Study On The Dynamic Response Of Donghekou Slope Based On Ambient Noise Test And Spectral Element Simulation

The dynamic response of slope is essentially the result of the influence of earthquake on the geological environment factors of slope,in which the influence of the predominant frequency and source characteristics of slope site on the dynamic effect of slope is of great concern.In this paper,taking donghekou slope as an example,the ambient noise data of 44 measuring points in donghekou landslide accumulation area,landslide source area and slope on both sides of the north and south of the landslide are obtained by using the ambient noise test method.The spectral characteristics of the slope are revealed by using the horizontal to vertical spectral ratio method(H / V),and the two-dimensional discrete element numerical comparison model of pure terrain and stratum is established,as well as the location of different seismic sources and the location of different seismic sources With the same source frequency and different time function,the three-dimensional spectral element method numerical model summarizes the dynamic response characteristics of donghekou slope as follows:(1)The H / V spectral ratio of ambient noise reveals that the amplification effect of bedrock site spectral ratio in the source area of donghekou landslide is stronger than that of other test sites,and has obvious directional characteristics.The amplification effect of NS component in the horizontal direction is stronger than EW component in the horizontal direction,the maximum amplification system number is about 2.27,and the predominant frequencies of NS component and EW component are 7.36 Hz and 3.66 Hz respectively.(2)Using UDEC two-dimensional discrete element to build the homogeneous reference model(pure terrain)of the original slope and the soft hard lithology interbedding model of the combination stratum,it shows that the terrain amplification effect on the top of the slope is the strongest,and the soft hard lithology interbedding has obvious difference on the dynamic amplification effect of the slope.When the current soft and upper hard media contact,the dynamic response of the upper hard slope is weaker than that of the homogeneous.The dynamic response of the upper soft slope is stronger than that of the lower hard one when it is in contact with the upper soft medium.(3)Using spectral element method to build three-dimensional wave field simulation results show that the farther the source is from the slope,the smaller the slope amplitude;the higher the source frequency,the greater the PGA and amplitude value of the slope,and the more obvious the amplification effect of the prominent terrain,the slope back slope amplification effect is affected by the direction of the source incident;the particle motion direction and spectral score of the slope thrust strike slip dual couple point source model The analysis shows that the dynamic effect is stronger in the slope tendency,which shows that the failure of Shikan fault on the slope side of donghekou landslide has an important control effect on the dynamic instability.(4)The analysis of the ambient noise data and the simulation results of UDEC show that the two excellent frequencies are in good agreement.Compared with the results of ambient noise data analysis and wave field simulation,it is found that the dynamic amplification curve of donghekou slope simulated by a 2# point source located directly below the slope and with the main frequency of 2Hz is more consistent with the analysis of ambient noise data.