Cavities are found many times recently in downtown of metropolitan cities due to old and damaged pipes installed in the ground. The cavities are generated by spilling out of water from pipes mostly. The cavities generated below subway track can make irregularities and instability of the track. In this study, a finite element program ABAQUS is used to analyze the structural behavior of the track in cases of existence of cavities in subway trackbed foundation. It is found from the FE analysis that there can be a lot of differences in displacement of the track, depending on soil modulus, depth and diameter of cavity. The most important influence factors on the structural stability of track can be provided from the analysis in case of cavity existence in the trackbed foundation. Influence index is proposed in this study for design purpose by investigating geometrical cavity location in the ground that is to be used for checking stability of railway track.

cavity; FEA; subway; trackbed stability; influence factor