Physics of building vulnerability to debris flows, floods and earth flows

Abstract

Mass flows such as landslides and floods pose great risks to the built environment. In the literature the assessment of the building vulnerability to these different mass flows is evaluated separately and little effort has been made to investigate the interaction mechanisms between mass flows and buildings, leading to a lack of explicit failure mechanisms in many vulnerability models. In this study, the failure modes of a typical reinforced concrete building upon impact by debris flows, debris floods, floods and earth flows are discovered through an explicit finite element platform LS-DYNA. Five impact cases with increasing solid concentration; namely, low-intensity water flow, high-intensity water flow, debris flood, debris flow and earth flow, are considered. The intrinsic physics of building damage by these flow-like mass movements is compared. The frontal walls and side walls are vulnerable to any type of flow. A forward pushover failure mode, which is a global failure of the building frame, is observed in the high-intensity water flow and debris flood cases. Upon impact by an earth flow, progressive local failure of the columns at the ground floor can occur and lead to backward collapse of the building. Upon impact by a debris flow, both the local column failure and the global pushover collapse of building can occur, as debris flows with high solid contents are an intermediate flow sharing characteristics of both floods and earth flows. The in-depth study of the physics of building damage provides a solid basis to develop generic vulnerability models for such flow-like mass movements of varying solid contents.