This study estimates the maximum impact force for a rock-shed slab in a rockfall. A discrete element program is calibrated using small-scale physical experiments and is then used to model the movement for a large scale rock-fall and to measure the impact forces. The results from the small-scale experiments show that the maximum impact forces are significantly affected by the mass of the rock-fall, the height from which the rock falls and the falling process. The full-scale numerical modeling for a field case confirms these experimental results and demonstrates the effect of rock-fall modes and the contact stiffness between the rock and the rock-shed. This study provides guidelines for the design of rock-shed structures where there are large rock-fall problems.本文主要利用數值模擬評估大規模落石之最大衝擊力，藉此作為國內明隧道頂板結構設計之參考。而數值模擬主要採用分離元素法，經由物理模型試驗進行比對驗證後，進行大規模落石運動過程模擬與衝擊力量測。物理模型試驗結果顯示，落石引致之最大衝擊力主要由落石量、落距與崩落過程等因素影響最為顯著。由全尺度數值模擬結果顯示，其除可滿足物理模型之落石衝擊行為外，對於崩落型式、落石材料與明隧道頂板間之接觸勁度亦可量化出其影響特性，故對於明隧道頂板設計或陡坡危岩處理考量上，應可最為後續研究與工程防護設計之參考
