Resistance law of a rod penetrating a multilayer granular raft

Abstract

This paper presents an experimental study on the resistance law of a rod vertically penetrating different kinds of multilayer granular rafts with a constant velocity so as to reveal the mechanical properties of the multilayer granular rafts. The resistance was quasi-static under the chosen velocity. Experiments were conducted with different granular thicknesses, rod diameters and combinations of particles and liquids. The study shows that the resistance-displacement relation of the rod has three smooth stages. In the first stage, the resistance rapidly increased. In the second stage, the resistance curve maintained an almost constant slope. In the third stage, the resistance smoothly changed with its slope continuously increasing. Based on the corresponding physical models for each stage, the study reveals the exponential dependence of the load-bearing capacity of the multilayer granular raft on its thickness, and clarifies the capillary effects on the resistance law. The study extends the knowledge of the granular raft from monolayer to multilayer structure.

A pressure-sensitive rheological origin of high friction angles of granular matter observed in NASA–MGM project

“…( 1), it is assumed that the granular material with no cohesion follows the Mohr-Coulomb strength criterion, which is literally the friction law of deformable materials in terms of normal and shear stresses. [10] In contrast, conventional friction law of rigid materials is defined in terms of normal and frictional forces. The peak and critical friction angles of Ottawa sand are calculated by submitting the peak and critical state axial and confining pressure listed in Table S1 of supporting information into Eq.…”