挡土墙背摩擦角为负的被动土压力研究

目前大多数被动土压力问题研究的是挡土墙背摩擦角为正的情况(墙身相对土体向下移动)，而挡土墙背摩擦角为负(墙身相对土体向上移动)的被动土压力问题则研究的较少。在平面滑裂面假设的基础上，利用散粒体Kötter方程通过极限平衡分析得到了挡土墙背摩擦角为负时的被动土压力系数、被动土压力合力和被动土压力合力作用点高度的理论公式。分析了挡土墙倾角、填土内摩擦角、填土坡角和墙背摩擦角对被动土压力系数、土压力合力作用点高度的影响。与挡土墙背摩擦角为正不同的是，墙背摩擦角为负时随摩擦角的增加，被动土压力系数减小。用图形和表格的形式给出了相应的结果，可为锚、输电线路基础受上拔荷载时设计所采用。

Study on passive earth pressure for negative wall friction angle

Most of the earlier analyses of passive earth pressures behind retaining walls dealt with the case of positive wall friction angles(the wall moves downwards relative to the backfill), while the search on passive earth pressures for the negative wall friction angle case (the wall moves upwards relative to the backfill)is still lacking. Based on planar rupture surfaces hypothesis, the theoretical formula of the passive earth pressure coefficient, the resultant force of earth pressure and the application point of the resultant has been obtained using the Kötter equation with limit equilibrium method of analysis for the negative wall friction angle case. The effect of variation in wall batter angles, ground slope, wall friction angle and soil friction angle on the passive earth pressure coefficient, the application point of the resultant are considered in the analysis. It is not similar to the positive wall friction angle case, the passive earth pressure coefficients decrease as the wall friction angle increase in the negative wall friction angle case. The results are presented in graphical and tabular formats which can be served for anchor and transmission line foundation under uplift loading.