Bearing capacity of low-density volcanic rocks using the discontinuity layout optimization method

The failure criterion of low-density volcanic rocks differs radically from that of conventional rocks by manifesting collapse under isotropic stress. In this way, the shapes of the failure model do not reveal a continuously increasing growth of deviating stress with the isotropic stress, but they reach a maximum value after which they decrease until they vanish for the isotropic collapse pressure. As a consequence, engineering applications require the implementation of numerical codes and the resolution of associated numerical difficulties. This article presents the problem of the bearing capacity of a foundation on a low-density volcanic rock using the DLO (Discontinuity Layout Optimization) numerical method. The analysis of results shows the ability of the DLO method to solve the numerical difficulties associated with the complex failure criteria so that the convergence and stability of the solution can be achieved without generating high computational costs. Additionally, a discussion of the DLO results is also carried out, obtaining forms of failure on the ground following the real collapses in these volcanic materials. The bearing capacity values of the numerical analysis are also analyzed and compared with the expected values in this type of rock, resulting in a satisfactory comparison of results. In this way, an adequate and reliable resolution technique is provided to face the problem of bearing capacity in low-density volcanic rocks, overcoming limitations referred to in the technical literature regarding the difficulty of treating highly non-linear and non-monotonic numerical criteria, and that allows the introduction of isotropic collapse failure.