Hamidreza Heydari

• PhD
• Assistant Professor of Civil and Railway Infrastructure Engineering at Iran University of Science and Technology

Utilizing the ballast layer with more durable and stable characteristics can help avoid significant expenses due to decreased maintenance efforts. Strengthening the ballast layer with different types of reinforcements or substituting the stone aggregates with the appropriate granular materials could potentially help to achieve this goal by reducing...

One of the primary challenges in the railway industry revolves around achieving a comprehensive and insightful understanding of track conditions. The geometric parameters and stiffness of railway tracks play a crucial role in condition monitoring as well as maintenance work. Hence, this study investigated the relationship between vertical ballast s...

One of the inevitable places where the railway track stiffness suddenly changes is the junction points of the slab and ballasted tracks. In these junction areas, differences in the vertical stiffness of the track cause an increase in wheel–rail contact forces that lead to some crucial damages in railway tracks such as rail defects, hanging sleepers...

The utilization of geogrids used to ballast reinforcement has been widely investigated by researchers in the technical literature. This technique aims to enhance the load-bearing capacity of ballast while mitigating its degradation by minimizing breakage and settlement. This research proposes a novel approach to enhancing ballast shear behaviour in...

The interaction among ballast particles, known as ballast shear interlocking (BSI), significantly influences the dynamic responses of railway track. This research presents a meticulously derived mathematical formulation for calculating BSI stiffness, which is then validated through experimental data obtained from a novel laboratory test procedure....

Short-span bridges are one of the most frequent infrastructures along railway tracks where railway track stiffness suddenly changes. The sudden variation in the vertical stiffness of railway tracks increases dynamic loads and causes numerous defects in ballasted railroads. Therefore, improving the dynamic performance of railway tracks can be conduc...

Abrupt stiffness variations along the railway track may increase the geometrical and mechanical defects of railway lines. The conjunction points of a railway track with concrete and ballast pavements, which are called slab-ballasted track transitions, are one of the main areas where vertical track stiffness changes sharply. Therefore, the potential...

High-speed rail (HSR) refers to a land transportation system that has a competitive advantage with air mode in terms of speed and safety. High-speed rail is exclusively a rail transport system in which the speed of the fleet does not fall below 200 km/h. On average, the travel speed of 250 km/h is the criterion for accepting a network as a high-spe...

Culverts and bridges are the most common areas on railway lines where abrupt changes of track stiffness can occur. Using auxiliary rails in the transition zone is one option for gradually increasing track stiffness. The study reported in this paper investigated this issue by means of finite-element modelling. A ballasted track with a concrete culve...

ABRUPT TRACK VERTICAL STIFFNESS VARIATIONS ALONG RAILWAY TRACKS CAN LEAD TO INCREASED DYNAMIC LOADS, ASYMMETRIC DEFORMATIONS, DAM-AGED TRACK COMPONENTS, AND CONSEQUENTLY, INCREASED MAINTENANCE COSTS. THE JUNCTION OF SLAB TRACK AND BALLASTED TRACK IS ONE OF THE EXISTING AREAS WHERE VERTICAL TRACK STIFFNESS CAN SUDDENLY CHANGE, THEREFORE REQUIRING A...

An abrupt change in the stiffness of railway tracks at the junction between slab track and ballasted track causes increased dynamic loads, asymmetric settlements, damage of track components, and, consequently, increased maintenance costs. Due to this, a transition zone is usually built at the junction between the ballasted and the ballastless track...

One of the most important problems in the ballasted railway tracks is the inappropriate distribution of stress through the ballast over the subgrade layer, which causes damage to the super/substructure layers. Application of hot mix asphalt (HMA) layer in the forms of underlayment or full depth has been proposed in order to decline the stress conce...

Train-induced vibrations have adverse effects on the structure of a track and its surroundings. It is thus necessary to study and control this issue through efficient measures. Special polyurethane pads that are placed under sleepers have been recently suggested as a solution to this problem. The use of these pads reduces vibrations at their source...

In this paper, a finite-element (FE) model including the track super- and substructure components was developed for seismic analysis of railway track. In the developed model, the beam elements were used to define rails and sleepers as components of track superstructures. Moreover, a series of lumped masses with springs and dashpots was considered f...

In this paper, a finite-element (FE) model including the track super- and substructure components was developed for seismic analysis of railway track. In the developed model, the beam elements were used to define rails and sleepers as components of track superstructures. Moreover, a series of lumped masses with springs and dashpots was considered f...