Abstract:Soil-nail and the grouting materials enhance continuity of soft soil along soil-nail,and soil-nailed soft soil has lower active earth pressure. The nail-row pile composite retaining system preserves the above characters. The row pile will pull soft soil outside through nail when the system displacement is large. These opposite effects may lead to additional lateral pressure and make active earth pressure of soft soil bigger than the theoretical value. Based on the above analysis,the paper suggests a new calculation method of active earth pressure of soft soil according to the displacement of nail-row pile composite retaining system. The relation between system displacement and real rupture angle of soil is established to calculate real active earth pressure with the help of classical equation. Considering soft soil being harden by soil-nails,the paper makes active earth pressure discounted,and discount coefficient is related to system displacement. The analysis result is tested in the stability evaluation of a retaining structure of foundation pit.