EFFECTS OF PARTICLE SIZE DISTRIBUTIONS AND PRINCIPAL STRESS AXIS ROTATION ON CYCLIC PLASTIC DEFORMATION CHARACTERISTICS OF COARSE MATERIALS

Biyanvilage Dareeju ； Chaminda Gallage ； Tatsuya Ishikawa ； Manika Dhanasekar ； Les Dawes

《Journal of GeoEngineering》 13卷4期 (2018/12) Pp. 166-170

https://doi.org/10.6310/jog.201812_13(4).1

摘要

Cumulative plastic deformation characteristics of rail tracks under moving wheel loads are complex problems. Globally the rail industry is challenged by effective maintenance strategies to ensure safety of the rail track structures. Influence of particle size distributions (PSDs) on the cyclic cumulative plastic deformation of coarse materials in the rail track substructure layers under moving wheel load is not well understood. Conventional test approaches, namely the direct shear test, the cyclic single point load test, and the California bearing ratio test, cannot replicate the actual stress-strain state of coarse materials under moving wheel loads. The multi-ring shear apparatus, an improved torsional simple shear apparatus to replicate moving train wheel loading conditions, was used in this study. The PSDs of coarse materials were experimentally simulated through modifications to the mass portions of different glass beads. The moving wheel loads introduce higher plastic deformation and lower resilient modulus irrespective of the PSDs compared to cyclic single point load tests. Further study with three natural coarse materials (Toyoura sand and two ballast types) indicates that the cumulative plastic deformation has nonlinear relationships between the principal stress axis rotation and PSDs of the materials.

關鍵字

Particle size distribution ； cumulative plastic deformation ； multi-ring shear apparatus ； moving wheel load ； glass bead