The aim of this study is to develop coupled matrix formulations to characterize the dynamic interaction between the vehicle, track, and tunnel. The vehicle–track coupled system is established in light of vehicle–track coupled dynamics theory. The physical characteristics and mechanical behavior of tunnel segments and rings are modeled by the finite element method, while the soil layers of the vehicle–track–tunnel (VTT) system are modeled as an assemblage of 3-D mapping infinite elements by satisfying the boundary conditions at the infinite area. With novelty, the tunnel components, such as rings and segments, have been coupled to the vehicle–track systems using a matrix coupling method for finite elements. The responses of sub-systems included in the VTT interaction are obtained simultaneously to guarantee the solution accuracy. To relieve the computer storage and save the CPU time for the large-scale VTT dynamics system with high degrees of freedoms, a cyclic calculation method is introduced. Apart from model validations, the necessity of considering the tunnel substructures such as rings and segments is demonstrated. In addition, the maximum number of elements in the tunnel segment is confirmed by numerical simulations.

Rolling stock connection systems are key to running longer and heavier trains as they provide both the connections of vehicles and the damping, providing the longitudinal suspension of the train. This paper focuses on the evolution of both connection and stiffness damping systems. Focus is on freight rolling stock, but passenger draw gears are also examined. It was found that connection systems have evolved from the buff and chain system used in the pioneer railways of the 1800s to the modern auto-coupler connection systems that are in-service worldwide today. Refined versions of the buff and chain coupling are, however, still in use in the EU, UK, South America and India. A wide range of auto-coupler systems are currently utilised, but the AAR coupler (Janney coupler) remains the most popular. A further variation that persists is the SA3 coupler (improved Wilson coupler) which is an alternative auto-coupler design used mainly throughout the former Soviet Union. Restricting the review to auto-coupler systems allowed the paper to focus on draft gears which revealed polymer, polymer-friction, steel spring-friction, hydraulic draft gears and sliding sill cushioning systems. Along with the single compressive draft gear units balanced and floating plate configurations are also presented. Typical draft gear acceptance standards are presented along with modelling that was included to aid in presentation of the functional characteristics of draft gears.

The aerodynamic performance of high-speed trains passing each other was investigated on a simply supported box girder bridge, with a span of 32 m, under crosswinds. The bridge and train models, modeled at a geometric scale ratio of 1:30, were used to test the aerodynamic forces of the train, with the help of a designed moving test rig in the XNJD-3 wind tunnel. The effects of wind speed, train speed, and yaw angle on the aerodynamic coefficients of the train were analyzed. The static and moving model tests were compared to demonstrate how the movement of the train influences its aerodynamic characteristics. The results show that the sheltering effect introduced by trains passing each other can cause a sudden change in force on the leeward train, which is further influenced by the wind and running speeds. Detailed analyses related to the effect of wind and train speeds on the aerodynamic coefficients were conducted. The relationship between the change in aerodynamic coefficients and yaw angle was finally described by a series of proposed fitting formulas.

During traction and braking of multiple-unit trains, substantial longitudinal dynamic forces might occur in couplers due to the non-optimal distribution of traction and braking forces generated by self-propelled carriages. These dynamic forces might create shocks affecting the reduction of endurance of the weakest train structural components primarily. Thus, the overall operational safety of the train is also lowered. The purpose of the paper is to develop a new control system to supervise the activities related to the longitudinal dynamics of each train carriage in a multiple-unit train to reduce the longitudinal coupler forces acting during train traction and braking. The hierarchical structure of the control system consists of two levels. The first master level of control works like standard cruise control. However, the reduction of longitudinal coupler forces is achieved by applying a second level of slave control systems with a control configuration of feedback compensation.

Concrete-plate fences have been widely adopted for windblown sand control and mitigation along railways. However, the inclination angles of inserting the concrete plate with respect to the vertical direction, i.e., straight or obliquely inserted concrete plates (SIP or OIP), significantly influence the efficiency of sand-control. This study performs a comparative evaluation of the SIP and OIP sand-control fences using wind tunnel testing and field monitoring data collected from the Lanzhou–Wulumuqi High-Speed Railway Project. The results show that the fence’s ability to reduce the wind speed and the sand-retaining efficiency gradually weakens with the increasing wind speed. Compared with the SIP fence, the OIP fence has a better wind speed reduction capability, stronger ability to capture fine particles below the top of the fence; it is more efficient for sand-retaining and induces stronger eddy intensity. Generally, the wind tunnel test and field monitoring results are consistent, whereas wind tunnel tests incline to overestimate wind speed reduction and sand-control efficiency. The study also finds that the aeolian sand accumulated around the fence can weaken the protection efficiency, and hence cleaning the aeolian sand accumulated around the fence should be done periodically to ensure the designed functions.

Piled embankments have been extensively used for high-speed rail over soft soils because of their effectiveness in minimizing differential settlement and shortening the construction period. Stress concentration ratio, defined as the ratio of vertical stress carried by pile heads (or pile caps if applicable) to that by adjacent soils, is a fundamental parameter in the design of piled embankments. In view of the complicated load transfer mechanism in the framework of embankment system, this paper presents a simplified analytical solution for the stress concentration ratio of rigid pile-supported embankments. In the derivation, the effects of cushion stiffness, pile–soil interaction, and pile penetration behavior are considered and examined. A modified linearly elastic-perfectly plastic model was used to analyze the mechanical response of a rigid pile–soil system. The analytical model was verified against field data and the results of numerical simulations from the literature. According to the proposed method, the skin friction distribution, pile–soil relative displacement, location of neural point, and differential settlement between the pile head (or cap) and adjacent soils can be determined. This work serves as a fast algorithm for initial and reasonable approximation of stress concentration ratio on the design aspects of piled embankments.