- Investigation of differential movement at railroad bridge approaches through geotechnical instrumentation
- D. Mishra ; E. Tutumluer ; T.D. Stark ; J. Hyslip ; S. Chrismer ; M. Tomas
- Book Title / Journal: Journal of Zhejang University
- Year: 2012 , Volume: 13
- Keywords: Differential movement ; Bridges
- Railway transitions experience differential movements due to differences in track system stiffness, track damping characteristics, foundation type, ballast settlement from fouling and/or degradation, as well as fill and subgrade settlement. This differential movement is especially problematic for high speed rail infrastructure as the ‘bump’ at the transition is accentuated at high speeds. Identification of different factors contributing towards this differential movement, as well as development of design and maintenance strategies to mitigate the problem is imperative for the safe and economical operation of both freight and passenger rail networks. This paper presents the research framework and initial instrumentation details from an ongoing research effort at the University of Illinois at Urbana-Champaign. Three bridge approaches experiencing recurrent geometry problems were instrumented using multidepth deflectometers (MDDs) and strain gages to identify different factors contributing to the development
of differential movements.
- Evaluation of ground vibration induced by an urban train system
- Y.J. Chen ; Y-J Shen ; S-H Ni
- Book Title / Journal: IAEG2006
- Year: 2006
- Keywords: Vibration ; railroads ; environmental impact ; Environmental protection ; Bridges
- In recent years, more and more vibration sensitive buildings are located near the planned route of urban train systems, thus the ground vibrations induced by train systems have drawn engineer's interest. In previous research this area has focused on the vibration characteristics and mitigation methods. Research on these two subjects has progressed well. However, the evaluation methods for the train-induced vibration among current assessments present obvious differences.
The main purpose of this research is to examine these evaluation methods using field measured data. The evaluation methods from different available representative assessments are reviewed briefly, and then a series of field vibration measurements of urban train systems were compared with these evaluation methods.
For the site vibration measurement, the three-dimensional Tokyo Sokushin Model 15D servo-type velocity transducer will be used to measure the velocity level of vibration. The sampling frequency used for time domain data is 512 Hz. The HP 3565S Vista system is mainly used to collect the data and to analyze the dynamic signals. The frequency response is presented using one-third octave band for the central frequency ranged from 1 to 100 Hz.
The measurements include a wide variety of soil and structure conditions. The main vibration sources include rapid transit system and ordinary railway system with different speeds on different train supporting structures, such as on concrete or steel bridges. A broad base of geological conditions (including soil, gravel and rock) and foundation types such as spread footing and pile foundation are used for this evaluation. These
various conditions present different vibration characteristics. Based on this evaluation, the suitability of each vibration assessment method is presented and some recommendations for further studies are proposed.