Slope Stability Analysis Under Two-dimensional Steady Seepage Based On IRMO Algorithm

Among the factors affecting slope stability,seepage plays an important role,so it is necessary to correctly consider the seepage effect.In this thesis,the characteristics of seepage force are analyzed,and a reasonable simplified form of seepage field is proposed.The calculation formula and solution method of the minimum safety factor of slope based on the total stress form and effective stress form of Janbu method are derived as the objective function of the improved radial movement(IRMO)algorithm.Therefore,the search of the critical slip surface and the calculation of the minimum safety factor of the slope are transformed into the mathematical problems of the vector space path optimization problem and the functional extremum solution.The slope stability analysis theory under the action of two-dimensional steady seepage based on the IRMO algorithm is proposed.The main research work and conclusions of this thesis are as follows:(1)The mechanism of seepage action on the strip block in the slice method is discussed,and the size,direction and position of the seepage force in the force analysis of the strip block are obtained.According to the actual seepage field,the distribution form of the seepage field is simplified.Strict Janbu method and simplified Janbu method for slope stability analysis under the action of dimensionally stable seepage,the calculation expressions of the safety factor under the total stress form and the effective stress form,and the solution method of the safety factor expression.(2)The inertia weight parameters in IRMO algorithm are improved,and a dynamic inertia weight strategy based on particle fitness is applied to balance the global and local search ability of the algorithm.A multidimensional vector composed of length variables and several angular variables is used to represent the non-circular sliding surface of the sliding surface,which is one-to-one correspondence with the M-dimensional vector representing the particle position in the IRMO algorithm.The derived minimum safety factor calculation expression and solution method are used as the objective function of the IRMO algorithm.The process of searching the sliding surface and solving the safety factor of the IRMO algorithm is realized,and the critical sliding surface is searched.(3)Based on the obtained theory,the slope stability analysis program under two-dimensional stable seepage based on IRMO algorithm is compiled.The calculation examples of homogeneous and heterogeneous soil slope under two-dimensional seepage are used for comparative analysis to verify the effectiveness and advantages of this program.(4)The stability analysis of the water-bearing slope is carried out by using the program in this thesis.The analysis results show that the minimum safety factor of the slope is significantly reduced by the seepage of water,and the change of waterline outside the slope seriously affects the stability of the slope.During the change of the water level,the safety factor of the slope rises with the rise of the water level,and decreases rapidly when the water level falls.Therefore,the decline of water level will aggravate the instability of slope,in which the decline rate of water level and the permeability coefficient of slope are important factors.The faster the decline rate of water level and the smaller the permeability coefficient,the greater the decline rate of safety factor.