Seismic Response Analysis Of Fenghuang Mountain Site And Large Scale Shaking Table Test

The site stability evaluation of project is the important content of the site address selection. If significant projects, such as nuclear power plants, DAMS, docks, etc, are built on unstable site, once losing stability, which will cause serious consequences. Therefore, site stability evaluation is the premise for the construction of significant projects.In this paper, Fenghuang mountain located in a highly seismic zone of our country was selected as a prototype to carry out the large-scale shaking table test. Firstly, the impact of the acceleration propagation was explored when there is site fault (Fault clay interlayer) or strong weathered zone in the site, and then the critical acceleration of site fault (Fault clay interlayer) or strongly weathered zone and effect of displacement of potential sliding zone was explored, finally, the site stability of the disposal site which contains site fault or strong weathered zone was discussed. The conclusions are as follows:1. The results showed that when the peak ground acceleration (PGA) of shock waves is not greater than 0.33g, the PGA of the weathered silty shale which is on the bottom increases with increasing elevation, when altitude reached the strong weathering zone, since structural stability of this layer is weakened and the rigidity is reduced, the soil exhibited strong nonlinear characteristics, PGA attenuation effect is obvious, when altitude reached the upper silty clay with stone blocks, PGA increases with elevation increases, the value is up to its maximum when altitude reached surface of the site.2. The test results show that when the PGA of shock waves is not greater than 0.33g, the greater the shock waves peak loaded, PGA amplification factor is smaller.3. The effect of Fourier spectrum amplitude which is caused by elevation is not obvious, it shows a slightly increase with increasing elevation, the Fourier spectrum amplitude of the soil which has the same characteristics are basically the same, the change of the soil characteristics will cause significant change of Fourier spectrum amplitude, soil characteristic change is the main reason for the changing of the magnitude of the Fourier spectrum.4. The analysis showed that Fourier spectrum amplitude of the soil which has the same characteristics are basically the same at low frequencies (0-2.3Hz), Fourier spectrum amplitude are slightly enlarged at high frequencies (2.3-8 Hz), the spectral characteristics are basically the same; when the seismic waves spreaded between the different soil, the strong weathering zone has little effect on low frequencies (0-2.3Hz) of Fourier spectrum, it has a very significant amplification effect on high frequencies (2.3-8 Hz) of Fourier spectrum.5. Response spectrum analysis shows that, when the PGA of El centro shock waves is 0.15g and the soil is saturated aqueous state, the characteristic period of soil surface which is away from the local slope is 0.2s, the characteristic period of the centro of local slope is 0.3s, the characteristic period of the soil which has the same characteristics remain at 0.3s, attention should be attached in engineering applications.6. The analysis shows, when the shock waves is 0.15g El centra, there is a difference between the characteristic period of saturated aqueous state and natural water status, the characteristic period of saturated aqueous state is greater than the case of natural water status, the characteristic period of saturated aqueous state is about 0.3s and the natural water status is about 0.15s.7. The experimental data shows that the displacement of the top of slope is greater than the bottom of the slope, the displacement of the centro of slope is minimum; the displacement of saturated aqueous state is significantly greater than the case of natural water status. Slope displacement changed slightly and it can be inferred that the slope stability has a good stability.8. Strain regularity of the layered soil shows no difference with the regularity of PGA amplification factor which the factor is reduced at the strong weathering zone, since structural stability of this layer is weakened and the rigidity is reduced, the soil exhibited strong nonlinear characteristics, strain increased with increasing elevation, he strong weathering zone will cause local strain increases, the local site conditions such as local slope will cause strain nonlinear changes, it has little effect on the overall stability combined with local slope displacement analysis.9. Under the conditions of Wenchuan 0.33g wave which is set in advance, the site stability factor is 3.16, the critical acceleration of potential slipping area is 1.42g. This result shows that the site has a good stability.