Continuous vertical Wheel-rail force Reconstruction method based on the distributed Acoustic sensing technology

Abstract

The vertical wheel-rail force is a direct reflection of the interaction between the wheel and rail. The continuous vertical wheel-rail force is not only of significance for ensuring the operation safety, but also provides precious information for the structure condition assessment. However, conventional measurement methods are incapable to meet the need for real-time condition monitoring over long distances. Therefore, this paper applied a newly developed optical sensing technology, the Distributed Acoustic Sensing (DAS), to the quantitative rail strain measurement. Taking full advantage of DAS, a Bidirectional Reconstruction Method (BRM) of the continuous vertical wheel-rail forces is proposed based on the swarm intelligence algorithm. This method was applied in the Beijing Metro and verified by comparison with the conventional Shear Force Method (SFM). The results show that the proposed method can ideally reconstruct the continuous vertical wheel-rail force and has potentials for the assessment of both track and vehicle conditions.