Study On The Instability Mechanism Of Loess Slope Based On Shaking Table Model Test

Loess is a special kind of sedimentation on the earth that formed in theQuaternary period. The distribution of loess in China is mainly concentrated in themiddle reaches of the Yellow River, such as Gansu, Shanxi, Ningxia, Shanxi, Henan,and Qinghai provinces. It is serious with the earthquake disaster and geologic hazardrelate in loess because the complex topography and the variety of active tectonics inloess plateau. The special property of loess, compared to another, is the dynamicfragility of loess caused by the overhead pore structure and weak cementation. Inaddition, the loess plateau for earthquake prone area. It is estimated that the area ofseismic intensity as high as VI degree is as large as335100km2. Consequently, themultiple, instability, complexity and catastrophe exists in loess slope earthquakedisaster determined by the high seismic activity in loess plateau and the specialengineering properties of loess.Consequently, the dynamic response and the instability mechanism of the typicalloess slope under seismic excitations should be systematical studied with shakingtable model test. It is useful to prevent the slope in loess plateau with high seismicactivity. Scope and production studied in this paper as follows:1. Studying the dynamic response of the typical loess slope model based onshaking table model test. The results show that, there are certain properties thatsurface and vertical amplification of the loess slopes with the input seismic wave.2. The results of the studying with seismic Fourier amplitude spectrum showthat, It is stronger destruction effect on the typical loess slope when input the groundmotion containing less dominant frequency component. And there is the function offiltering the frequency below20Hz. Meanwhile, there is obvious amplificationbetween the22Hz and32Hz.3. There is significant influence on dynamic response of the typical loess slopewhen input different seismic loading direction. The results shows that it is seriousdestroy on the typical loess slope when input the horizontal ground motion,4. The top of the typical loess slope appear to a series of tensile cracks when it suffer the seismic intensity as high as VIII degree. It is extremely easy to occur thatthe landslide of loess seismic subsidence when the typical loess slope suffer theseismic intensity as high as IX degree.5. Tensile stress distribution in Loess slope model presumed by the stress sensordata in the horizontal seismic action have a better fit with shaking table test results.And the circumstances under42gal Wenchuan load, the maximum tensile stress slopemodel appears at the top of the slope. Its value reaches58kpa. Meanwhile, the strainsensor data confirms this typical loess seismic subsidence phenomenon occurred crestslope model under earthquake..6. The results combined with the shaking table model test and ABAQUSprogram, Got under seismic loads loess slope acceleration amplification effect, stressand deformation characteristics, and its main results include: ground motions as timeincreases, the horizontal displacement of the top of the slope is gradually increasing;slope with increasing height, acceleration occurs significantly increasing trend;under seismic loads, top model apparent tensile stress, the maximum tensile stress is0.05Mpa. The maximum compressive stress is located at the junction of loess andbedrock surface compressive stress of up to0.15Mpa; the simulation results withshaking table test results were compared with the analysis found that the higher thedegree of matching between the two, which further validates the typical loess slopedynamic Stability earthquake model.