Abstract
To optimize concrete tracks in terms of reasonable loading structure, superior workability, easy maintenance and economic efficiency, a new solid-bed track with resilient sleepers has been developed by the authors. In this research, to clarify the shrinkage behavior of this track, full-scale track members were prepared. To investigate the shrinkage behavior of the track, numerical simulation was performed using a three-dimensional multi-scale coupled model where the microscopic characteristics of cementitious composites and nonlinear structural mechanics are integrated.
The results of this study indicate that shrinkage cracks can be generated from just under the corner of sleepers in an inverted V shape when the thickness of the track is relatively thin, on the order of 80 mm. However, generation of shrinkage cracks can be restricted when the thickness of the track is greater than about 280 mm, as is typical in snowy cold regions. The results indicated also that the generation of shrinkage cracks is unlikely when the thickness of the track is about 580 mm. This may be due to the fact that the age at which the main stress peaks is delayed as development of shrinkage behavior slows down when the thickness of the track is large, and therefore the tensile strength of the concrete increases with age. Another reason might be that the restraining effect of the concrete bed of the track is small when the thickness of the track is large.
In addition, to control the propagation of shrinkage cracks, the position and size of crack induced joints were investigated. Based on the numerical simulation results, it was found that shrinkage cracks can be vertically generated when the sectional defect range is set to about 10%.
