Based on the theory of the limit equilibrium method of slope stability analysis, this article studied the infinite slicing calculate theory under the circumstance that the loess slope sliding-plane does not cross the slope foot. Through the formula derivation, the analytic formula of the sliding torque Mr, and resisting moment Mf were calculated, and then it was concluded that the safety factor K is function of the smooth arc radius R, the sliding body string angle a and angle of slope plane distance Δl. We simplified the process of searching the most dangerous sliding surface on genetic evolution method reasonably and effectively. On the basis of concept of replication, hybridization, variation, competition and selection in biological genetic evolution steps, in the process of the most dangerous sliding surface search, change the two-way variation for one-way and increase mutant genes of the slope angle of plane distance. While other factors remain unchanged and only one of the factors changes, the minimum safety factor was computed under the restrictive condition and its applicability was determined. After changing another factor and repeating the searching process, the minimum safety factor and the corresponding value of various factors were figured out finally. Realizing search on the most dangerous sliding-plane does not cross slope foot. Also, we used FORTRAN software program to complete the compilation of the search procedures. The engineering examples have confirmed that this method is feasible and safe. This paper has important value of reference to improve the loess slope stability analysis theory.
At present, the theory of the limit equilibrium method is the main approach to analyse slope stability. However, it simplifies the boundary conditions of the landslide.
Different assumptions lead to various theory of limit equilibrium method of slope stability analysis.
The common theories are Bishop, Janbu, Spencer, Morgenstern-Prince and so on.
For various limit equilibrium methods stand for different hypothesis, they make remarkable effect on results and precision.
At the same time, these methods have complete and meticulous theoretical derivation. Because the methods themselves make some simplifying assumptions. Thus some unavoidable limitations and the final results are often different from the engineering practice, which may leads to low precision of results because we can only rely on the experience of slopes. In view of that, particularly on loess areas, it's eager to make an intensive study of each past theory to draw more precise limit equilibrium methods of slope stability analysis to guide the project. Moreover, it could reduce disasters of engineering to secure the safety of people's life and wealth.
