Large-scale Shaking Table Test Study On Dynamic Characteristics Of The Bedrock And Overburden Layer Slope And Gravity Retaining Wall

The bedrock and overburden layer slope are a common type of slope structure and are widely distributed in the central western regions of China.In the paper,model tests are designed,fabricated and loaded on the bedrock and overburden layer slope using similar criteria.Shaking table tests are used to record the failure phenomena and obtain slope acceleration and displacement data and analyze.A shaking table test is conducted again with a gravity wall designed and produced.The slope protection mechanism of the retaining wall is analyzed through the sensor results,and its effect on seismic reinforcement is evaluated,as follows:(1)Large-scale shaking table test of dynamic characteristics of high and steep the bedrock and overburden layer slope under earthquake action.The test shows that both the seismic waveform and seismic intensity have an effect on the slope peak acceleration along the elevation evolution.The influence of the waveform on the peak acceleration amplification factor in elevation is mainly reflected in the changing amplitude.The peak acceleration amplification coefficients are positively correlated with the elevation under different earthquake intensity.The Fourier spectrum of acceleration on slopes has a significant increase in the amplitude of the higher frequency band from 15 Hz to 25 Hz along the elevation,and the amplitude of the acceleration response spectrum along the short period of about 0.05 s along the elevation shows a clear lifting effect.When the slope collapses,first of all,there is a serious debris flow on the slope surface and it accumulates on the slope bottom,cracks appear on the slope top and gradually develop downward,and finally the overlying accumulation body collapses along the weak interlayer.The acceleration Hilbert spectrum shows that the weak interlayer absorbs the high-frequency seismic energy during the ground motion,amplifies the low-frequency part of the energy,the energy intensifies in the whole time course,and the energy difference in the low-frequency part of the sliding bed slide belt intensifies during the destruction.The sliding zone of the slide bed has obvious motion inconsistency,and the evolution of the structural acceleration Fourier spectrum and acceleration Hilbert spectrum along the elevation.The rules are consistent.(2)Large-scale shaking table test of the bedrock and overburden layer slope reinforced by gravity retaining wall.The test shows that the evolution of seismic waveform on the peak acceleration along the elevation is mainly reflected in the amplitude.The influence of the seismic waveform on the earth pressure is relatively limited,and the seismic intensity will change the distribution of the earth pressure.In the process of gradually increasing the seismic intensity,firstly,it is the displacement of the upper structure of the retaining wall under the action of the slope and earthquake,and the squeezing is reduced.After that,the retaining wall is mainly displaced in the lower part under the action of the earth pressure,and finally the lower part of the retaining wall is simultaneously displaced.The difference in the evolution law of the acceleration Fourier spectrum along the elevation caused by different seismic waves is mainly reflected in the energy amplitude.Under the action of seismic waves with different intensities and waveforms,the acceleration amplification factor fluctuations at the measuring points along the elevation distribution near the retaining wall are relatively smooth,and the evolution rule of the amplification factor is basically the same,indicating that the gravity retaining wall improves the transmission law of peak acceleration.The effect of material heterogeneity on the underlying bedrock-weak interlayer-overburden is reduced,and the gravity retaining wall is more obvious for the acceleration Fourier spectrum evolution of seismic waves from the underlying bedrock-weak interlayer-overburden weakening,in which the weak interlayer still has an amplification effect on the partial frequency band Fourier spectrum,Hilbert spectrum,etc.,indicating that the weak interlayer is still a structure that has a greater impact on the seismic response of the soil.