Application Of Intelligent Optimization Algorithms To The Soil Slope Stability Analysis

Soil slope stability analysis is involved in the geotechnic engineering and it is always performed by Limit equlibrium method, Limiting analysis and Fimite element strength reduction method. The limit equilibrium method plays an importmant role in the slope stability analysis due to its simplicity, although the numerical methods such as FEM have increasingly been adopted for the slope stability analysis. However, it is difficult to locate the critical slip surface while the LEM is used to perform the stability analysis of soil slope. Based on circular slip surface, the basic complex method is integrated with ant colony algorithm, particle swarm optimization method and simulated annealing method in order to determine the minimum factor of safety of complicated soil slopes. Based on non-circular slip surface, the basic harmony search method is improved and the procedure to generate new solution used in basic harmony search method is imported in the genetic algorithm. With the fast development of computer technique and a good many large optimization methods, the optimization methods are directly adopted to analyze the slope stability based on PanJiazhang extremum principle. The folowing eight chapters constitute the paper:In the first chapter, the significance of soil slope stability analysis and the merits and shortcomings are expounded, which leads to the necessity of the location of critical slip surface. Based on the existing problems, the objectives of this paper are put forward.The general program of slice methods is summarized and the potential slip surfaces including circular and non-circular slip surfaces are generated. The optimization function of the determination of critical slip surface is presented. The procedure to generate initial complexes is proposed and the concept of ratio of search optimum is given.In the third chapter, the existing basic complex method is improved in order to avoid its shortcoming. The procedure based on sort used to choose next point in basic ant colony algorithm is propsed and the mutation operator is imported into the standard particle swarm optimization method forming mutation particle swarm optimization method. Based on orthogonal tests, the computing parameters of ant colony algorithm, simulated annealing method are determined. The quasi-optima gotten by ant colony algorithm, mutation particle swarm optimization method and simulated annealing are used in the basic complex method. The proposed ant colony complex method, particle swarms complex method and simulatedannealing complex method are adopted to locate the circular critical slip surface of complicated soil slopes. The results show that the mixed complex methods are more likely to find the global minimum factor of safety than basic complex method.Baesd on the reasons for low global search ability of the basic complex method, the concept of diversity is put forward and three indexes such as resembility, resembling place and complex central place to measure the diversity of current complex are proposed. The diversity complex methods are presented. The computing results show that the diversity complex method using the index of resembility has stronger ability to find optimum than using the other two indexes. The complex method replacing redundant design point is presented by defining the redundant point as bad design point during iterations of basic complex method. The pseudo gradient is defined between one point and the centroid of the rest points. The point which has the maximum pseudo gradient and which contains more entrophy are adopted to generate the complex method based on maximum pseudo gradient and based on maximum entrophy. The three complex methods have stronger ablity to find global optimum than basic complex method for the same initial complex. The tabu procedure is integrated with the basic fish swarm method to avoid the iterance of search for the potential solutions forming tabu fish swarm algorithm. Before the use of basic complex method, all the design points are improved by simulated annealing with tabu procedure, the basic complex method continues after all the points are annealinged. The computing results by tabu fish swarm algorithm and tabu simulated annealing complex method shaow that the two new methods are much more likely to locate the critical slip surface than basic complex method.In the fifth chapter, the non-circular slip surfaces are generated connecting several points and the correcting strategy is substituted for the penalty strategy to correct the ifeasible general slip surface. The recently developed harmony algorithm is improved to search the critical non-circular slip surface. The search procedure used in harmony search method is imported in the genetic algorithm to produce new offsping forming genetic algorithm with harmony search procedure. The comparison of computing results with those existing results proves that the proposed correcting procedure and the modified harmony search method and the genetic algorithm with harmony search procedure are valid.Pan Jiazheng maximum extremum principle and minimum extremum principle are described by harmony search method and particle swarm optimization method in order to directly analyze the stability of soil slope using local factor of safety method. After one slice satisfies the limiting equilibrium condition, the procedure to tranfer redundant forces to the next slice is presented. The affect of two constraints about interslice forces on soil slope stability isstudied and the preferred constraint is pointed out. Based on the ergodicity of chaso variable, the chaos dynamic harmony search method is proposed and the results are promising.In the seventh chapter, the analysis of slope of nuozhadu's earth core rockfill dam is performed by the above methods.In the last chapter, the main achievements of this paper are summarized and the further research of this field is pointed out.