Development in numerical modeling and evaluation of hazard for slope deformation and failure

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Rockfall and slope failure pose serious hazards to roads and facilities in regional areas. The aim of this study is to build a procedure to evaluate the zone at risk using numerical simulation. This paper reports numerical procedures for (1) rockfall and (2) progressive failure in slope.(1) This study has adopted a spring-dashpot-slider system to model the bouncing phenomenon, occurring when boulders impact on the slope. The normal and tangential components (R_<en>, R_<et>) of restitution coefficient are expressed using the micro-properties (k_n, k_t η_n, η_t) of the system and the kinetic conditions.A small-scale free-fall-rebound test using a sphere boulder in laboratory was conducted. The results show that R_<et> increase with the ncrease of the incoming angle and the newly developed program can capture the increase of R_<et>. Parametric mulations have been performed at different spatial resolutions using sets of synthetic biplanar slopes haracterized by mean inclination and local asperities. The influence of controlling factors on the dispersion of rockfall rajectory has been evaluated by conducting 3D simulation. Finally, a rockfall encounter analysis is proposed using he numerical method developed in this study.(2) A numerical modeling of progressive failure in slope using the distinct element analysis has been developed. The numerical modeling consists of two stages. The first is to get the mechanical properties of synthetic specimens omposed of circular rigid elements with the bonded effect between elements. The second is to analyze deformation of a reduced-scale rock slope under the gravity increased condition. With the calibrated properties of the synthetic specimen being unchanged, evolution of displacements and the resulting initiation of failure surface in the slope odel are displayed. The modeling can give a possible failure volume of rock slope based on the geometrical data and strength properties, such as cohesion and internal friction angle.