Small-scale Geotechnical Testing Using a Six-axis Robot

Abstract

Single-gravity (1-g) small-scale testing is a widely used method to investigate geomechanics problems that involve the interactions between soils and objects (e.g., structures or machine parts). This letter presents a new approach for performing 1-g model tests where a six-axis industrial robot functions as a versatile actuator capable of moving objects along virtually arbitrary trajectories, while simultaneously tracking multiple components of force and moment acting on the objects. A performance evaluation confirms that the robot's motion control and force measurement are sufficiently accurate for geotechnical model tests. This assessment is completed through two benchmarking exercises: (1) determining the failure envelope of a strip foundation subjected to combined loading and (2) quantifying the force-displacement history for the soil cutting process (e.g., for applications in soil-machine interaction).

Efficacy of simple continuum models for diverse granular intrusions

“…Both of these studies observed increasing drag force fluctuations with an increasing initial packing fraction of the granular beds. Similar force fluctuations were observed by Kashizadeh and Hambleton 63 on reduced-order modeling of the plowing processes in sands and by Jin et al 64 in the development of a new single-gravity (1-g) small scale testing methodology. As this phenomenon directly relates to the changing density of the media, we use the more detailed DPM model for this case.…”