Moving Step-Load on Half-Space of Granular Material

The plane strain problem of a step load, p, moving on the surface of a half-space of granular material that is governed by internal friction of the Coulomb type, is studied. The material considered is postulated to be incompressible during slip, that is, it does not exhibit dilatancy. As a first step toward a more complete solution, it is assumed that in regions of slip the elastic portion of the deformations may be neglected versus those resulting from slip. The assumption permits closed form solutions, but limits the validity of the results to Mach numbers of less than approximately 0.20. The study indicates that for values of p exceeding a limit depending on cohesion, granular particles will be expelled at the surface ahead of the pressure front. The applied pulse will thus be preceded by a precursor of expelled grains.