CHARACTERSTICS OF THE SOFT GROUND ROADBED OF RAILWAY UNDER DYNAMIC LOADING CONDITION

초록

Ballast and roadbed are the structure damaged gradually by the repeated train loads, thus continuous maintenance work is required. Traditionally, ballast and roadbed are maintained by the empirical approaches; however, systematic researches have been carried out on the track deflection and the development of protective measures to minimize the maintenance cost. The use of roadbed for elapsed time period produces generation of fine grains from wear of ballast, ballast settlement due to the lack of the bearing capacity of the subgrade, and subgrade softening and mud pumping caused by the thaw and freeze during winter. In this study, influence of water and loads on the softening of subgrade is investigated from model tests adopting various wheel loads and travel passing velocity conditions, and from the test results, occurrence of mud pumping under repeated loading condition, settlement of ballast into subgrade, and vertical earth pressure are examined.