Vu Thanh Ngo, Jaehak Park, Seongbaek Park and Yujin Lim
International Journal of Railway, vol. 9, no. 2, pp.46-49, 2016

Abstract : In this study a new detection technique based on WAK is introduced that can be used for identifying unstable con-crete sleeper installed in ballast by triggering activated wave on the sleeper surface. If a gap exists immediatelybelow the concrete sleeper, static stiffness can be lower than stable case’s stiffness. The concrete sleeper isassumed as a single degree of freedom system (SDOF). The static stiffness K can be obtained by iteratively calcu-lated mass (m), stiffness (k) and damping coefficient (c) of SDOF system. Those coefficients are used to specifythe ballast condition such as a gap between the sleeper and ballast. Typical test results using a small sleeper modeltest are summarized and explained for proof of effectiveness of the WAK test for checking unstable condition ofthe sleeper.

Keyword : Track, Track stiffness, Gap, WAK, Nondestructive test