محيا شرف الاسلامي

The rapid development of urban rail transit systems has significantly facilitated mobility in large metropolitan areas. Slab track systems, owing to their superior geometric stability, reduced maintenance requirements, an‎d longer service life compared to ballasted tracks, have been increasingly implemented in railway networks, particularly in urban metro lines an‎d high-speed railways. Nevertheless, the constituent components of these systems are subjected to various deterioration mechanisms throughout their service life, which may alter the dynamic behavior of the track system, amplify vibration levels, an‎d reduce ride comfort. Prolonged an‎d repetitive vibrations can lead to structural damage within the track system an‎d induce vibration transmission to adjacent buildings, thereby adversely affecting urban living conditions an‎d productivity. Therefore, eva‎luating the dynamic performance of slab track systems under deteriorated conditions is of considerable importance. In this study, the effects of component deterioration in slab track systems on the propagation of railway-induced vibrations were investigated using finite element (FE) modeling. First, the critical track components contributing to vibration amplification were identified an‎d examined. Subsequently, a two-dimensional finite element model of the slab track system was developed in Abaqus, consisting of two sub-models: a load generation model an‎d a wave propagation model. Various deterioration scenarios were simulated, including degradation in the floating slab track (FST) system resulting from changes in stiffness an‎d damping properties of the resilient layer beneath the slab. Rail irregularities were incorporated into the load generation sub-model. In the next stage, the vibration response of the system was extracted from the wave propagation sub-model in terms of acceleration an‎d velocity time histories at key locations such as the slab an‎d tunnel wall. The results were analyzed in both time an‎d frequency domains an‎d validated against field measurements obtained from vibration tests conducted on Line 6 of the Tehran Metro. The simulation results indicate that deterioration in the resilient layers beneath the slab (types SR18, SR28, an‎d SR55 with low, medium, an‎d high initial stiffness classes, respectively) leads to an increase in dynamic stiffness by approximately 50%, 40%, an‎d 30%, along with a slight but significant reduction in damping. These changes result in an increase in the dominant frequency of the system, higher acceleration-based vibration indices—including root mean square (RMS) acceleration, peak particle acceleration (PPA), an‎d peak-to-peak acceleration—an‎d a shift of vibrational energy toward the mid-frequency ban‎d. This behavior reflects a substantial degradation in the vibration isolation performance of the resilient layers. The increase in dynamic stiffness combined with reduced damping not only intensifies vibration wave propagation but may also accelerate component deterioration an‎d reduce the overall service life of slab track systems. The findings of this study can contribute to improving design methodologies, optimizing maintenance strategies, an‎d developing advanced condition monitoring approaches for slab track infrastructure.

خطوط صلب , ارتعاشات ريلي , زوال اجزاي خط , شبيه سازي عددي , مدلسازي اجزاي محدود

slab track , Rail Way Vibrations , Track Component Deterioration , Numerical Simulation , Finite Element Modeling

Mahya Sharafoleslami

Dr.Mir Mohammad Sadeghi