Exploring seismic warning thresholds for vehicle-track systems through combined shaking table tests and dynamic...

Area of Science:

• Civil Engineering
• Geotechnical Engineering
• Railway Engineering

Background:

• Seismic events pose a significant risk to railway operations, potentially causing vehicle derailment.
• Existing national standards for railway vehicle dynamic performance may not fully account for seismic-induced vibrations.

Purpose of the Study:

• To investigate the dynamic response of vehicle-track systems under seismic loading.
• To determine the primary mechanisms of seismic-induced derailment.
• To evaluate the adequacy of current safety standards and propose improved early warning thresholds.

Main Methods:

• Vehicle-track shaking table model tests using unidirectional and bidirectional seismic waves.
• Three-dimensional finite element numerical simulations of the vehicle-track dynamic model, including track irregularities.
• Analysis of dynamic responses such as wheel load reduction rate and derailment coefficient.

Main Results:

• Horizontal track vibration induced by seismic activity is the main cause of vehicle derailment.
• China's national standard limits for wheel load reduction rate and derailment coefficient are conservative.
• Horizontal seismic waves have a more significant impact on dynamic response than vertical waves when applied simultaneously.
• Numerical simulation results closely matched experimental findings.

Conclusions:

• The study validates the accuracy of the developed vehicle-track dynamic numerical model.
• Current safety standards for railway vehicles under seismic conditions appear conservative.
• A revised seismic early warning threshold of 0.04 g is recommended to enhance train operation safety during earthquakes.
• Further research into seismic wave spectrum characteristics is needed to fully understand their impact on vehicle safety.