Arching for Vertically Buried Prismatic Structures

The problem of defining the load carried by a prismatic structure buried vertically in soil at the surface of which is applied a uniform static pressure of infinite extent is investigated. Based on certain simplifying assumptions, a general solution is obtained in terms of the geometry of the problem and the properties of the structure and soil. Both the case of a floating structure and a structure mounted on a rigid base are considered. The solution is based on an analogy to the elasticity problem of a rigid die pressed into an infinite elastic half space and thus assumes that no failure of the medium occurs. Definition of the stress or strain distributions either in the structure or in the surrounding medium is not attempted. The results of numerous experiments with right-circular cylinders in dense 20-30 Ottawa sand are presented which tend to confirm the theory except when the cylinders are long and rigid, in which case failure of the sand is likely to occur. The conclusions reached are directly applicable to the design of small stress and strain gages for use in dense sand and should also be useful in estimating the axial load carried by a structure of any size buried in soil.