Abstract
Drill rigs are large pieces of construction machinery, used to build pile foundations and improve ground stability. In recent years, there have been several reports of accidents where drill rigs have toppled over. Two potential causes for these accidents are related to drill rigs becoming unstable. One cause is structural instability, where the body is composed of a top heavy weight distribution. The other is concerned with the supporting ground. During the construction process, rig sites are excavated and overlaid by reclaimed soil. These works produce uneven surfaces, as well as a distribution of different stiffnesses in the supporting ground. In this study, we first classify layout methods of a steel plate and conduct loading tests with several layout patterns while decreasing the acting pressure on the bearing ground through the crawlers. Secondly, a series of experimental simulations using a 1/25 scale model of a drill rig are performed in a centrifuge, in order to investigate the cause of drill rig instability with motion-image sequence analysis. Finally, we discuss the optimum layout methods of the steel plate.
