ABSTRACT
The inertia force ratio ri is a product of the inertial mass and the angular acceleration, and the ratio of force in the model and the prototype is shown by following Equation:
r I Ii m m
⋅
⋅
θ θ
(1)
1 INTRODUCTION
Drill rigs (hereinafter referred to as the machinery) are mainly used for the foundation work of highrise buildings and ground improvement. A photograph of at drill rig is shown in Figure 1. This machinery is frequently used in urban areas. Recently, there have been accidents in which this machinery has toppled over. In cases where the machinery topples, the risk to the lives of workers is not the only problem as this can also block trunk roads etc., causing great problems for society at large. There are two factors to the toppling of machinery. One factor is structural instability stemming from a high centre of gravity, and the other factor is the ground where the machinery is set up being too soft.
