Influence of moving wheel loads on mechanical behavior of submerged granular roadbed

This paper presents an experimental study to evaluate the synergistic effects of principal stress axis rotation and change in water content on the mechanical behavior of granular roadbed subjected to cyclic moving wheel loads. Two types of small scale model tests and laboratory element tests, in which a single-point loading method and a moving-wheel loading method were adopted, were mainly performed with a base course material under air-dried condition and saturated condition. Based on the test results, the applicability of a multi-ring shear test, which is a torsional simple shear test, to an element test of granular base course materials subjected to moving wheel loads, and the influence of water content and moving-wheel loads on the deformation–strength characteristics of granular roadbed were examined. The results indicate that the multi-ring shear test has excellent applicability to the estimation of deformation behavior of granular base course materials subjected to repeated moving-wheel loads. Besides, it was revealed that residual settlement of submerged granular roadbed is more likely to increase with the repetition of moving-wheel loads than that of air-dried one and under single-point loading, showing that the difference in the loading method and water content has a considerable influence on the cyclic plastic deformation of granular roadbed. These lead to the conclusion that for the precise prediction of the long-term performance of granular roadbed under cyclic moving-wheel loads, it is important to take into account the synergistic effects of principal stress axis rotation and change in water content on the cyclic plastic deformation characteristics of granular base course materials.