Research On Critical Slip Surface Search Technology And Strengthening Optimization Of Loess Slope

China is a country that frequently suffers from landslide disasters, especially in the loess region. This is caused by its large scale, complex mechanism and huge damages. Consequently, a thorough determining the slip surface and understanding the behavior of landslide is essential for engineering. However, the workload of existing search methods of critical slip surface is so bigger, and even some methods is easy to fall into the trap of local minimum in the calculation process, which obviously doesn’t ensure the accuracy of the critical slip surface. In order to solve above-mentioned problems, based on the principle of coordinate alternation method and variable metric method, an alternating variable metric method is developed to explore the search method for critical sliding surface in any shape. And also, a combination of this method and finite element strength reduction method can improve greatly the efficiency of the searching sliding surface under the conditions of its accuracy. In addition, this paper has optimized reinforcement measures for this slope. The main contents of this paper are shown as follows:(1) The existing problems of strength reduction methods and the determination criterion of slope instability have been elaborated detailed. Based on the theoretical and actual examples analysis, the effect of elastic modulus(E) and Poisson’s ratio(μ) on the sensitivity of finite element strength reduction method was investigated.(2) A combination of variable metric method application program by using MATLAB code and finite element strength reduction method is used to search the critical sliding surface of side slope of oil unloading station in northern Shanxi. In addition, Comparing with the results of field data, the feasibility and practicability of this method are verified.(3) Because the geological structure of oil unloading station in northern Shanxi is complex. In order to effectively simulate the working mechanism of anti-slide pile, a series of 3D numerical models was simulated using a finite element code, ABAQUS. In view of the existing problems in the design of anti-slide pile, the effect of row spacing, pile spacing, cross-sectional dimensions of pile was considered to investigate the strengthening and optimization mechanics for slope. This study can provide useful reference for the design of complex anti-slide pile for the future work.