Slope Stability Analysis Of The Most Dangerous Slip Surface Search

Slope problems have always received extensive attention by many researchers. Slope stability is very important problem on civil engineering construction of the digging deep foundation of expressway, railway, airfield, and high-rise building, etc. The excavation for slope has received hundreds of meters deep. Whether the results of slope stability are right or not is related with the result of slope engineering and even endangering the safety of people's life and property. Slice method is a simply and practical method for the stability analyses of the cohesive homogeneous or heterogeneous soil slope, and its theoretical mathematical basis is the finite difference method and its precision depends on slice width and amount. In the chapter 1, based on the circular slip surface method, considering the case of fixed escaping point, the safety factor distribution map is drawn and analyzed, and the rule of the distribution of the safety of factor of composite slopes is studied. Because the objective function of the safety of factor is nonconvex, multi-variable, and existing many minimums, searching the most dangerous failure surface usually is difficult. Genetic algorithm is provided as a powerful tool and method for solving the problem. In the chapter 4, genetic algorithm is introduced, and through numerical examples it is shown that genetic algorithm is a global optimization method, which can overcome the drawbacks of local optimum widely existing in classic searching method. In the chapter 5, during the optimization, the influence of search efficiency of choosing search variable is studied, and author proposes a kind of choice, which the positions of two exit points and the sagitta of the slip surface are taken as the search variable (the sagitta depends on the dynamic positions of two exit points of the slip surface), The examples show that the choice method decrease search region, improve the efficiency of searching, and has applying foreground. In the chapter 6, based on genetic algorithm and pseudo-static method, searching method for the most dangerous slip surface and the according minimal safety factor are introduced, and the distribution map is drawn. Through the distribution map, it is shown that seismic load has limited impact on the distribution of the safety factor though expanding the low safety factor areas. Moreover, the relevant program for numerical computation and data process developed.