考虑渗流作用的土坡稳定分析Fellenius法和简化Bishop法

FELLENIUS METHOD AND SIMPLIFIED BISHOP METHOD FOR SLOPE STABILITY ANALYSIS CONSIDERING SEEPAGE EFFECT

通过对土条进行严格的力平衡分析,论证了土条浸润线下等体积水的重力与外表面水压力的合力为渗透力。由此得出土坡稳定分析中正确考虑渗流作用的方式是:当以水土混合体为研究对象时,应考虑土体周围孔隙水压力而不考虑渗透力;以土骨架为研究对象时,应考虑渗透力而不考虑孔隙水压力;用孔隙水压力分析时须与土体饱和重度相对应,用渗透力分析时须与土体浮重度相对应。将均质各向同性土体的稳定渗流场中流线简化为平行于浸润线的直线簇,分别将水土组合体和土骨架作为研究对象,经严格的力学分析和数学推导,得到渗流作用下经典土坡稳定分析方法中Fellenius法和简化Bishop法的安全系数求解式,对所得的安全系数计算式的对比分析可知,两种方法在本质上是一致的。采用该文方法的实例计算结果与严格条分法的计算结果的对比表明:考虑渗流作用的Fellenius法和简化Bishop法在滑坡分析中是可行的。

Through strict balance analysis of the forces acting on soil slices,it was proved that the resultant composed by gravity of water with same volume of soil under the phreatic line and pore water pressure acting on the surface of soil was seepage force.The influence of seepage on the stability of soil slope should be considered properly.It was suggested that the pore water pressure around the soil mass not seepage force should be taken into account when the subject was the mixture of soil and water and vice versa when the subject was soil skeleton.The pore water pressure should be in balance with the soil saturated unit weight and the seepage force should be in balance with the soil buoyant unit weight.In steady seepage,the flow line was simplified as straight line paralleled to slope surface.Taking the soilwater combinations and soil skeleton as analysis object respectively,the formulas of safety factor in seepage soil mass for classical slope stability methods such as Fellenius method and simplified Bishop method were derived after the mechanical analysis and mathematical calculation.Comparing the safety factor formulas of the two subjects,the same results were obtained and the results indicated that the two methods were the same in essence.These methods were proved to be reliable because the safety factors of the methods were consistent with the results of strict slice method.