Amir Safizadeh’s research while affiliated with Iran University of Science and Technology and other places

Track longitudinal resistance is defined as the resistance generated by sleeper-ballast and rail-sleeper interactions against the imposing forces, which cause longitudinal displacement. This component is one of the important indicators of the continuously welded rail (CWR) track's stability and lateral resistance against buckling. In this paper, the track longitudinal resistance (TLR) and track longitudinal stiffness (TLS) have been investigated to determine the contribution of the fastening system and sleeper in TLR and TLS through laboratory tests and a numerical model. A track panel with one to eight sleepers fastened with 100, 80 and 60 Nm prestressed torqe-force applied to fastening screws was loaded. The average contribution of the sleepers in TLR in the case with a rail-pad for 100 and 60 Nm torque-forces is approximately 30% and 75%, respectively, and the average contribution of the fastening system in the same state is approximately 70% and 25%, respectively.

The longitudinal resistance of ballasted tracks is due to the longitudinal interaction of rail-fastener and ballast-sleeper. Longitudinal resistance is under the effect of various factors as well as the applied vertical load of the running train over the track structure. In this paper, the effect of vertical load on the longitudinal resistance of the ballasted railway track is experimentally and numerically investigated. First, the longitudinal resistance of a 3-m test panel with five B70 concrete sleepers under 0, 100, 200, and 300 kN vertical load were investigated. Second, a three-dimensional model of the track was developed using Abaqus software. Finally, the results of experiments and modeling were compared and the numerical modeling is validated based on tests’ results. In each test, track longitudinal stiffness (TLS) and track longitudinal resistance force (TLRF) were calculated. According to laboratory results, TLS was increased by 3.36, 3.63, and 3.83 times with increasing the vertical load as 100, 200, and 300 kN, respectively. In the mentioned order the increment values for TLRF were increased 2.1, 2.74, 2.97 times. Likewise, the numerical results of TLRF for the above-mentioned load order illustrated increasing values as high as 2.1, 2.6, and 2.81 times, respectively.