A Study Of The Validity Of Slope Stability Analysis With Strength Reduction FEM

Since 1970s,the theory of strength reduction technique has been developed, many researchers have made contributions to it in different aspects. The purpose of this paper is to study validity of the strength reduction FEM in slope stability analysis. In recent years, with the development of FEM and computation methods, the study and use of strength reduction technology in slope stability analysis becomes popular more and more. But, all the researchers studied were homogeneous slopes, were comparisons of safety factors from strength reduction between those from other methods, in order to prove strength reduction, the scientificalness and validity of strength reduction has never been rigorously proved, although it was firstly suggested by some famous experts and has been used more and more widely. In order to analyze the validity of strength reduction FEM in slope stability analysis, to make it free from being used inappropriately, for the first time this paper had made an exam and criticized the technique within an entirely scope.Firstly, the correctness of strength reduction FEM was discussed in the point of view of conception, so its disadvantages are outlined in different aspects: stress fields, failure rules, its feasibility and scientificalness, influences of various parameters, etc.Beening different from all the studies before were all within the scope of homogeneous slopes, in this paper, various types of slopes were analyzed by using a modified FEM program, with Duncan-Chang's model. Then, the stress fields, critical slip surface and safety factor before and after strength reduction were compared in order to analyze the feasibility of strength reduction FEM for homogeneous, non-homogeneous (multilayer, especially those with weak layers) slopes and those with retaining structures.Through the calculation and analyses, it is found that, for homogeneous slopes, the stress fields have already been changed, so other relevant results are of little significance, even though safety factors could be got; but for non-homogeneous slopes, there is no definitude or valid reduction way for multi-material slopes, both the stress fields and displacement fields are changed with the same reduction parameter, so neither the safety factor nor the stress field is valid.