Torsional displacements and stresses in non-homogeneous soil

A study is presented of the axially symmetric deformation of a non-homogeneous elastic halfspace subjected to torsional shear tractions that are linearly distributed over a circular portion of the otherwise free surface. The problem is formulated in terms of Hankel integral transforms and an inverse procedure is implemented in which the determination of the type of non-homogeneity constitutes part of the problem. A numerical parametric study shows the effect of the degree of soil inhomogeneity on the distribution of circumferential displacements and shear stresses in the medium. With increasing non-homogeneity stresses affect soil at greater vertical and lesser radial distances. Gibson’s law of the Winkler-type behaviour of linearly inhomogeneous, incompressible soils can only qualitatively apply in this case, as the surface displacements tend to become proportional to the applied local pressure and decay rapidly away from the torsionally loaded area in strongly non-homogeneous deposits.