Failure Mechanisms in Jointed Rock Slopes Concerning the Dip Angle of Continuous Joints

Abstract

ABSTRACT: Jointed rock slopes surround critical infrastructure and communities, such as dams, roads, tunnels, bridges, mines, and buildings. The mechanical behavior of jointed rock masses depends on the complex interactions between joints, rock matrix, boundary conditions, and loading states. When a jointed rock mass undergoes environmental stressors, the generated tensile and shear cracks through intact rock blocks and pre-existing discontinuities determine the mechanisms and implications of the consequent slope failure. However, predicting fracture evolution, corresponding stress transfer mechanisms, and consequent failure states are challenging due to the complex interactions between the slopes' structural components. This study aims to understand the effects of such interactions on the overall response of slopes concerning the dip angle of continuous natural fractures when a local failure is triggered in fractures close to the slope face. This study employs the combined finite discrete element method (FDEM) to examine the slopes' mechanical response, including the progressive failure mechanisms. The results of this quantitative analysis are processed and visualized through graphical representations depicting the distinct failure modes observed in jointed rock slopes with various dip angles. 1 INTRODUCTION Failure of rock slopes ranks among the most dangerous geological hazards, causing yearly fatalities, significant disruptions to infrastructure, environmental challenges, and adverse socioeconomic impacts. Thus, it is crucial to detect the early signs of failure by understanding the mechanisms that drive new fractures, activate pre-existing fractures, and finally cause a global failure. Failure of rock slopes occurs for various reasons that contribute to either an increase in shear stresses applied on the slope or a decrease in the shear strength of the rock mass. The latter may happen due to weathering, water infiltration, and anthropogenic activities. Studies show that the impact of shear strength reduction on the failure mechanism of jointed rock slopes depends on factors like joint or discrete fracture network (DFN) density (Wang et al., 2003), roughness (Ban et al., 2020, Rullière et al., 2020) and orientation of the joints (Bahaaddini et al.,2013), the properties of the infill material within the joints (Jiang et al., 2015), the degree of saturation of the infill (Indraratna et al., 2014), and the average normal stress acting on the joints (Mišcˇević et al., 2014). The arrangement of fractures within a rock mass can also determine the potential for block detachment, toppling, and sliding. Highly connected fracture networks can delineate potential sliding or toppling blocks, significantly influencing slope stability (Romer & Ferentinou, 2019).