Mechanical Behavior of Earthen Materials in Structural Applications

Soil has been used for millennia as a structural material due to its widespread availability, cost, ease of construction, and utility in creating durable, comfortable structures. Modern engineers are reexamining this material in part for the practicality and economy, especially in developing regions of the world; however, it has also attracted interest due to its sustainability. The material has low embodied energy and high thermal mass, and can often be sourced locally. Less attention has been paid to these materials structurally, though, compared to steel and concrete. In this paper, we create a finite element analysis of an earthen structural wall under shear loading. The earthen material behavior is fit to a complex plasticity model for geomaterials that incorporates a smooth tensile-shear failure surface, kinematic hardening, and other features. Localized failure is measured by a loss of ellipticity condition, and post-failure softening modeled with an enhanced strain finite element. These elements include additional internal degrees of freedom to track opening and shear displacement on a surface inserted at the most critical orientation when the failure is detected. The model is used to capture the failure response of structures. In particular, the effect of the weak interfaces is examined.