Colloquium #28

May 18, 2017 in

Monthly Railway Colloquium at TU Delft. Thursday May 18, 2017 the following researchers will present their work: Li Wang [Guest PhD] and Anthonie Boogaard and Pan Zhang [PhD’s at TU Delft].

Date:         Thursday May 18, 2017
Time:        4.00pm – 6.00pm [followed by drinks at PSOR]
Location:  Faculty of Civil Engineering and Geosciences [TU Delft]
Room:       CEG 2.62

Experimental study of the frequency-domain characteristics of ground vibrations caused by a high-speed train running on non-ballasted track
Li Wang [Guest Researcher at TU Delft]

An in-situ test to obtain vertical, transversal and longitudinal ground velocities and accelerations caused by high-speed trains was performed alongside the Chinese high-speed railway line between Beijing and Shanghai. The test results indicate that due to excellent track quality and consolidated infrastructure, regardless of the train speed below or above the Rayleigh wave speed, the dominant frequencies of both the vertical ground velocity and acceleration are integral multiples of the trainload frequency generated by the centre distance of two neighbouring cars. The frequency-domain distribution of the ground velocity is more sensitive to soil stiffness than is the ground acceleration; this is especially the case for the first dominant frequency. Whether the frequency amplitudes of the vertical ground vibration are higher than the horizontal vibrations depends on the soil stiffness. The greater is the soil stiffness, the higher is the frequency-range of the vertical ground vibration compared with that for the horizontal vibration, and the smaller is the difference between the three-dimensional frequency-weighted ground vibration level and the vertical vibration. Thus, effects of horizontal ground vibrations cannot be ignored when the foundation soil is soft.

Comparison between wayside and train-borne monitoring using acceleration measurements
Anthonie Boogaard [PhD Researcher at TU Delft]

Vibration based condition monitoring is a useful technique to assess the state of system based on its dynamic behaviour. This technique is also very suitable for monitoring track structures and has already been used successfully to detect defects on the railhead by measuring the accelerations of the axle boxes. This Axle Box Acceleration (ABA) system can also be used to monitor the state of specific rail components like insulated joints and turnouts.

During this presentation ABA data from a crossing will be presented and compared with data obtained using a wayside monitoring system. By measuring these acceleration simultaneously, the applicability and limitations of the ABA system for monitoring rail components can be derived.

Test and Modelling of fastening rail pad
Pan Zhang [PhD Researcher at TU Delft]

Rail pads are one of the main components of track structure, placing between the rail and the sleeper. Their function is to transfer the rail load to the sleeper while filtering the high frequency force. This resilient material plays an important role in track dynamic behaviour. Track deterioration such as short pitch corrugation and squat depends strongly on the condition of rail pads. Therefore, obtaining accurate dynamic parameters and choosing appropriate constitutive model of rail pads are fundamental demand for track design and reduction of track degradation.