| China is located between the circum-Pacific seismic belt and the Eurasian seismic belt.Seismic fault zones are developed.Strong earthquakes can induce large amounts of slope instability and damage,leading to serious geological disasters.The seismic stability analysis of the slope is very important for the building of high earthquake area buildings and infrastructure.At present,China’s current industry norms still follow the pseudo-static method,and they are still in the experience stage in theory and engineering practice.Most of these codes do not consider the effects of fluctuations and vertical seismic forces.They are only different in the selection of correlation coefficients,and the selection of coefficients is very empirical,which will bring great engineering risks.Therefore,systematic researches on the calculation of slope seismic force and stability analysis are of great significance in both theory and practice.The stability analysis method is the foundation of seismic slope stability evaluation.In order to find a more realistic evaluation method,this paper reviews the research progress of slope stability analysis methods,and analyzes the stability of slope stability according to the different calculation principles.The classification was carried out,including pseudo-static method,pseudo-dynamic method,and numerical method.The three methods were reviewed and summarized separately.The Fourier amplitude data of seismic waves at different seismic intensities were obtained through ground motion data processing.The Fourier frequency range of different ground motions was obtained,and the wave velocity data of common soil layers were collected.The frequencies,wave speeds,and wavelengths were obtained.The relationship gives the seismic wave length range of soil slopes.Simultaneously taking into account the influence of the input ground motion characteristics and the material properties of the slope body on the actual seismic response of the slope body,based on the basic principle of wave propagation,the distribution law of the ground motion response in the slope under normal incidence of the shear wave is studied to reveal the spectral characteristics of the input ground motion.The influence of the mechanical properties of the slope body itself.Then,starting from seismic factors,the effects of input ground motion characteristics and mechanical properties of slope materials on seismic responses are comprehensively considered,and the effects of wave effects on seismic forces and stability are analyzed to construct simple and practical,yet reflect the above-mentioned slope dynamic response.The main influencing factors and the essential characteristics of seismic force calculations are improved.Finally,the influence of vertical seismic force on slope stability is also discussed,and the following conclusions are drawn:(1)The predominant frequency of shear waves is concentrated in the range of 0.5-4 Hz,where the predominant frequency of shear waves in the near field(fault distance 20-60 km)is smaller than that of the far field(fault distance 60-200 km).Focused on 0.5-2.5Hz,the extraordinary frequency of the far field vibration shear wave is concentrated in 1-4Hz;the excellent frequency of the longitudinal wave is concentrated in 1-7Hz,and the excellent frequency of the near-field or far-field vibration longitudinal wave has no regularity,and the excellent frequency range It is larger than the shear wave;the wavelength range of different material slopes under different ground motion conditions is obtained.(2)By analyzing the Seismic Coefficient Ratio(referred to as SCR,the ratio of seismic coefficients calculated from the pseudo-dynamic method to the pseudo-static seismic coefficients),the method based on the wave theory and the pseudo-static method are compared.Whenλ/H(ratio of wavelength to slope height)is greater than 10,SCR=1.The results of pseudo-static method and wave theory are basically the same.Whenλ/H is less than 10,SCR<1,and SCR decreases withλ/H.Reduction,quasi-static method and calculation result based on wave theory are different.The difference increases with the increase of K_h(quasi-static quake coefficient),so whenλ/H is less than 10,the wave effect needs to be considered.Impact of slope seismic force and stability.The SCR values??corresponding to differentλ/H of the soil slope are given.The minimum value of the transverse waveλ/H of the soil slope is 0.5 and the minimum value of the longitudinal waveλ/H is 0.8.The corresponding SCR_h minimum value is 0.16 and the SCR_v minimum value is0.22.And after analysis,it is a high probability event thatλ/H is less than 10 in the soil slope.Therefore,it is necessary to consider the fluctuating effect when the soil slope is used to analyze the ground motion stability.(3)It is found that the vertical seismic force has little effect on the safety factor in the calculation of the pseudo-static method and can be almost ignored.However,considering the fluctuation effect,the vertical seismic force will have a greater influence on the safety factor,and does not consider the vertical Seismic forces will increase the safety factor,so it is very dangerous to ignore vertical seismic forces in dynamic analysis. |
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