Rainfall infiltration and three-dimensional stability analyses of fractured rock slopes considering preferential flow

Rainfall infiltration is one of the main factors inducing landslides. For rock slopes with more developed fractures, the effect of preferential flow cannot be neglected. Thus, this study investigates the effect of preferential flow on the hydrological response and three-dimensional stability of fractured rock slopes under different rainfall conditions. A method combining the numerical solution of rainfall infiltration with the upper-bound theorem of the limit analysis kinematic approach is proposed. In this method, the internal dissipation rate by apparent cohesion in the energy rate balance equation of the three-dimensional rotational failure mechanism is calculated using the discrete summation technique. By considering a rainfall-infiltrated slope case, the infiltration law and hydrological response of the slope based on the dual-continuum model under four rainfall events were examined. Subsequently, the three-dimensional safety factor and failure pattern of the slope were analyzed. For comparison, the results based on the equivalent continuum model without considering preferential flow were also included. It was found that preferential flow can significantly strengthen the hydrological response and reduce the three-dimensional stability of fractured rock slopes. The current study presents a practical method for evaluating the hazard of fractured rock slopes subjected to rainfall infiltration.