边坡稳定分析中关于不平衡推力法的讨论

不平衡推力法在我国工业与民用建筑及铁道部门广为应用,当边坡滑面为圆弧时,不平衡推力法的精度与严格条分法相当。然而,由于不平衡推力法假设条间合力的方向与相邻土条底面平行,从而导致在某些工况下(非圆弧滑面),安全系数的误差大到百分之几十甚至更大,这显然会给工程带来安全隐患。鉴于上述原因,以非圆弧滑面为研究对象,较为全面地分析了不平衡推力法在各种工况下(共200多个算例)可能引起的误差,得出误差最小的几种工况,并建议对于非圆弧滑面最好不要单独使用不平衡推力法,而应采取多种方法进行综合分析。

ON SLOPE STABILITY ANALYSIS BY IMBALANCE THRUST FORCE METHOD

Imbalance thrust force method (ITFM) has been used widely in the fields of industry,civil and railway in China. When the slip face is circle,the precision of ITFM is equivalent to that of rigorous method such as Morgenstern-Price method. But because the method unreasonably assums that the orientation of interslice resultant force is parallel to slice bases,for non-circle slips,the error of safety factor obtained from ITFM is up to several decades percent or more,which leads to hidden trouble inevitably. So,focusing on the non-circle slips,the error by ITFM in most kinds of conditions is analyzed thoroughly,and a few conditions with small error are obtained. For the analysis of slope stability,it is suggested that for non-circle slips,it is better not to use ITFM alone,but to adopt two or more methods,instead.