Figure 2. Experimental apparatus. (a) Plan view of experimental apparatus showing the two parts of the deformation table and computer-controlled stepper motors that drive each half. The model is constructed in the central part of the rig, and the sandpack is layered on top of baseplates having predetermined stepover geometries. (b) Stepover geometries analyzed in this article: 30° underlapping, 90° neutral, and 150° overlapping systems.