Inelastic Wave Propagation in Soil Columns

This paper is devoted to both theoretical and experimental studies of the problems of one-dimensional waves in inelastic media such as soils. The fundamental problem involves the prediction of the stresses and particle velocities as functions of time and depth in a soil column when the pressure at the surface is known. In order to solve this problem, experiments were conducted to determine the dynamic stress-strain diagram of the material. The dynamic diagram is shown to differ appreciably from the static one at small relative densities (Dr 0.1 to 0.5) but only slightly at higher densities. In order to introduce this complex nonlinear and inelastic stress-strain relationship into the calculations, a theory has been developed using a step-by-step procedure. This one-dimensional method can take into account any type of stress-strain characteristics and all kinds of boundary conditions. Wave propagation experiments are shown in which the wave phenomena are observed and compared with the theoretical values. The agreement between measurement and calculation is satisfactory. Applications to underground shelter design are considered, and charts are developed for the rapid determination of inelastic wave effects for certain simple cases.