اي روش‌هاي مختلف بهبود عملكرد ارتجاعي پابندهاي مورد استفاده در خطوط دالخط راه‌آهن

inser‎tion loss , Vibration redaction , Slab Track , Elastic layer , Loss factor , Resilient Fasteners , Preload

Comparative investigation on improvement of elastic behavior of various in railway system rail fasteners used in slab track system

مهندسي راه آهن و برنامه ريزي حمل و نقل

Nowadays, the use of slab tracks is prioritized over ballasted track layouts for urban transportation networks. One of the reasons for this preference is the lower maintenance an‎d repair costs compared to ballasted track layouts. Although slab track systems offer several advantages, their main drawback is their higher stiffness compared to ballasted tracks. An efficient solution to this issue is the use of elastomeric materials an‎d resilient fastening systems as components of the railway track structure. Studies conducted on the dynamic behavior of slab tracks can be classified into two categories: those focusing on eva‎luating the elastic behavior of individual fastening components an‎d those assessing the overall elastic behavior of the integrated fastening system. The objective of this thesis is to determine the effectiveness of different fastening systems in regulating the dynamic behavior of ballastless rail tracks. In recent years, significant efforts have been made by both industry an‎d researchers to eva‎luate properties related to improved elastic performance, such as static stiffness parameters, dynamic stiffness, inser‎tion loss index, an‎d damping factor. However, the impact of different fastening systems an‎d pad materials on these parameters has not been adequately considered. To address this gap, comprehensive experimental measurements were conducted in this study. The experiments were performed on six fastening system prototypes, including the W14 fastening system with polyethylene an‎d dimpled chloroprene rubber rail pads, as well as a four-hole baseplate fastening system with SKL1 spring clips an‎d high-density polyethylene, dimpled chloroprene rubber, polyurethane, an‎d natural rubber baseplate pads. The study then carried out a parametric analysis of the experimental results, eva‎luating the influence of inser‎tion loss index, static stiffness, dynamic stiffness, an‎d damping factor. The rigid fasteners, labeled as "RF" in this thesis, are those with static stiffness ranging from 30 to 73 kN/mm, while the resilient fasteners, labeled as "RRF," have static stiffness between 11 an‎d 27 kN/mm. The dynamic stiffness of rigid fasteners varies between 38 an‎d 89 kN/mm, whereas that of resilient fasteners falls within the range of 12 to 33 kN/mm. The results indicate that the highest inser‎tion loss index corresponds to the RRF-PU fastening system, which is a four-hole baseplate fastening system with an SKL1 spring clip an‎d a polyurethane pad, achieving a value of 5 dB an‎d reducing slab track vibrations by up to 40%. Additionally, the highest damping factor was observed in the RRF-PU fastening system. The obtained results were also compared with theoretical an‎d numerical models.

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