Mechanism analysis of stability of cut-and-fill roadbed interface

The influence factors of the interface on the cut-and-fill roadbed are studied; and reducing these to two kinds as a whole, geometrical features and physico-mechanical parameters. The characteristics of interface step and the discrepancy of the filling physico-mechanical parameters are researched; and it is indicated that there are limitations in the imbalanced thrust method, such as in plotting slices and there is error in the count result. So the author illuminates that the imbalanced thrust method is unsuitable to be used in analyzing the stability of cut-and-fill roadbed basing on interface. And the MSarma method which is developed freshly to replace the imbalanced thrust method is recommended. Based on mass of cut-and-fill roadbed interfaces in a highway and combining the orthogonal design, statistic method and MSarma method, the mechanical mechanism analytical method for analyzing the stability of cut-and-fill roadbed interface is formed. This method is used to analyse the stability of cut-and-fill roadbed interface in three different cases; and the sensitivity priority of each factor to stability coefficient of roadbed is also given; the rank top 4 are cohesive force, internal friction angle, interface and roadbed obliquity; and then the selecting principle of filling, interface parameters and the form of roadbed is advanced, which is based on the study of the quantity relation between the four parameters and stability coefficient and comparing the variety trend.