本研究以振動台試驗為對象，建立土釘加勁邊坡動態數值模型，探討土釘陡坡受震之力學行為與加勁機制。與振動台試驗相同之模型的數值分析結果顯示，於地震尖峰加速度500gal以內數值模擬結果與試驗觀測值相近，確立本文所建立之動態土釘邊坡數值模式之適用性。此外，5倍坡高之後邊界距離為進行動態數值分析之適當邊界。另針對土釘傾角、土釘長度及土壤元素受震反應等因素進行探討，獲得陡坡土釘之最佳埋設角度，隨著邊坡坡度減緩而增大。若採用土釘最佳傾角配合最有效釘長(0.7倍坡高)，對抑制坡面變形有極佳效果；以坡度50陘岔銎Y為例，約可較水平土釘減少50%之坡面位移。受震期間土釘逐漸發揮抗張能力，經由土釘與土壤間之摩擦阻抗機制提供土壤圍束應力，降低加勁區內土壤元素之破壞勢能；位於加勁區外之土壤在受震時易產生降伏，尤其在入坡面方向之最大加速度時間點。而邊坡在強震來襲前若先受到一弱震作用，則能提高邊坡的抗震能力，降低該強震所產生的坡面位移。 results of shaking table model test conducted in the previous research revealed that soil nailing is effective in increasing the stability of steep slopes subjected to seismic load. However, comprehensive understanding of slope response regarding to the behavior of nails along with their length, stress distribution and development of failure mechanism in soil mass are difficult to obtain from model test. The numerical method can overcome the deficiency of the model tests and is employed in this study. A numerical model with finite difference program was developed. The predicted results were compared with those obtained from shaking table tests to validate the numerical model. A series of parametric study is carried out to investigate the effect of nail length and nail inclination on the nailed steep slopes behavior subjected to seismic loading. Research results show that: (1) The facing displacement of slope remains constant when the horizontal boundary greater than five times slope height is used. (2) The optimum nail inclination increases with the decrease of the slope angle. As compared to a horizontally reinforced slope, a 50?slope, reinforced with nails inclined to the horizontal at the optimum angle and using the most effective nail length, reduces the horizontal displacement by 50 percent. (3) The tensile force of nail is mobilized through the frictional mechanism between the nail and the soil mass during seismic load, the increase in confining stress reduces the failure potential for soil in the reinforced zone. (4) A mild seismic excitation prior to the strong seismic excitation reduces the displacement of the nailed slope.