Ultimate Bearing Capacity of Low-Density Volcanic Pyroclasts: Application to Shallow Foundations

The present research focuses on the calculation of the bearing capacity of low-density volcanic Pyroclasts. First, the theoretical basis that define an adequate failure criterion for collapsible rocks based on the parameters that characterize them are developed here. Second, a mathematical characteristic lines method is proposed to resolve the ultimate load of shallow foundation rocks with collapsible failure criterion. This method leads to an analytical solution that differentiates two possible rupture mechanisms depending on the rock parameters and external confining load: (a) plastic failure wedge; (b) failure due to destructuring. The analytical solution is also represented in design abacuses to make it easy and quick. Finally, the proposed formulation is validated using numerical models by implementing the collapse criterion as a model defined by the user in a finite difference code. The result is a satisfactory comparison of bearing capacity values and the analytical rupture mechanisms.