Vertical Earth Loads on Buried Engineered Works

Abstract

The theory of vertical earth loads on buried engineered works is extended with a closed‐form solution to include ditch geometries with backslopes and wide ditch bottoms, as well as works buried under fills. A variable horizontal stress ratio that is a function of the backslope angle is proposed to accurately model the effects of the minor principal stress arch. Parametric studies of the effect of ditch slope, ditch‐bottom width, and friction angle upon the vertical earth load are explained. Without including the effects of sloped ditch geometries, the vertical soil load may be underestimated. The theory is applied to narrow underditches as a means to lessen earth load. The theory explains full‐scale experimental observations and is readily broadened to include positive projecting structures buried in fills. An iterative design procedure is suggested for structures that are buried under fills, incorporating the minor principal stress arch and structural stiffness. Ditch geometry is an important construction control for both slope safety and the estimation of the load on buried works; these two constraints must be optimized in design.