Study On Pulsating Characteristics And Seismic Stability Of Rock And Soil Slope

According to the microtremor observation data of 68 measuring points in the west of9 loess regions of Tianshui,the predominant period is analyzed using the method of spectral ratio;Based on the geological records of 7 boreholes and shear wave velocity distribution,Accordance with the One-dimensional dynamic soil response theory to calculate the soilnatural period,The results are more consistent both methods.Provide a reference to analyze the dynamic characteristics of major landslides and natural slopes in loess regions of Tianshui.In this paper,The influence of different potential azimuth seismic zones on the seismic stability of the slope is considered,FLAC3 D was utilized to simulate dynamic response of Zhengjiamo slope by used load increasing method to analyse slope stability with different incident directions of simple harmonic P wave,SH wave and SV wave.The conclusions from the researches of this paper are as follows:(1)Predominant period of typical slope in Tianshui: Slope cover layer thickness of20~40m about equal to 0.31s;Slope cover layer thickness of 5~10m about equal to 0.26 s.(2)The distribution of earthquake response plastic zone in Zhengjiamo slope differs from the incident directions of simple harmonic P wave.In general,Tensile damage zone by vertical incident are dense,which focus on slope surface with curvature dramatic change.Shear damage zone main focus on top in slope;Tensile damage zone by oblique incident are sparse distributed in slope surface,and shear damage zone is very deep,which extends toward the rear wall in slope interior.(3)The through area of earthquake response plastic zone in Zhengjiamo slope differs from the types of oblique incident simple harmonic wave.With load increasing,the trend of the plastic zone that along the Y axis reverse through by simple harmonic P wave;then the trend of the plastic zone is along the Z axis through by simple harmonic SH wave,which depth is biggest;the trend of the plastic zone that along the Y axis through by simple harmonic SV wave,which depth is minimum.(4)The stability coefficient of Zhengjiamo slope differs from the types of oblique incident simple harmonic wave.In general,the stability coefficient of SH wave is biggest;then SV wave is the smallest;P wave is between the two.(5)The smallest stability direction of Zhengjiamo slope similar from the types of oblique incident simple harmonic wave.Overall,the earthquake stability of slope is the worst by seismic wave oblique incident with azimuth 22.5°(West-south).This direction is close to the direction of potential source area in Tianshui,the slope boundary of this direction: side wall is high-steep and curvature larger change.(6)The vibration frequency has great influence for critical earthquake peak acceleration,when vibration frequency value predominant frequency,the critical earthquake peak acceleration is minimum,slope earthquake stability is the worst.