2006 年 55 巻 5 号 p. 452-457
Scaled analogue model experiments are an excellent technique to examine underground geometry of geologic structures and its development processes, thus have been widely applied to the petroleum exploration. The experimental results are strongly affected by the physical properties of the materials, thus this paper measured the grain size and the internal friction angle of popular granular materials and compared them with the model results by a series of shortening experiments. The shear-box-test results showed that micro glass beads have a smaller internal friction angle than that of sand grains, and the grain size has little effect on the internal friction angle of micro beads. The results of the analogue experiments suggested that the internal friction angle defined by the grain shape affected the thrust fault angle as well as the surface inclination of the uplifted wedge-shaped structure. The material of a higher friction angle extended the fault spacing and increased the displacement of each fault. The grain size of the material has an effect of strain localization, and the number of faults was increased in the experiments of smaller grains.