土钉-排桩复合结构的软土主动土压力分析

ANALYSIS ON ACTIVE EARTH PRESSURE OF SOFT SOIL IN NAIL-ROW PILE COMPOSITE RETAINING SYSTEM

在土钉-排桩复合结构中,土钉的加固机理使软土主动土压力减小,而土钉的锚拉作用又可能使软土产生附加侧压力。综合土钉这2个相反效应,建立了一种基于结构位移推算土钉复合结构上软土主动土压力的方法,即引入实际破裂角概念,位移量决定实际破裂角的大小,通过实际破裂角推算软土主动土压力,并将这一分析方法试用于某工程的围护稳定性动态评估中。

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.