The effect of a soil mat is to reduce rock-fall energy and impact force. Although the construction costs for soil mats are low, these layers can substantially improve the margin of safety factor. This study examined the performance of a soil mat in reducing rock-fall energy using the discrete element method to investigate the transmission of the impact force in the granulated soil mat caused by rock-fall. The impact force received by a falling body (rock-fall impact force) and the impact force

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... ransmitted to the bottom (transmission impact force) due to rock-fall were investigated by examining the effects of particle properties such as hardness, size, and shape, and the soil mat characteristics such as the packing density and layer thickness on the peak impact force. The relationship between the time history of the impact force transmitted to the soil mats with different layer thicknesses and densities and the stress-strain distribution or energy dissipation in the soil mat was also discussed although the results reported here are restricted only to the case of vertical fall.