Research On Limit Equilibrium Analysis Method Of Seismic Slope Stability Based On Pseudo-dynamic Method

Earthquakes are one of the main factors that induce slope instability.Due to the strong tectonic movement,seismic fault zone are very developed in our country,therefore,the frequency of earthquakes is higher.The ground landslide is seriously damaged by the earthquake,causing huge casualties and property losses.Therefore,the study of seismic slope stability evaluation methods is of great significance.At present,the pseu.do-static method is used for the sta.bility analy.sis of seismi.c slopes.However,the pseudo-static method simplifies the seismic force to a constant inertial force without considering the characteristics of the seismic wave,and the calculated result is too conservative.In this paper,based on the principle of pseudo-dynamic method,and with the swedish slice method,bishop's method and simplified janbu's method in the traditional limit equilibrium method of static slope stability analysis,the slove formula of seismic force and safety factor of seismic slope are invented,and the method of seismic slope stability considering wave effect is proposed.According to the derived formula,the basic formula is given based on MATLAB software,the program of seismic slope stability analysis is compiled.And the program interface software is further developed.With the help of the developed software,the influence factors and laws of seismic dynamic characteristics on seismic slope are discussed.The main results are as follows:(1)In this paper,the pseudo-dynamic method is combined with the Swedish slice method,the simplified Bishop method.and the simplified Janbu method.in the vertical slice limit equilibrium method,and the calculation formulas of seismic force and safety factor of seismic slope are derived.Constructed a method to analyze the ultimate equilibrium stability of seismic slopes.(2)The program of pseudo-dynamic seismic slope calculation is compiled and verified to be effective and reasonable.And developed a visual operation interface.(3)The effects of the initial phase of the seismic wave,the shear wave velocity of the slope material and the remarkable frequency on the stability of the seismic slope are analyzed,and the results show that: the influence of initial phase on stability is mainly the magnitude and direction of seismic force in slope.The safety coefficient calculated by different initial phases fluctuates periodically.Therefore,in the analysis of seismic slope stability,it is necessary to screen the phase to find out the safety factor corresponding to the most dangerous condition;the influence of shear wave velocity and predominant frequency on the stability is inversely proportional,that is,with the increase of wave velocity,the slope safe stability become low,and with the increase of frequency,the slope safe stability become high;(4)The influence of the wavelength and slope height ratio on the safety factor of the pseudo-dynamic method is further analyzed,and the results show that: When ?/h is higher than 2,the safety factor calculated by pseudo-dynamic method is close to that by pseudo-static method,and when the ratio is greater than 10,pseudo-dynamic method is basically the same as that calculated by pseudo-static method;but when ?/h is lower than 2,the safety factor calculated by pseudo-dynamic method is greater than that calculated by pseudo-static method,and with the decrease of the ratio,the difference between pseudo-dynamic method and pseudo-static method is greater,And the closer to the result of static method.Therefore,in engineering practice,the ratio of wave length to slope height should be determined,which has important theoretical significance for the stability analysis of seismic slope.