Insulated rail joints (IRJs) play a crucial role in modern railway systems. They serve the critical function of electrically isolating rail segments through the placement of an insulating material, known as an end plate, between two rail ends. This insulating material is necessary to define track segments, which makes it possible to determine the position of trains within the railway system. Knowing a train’s position is key to ensuring efficiency, reliability, and safety. While these joints are highly important, they are also vulnerable. The interruption in rail geometry results in a complex interaction between wheel and rail, giving rise to high dynamic impact forces. Traditional IRJs, or squared IRJs, have the cut between the rail ends orthogonal to the rail. In this thesis, an alternative design with a non-orthogonal junction angle is analyzed.

The primary goal of this thesis is to determine how the junction angle influences both the global wheel-rail interaction and the local contact pressure at the wheel-rail interface. To achieve this, the thesis is split into two parts: (1) the global wheel-rail interaction analysis, which studies the influence of the junction angle on the interaction between the wheel and rail using simplified geometries in a kinematic approach, and (2) a local wheel-rail interface analysis, which studies the effect of the junction angle on an assumed uniform contact pressure between wheel and rail.

The global analysis revealed the possibility of two distinct contact scenarios, depending on lateral wheel position and dip angles greater than zero. In contact scenario 1, the effective geometry and the resulting vertical impulse remained identical to those of squared joints. However, in contact scenario 2, the active geometry of the joint changes, leading to an increase in vertical impulse of the wheel’s center of mass. Additionally, the introduction of the junction angle increased the likelihood of less favorable contact conditions for contact scenario 1 and guaranteed less favorable contact conditions for contact scenario 2. The local analysis showed that uniform contact pressure between the wheel and rail increases slightly for non-orthogonal junction angles with dip angles near zero. For small junction angles (resulting in a long cut in the longitudinal direction), outside of the practical range, the rate of change of the contact pressure was greatly reduced.

The study has shown that insulated rail joints with non-orthogonal junction angles within the practical range do not provide significant improvements in dynamic performance compared to traditional squared joints. However, due to the assumptions made in this model, the complexity of the rail geometry was significantly simplified, and material elasticity was not considered. These limitations are expected to affect the contact behavior and could affect the results. This should be investigated further. The second model demonstrates that for junction angles within the practical range, the assumed uniform contact pressure increased slightly. However, for very small junction angles, which result in impractically elongated joints, the rate of change in uniform contact pressure can be greatly reduced.

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The Mekong Delta is facing some complicated challenges in the near future. Its geographical location and the fact that it is a delta result in low elevation levels which makes it vulnerable to inundation. This problem will only become bigger in the future due to the effects of climate change. To get funding from organisations like the world bank it is important to propose multiple solutions that are beneficial to multiple parts of society. It is favourable to split
a complex system like the Mekong Delta into subsystems to make it more feasible to build realistic models. The subsystem defined in this report is the Hau River estuary. This area mainly suffers from riverine inundation caused by tidal variation in the South Chinese Sea. The biggest city in the region is Can Tho with 1.3 million inhabitants.

The research question is: Which integrated solutions reduce riverine inundation problems in the Hau River estuary while also considering socio-economical aspects? To answer this research question the following four solutions are proposed and designed.

• Discharge sluice in the mouth of the Hau River to reduce the tidal influence

• Wetland with a double levee system and buffer zones to reduce peak discharge

• Bypass channel to the Gulf of Thailand to reduce discharge during the wet season

• Protection of valuable assets and adaptation of local citizens to the new natural balance

Based on desired discharges and water levels preliminary design parameters of the proposed hydraulic structures were determined. The effectiveness of these solutions was assessed based on their ability to reduce the water level in Can Tho. The reduction that the discharge sluice achieved was determined with a zero-dimensional model, whereas the water level reduction that the wetlands and bypass option achieved were determined by Delft3D models. The discharge sluice performed best in reducing the water level in Can Tho, as it opposes the tidal influence in the Hau River.

To assess the quality of the solutions relative to each other a best-worst multi-criteria analysis is done. In this assessment other factors such as financial aspects, socio-economics and transportation are taken into account. The most important criteria are flood reduction and funding opportunities. According to the assessed criteria, the discharge sluice and the wetland are the best-scoring solutions. These solutions have the most potential in reducing the river inundation problems in the Hau River estuary. This does not mean that the bypass and adaptation solutions should be neglected or are not useful. For a complex problem in a complex system like the Hau River estuary, one solution is not going to solve all the problems. A good balance between different aspects has to be determined by also considering other problems like sand mining, subsidence and salt intrusion. ... Read more