| China is located at the intersection of the Rim of the Pacific and the Eurasian seismic belt.The compression and tension between the plates have led to the development of fault zones.High frequency,wide distribution,and strong activity have become the characteristics of my country's seismic activity.With the continuous development of my country's roads and railways,many large-scale transportation facilities will be built in mountainous areas and areas with strong earthquakes,which will cause landslide disasters.This paper takes Qinghai Yushu 0# landslide group,2# landslide,and 3#landslide as the main research objects,and takes the softening effect of dynamic load on the strength of rock and soil and the law of seismic wave propagation in the slope as the theoretical basis.The actual damage characteristics in the earthquake are the basis.Based on a large number of field investigations and data analysis,the geomechanical theory is used to simplify the geomechanical model,and the mechanism of earthquake-induced landslide instability is studied through large-scale shaking table tests.Based on this,the prevention and control structure optimization design is carried out.Finally,the prevention and control structure optimization verification is carried out through the shaking table test.The main conclusions are as follows:(1)Based on the investigation of Yushu earthquake disaster along the highway,the types of the earthquake,the regional engineering geological properties,the types of earthquake induced secondary disasters and the main types of earthquake side(sliding)slope are systematically expounded.Because the earthquakes are all located in mountainous areas,and according to their own special topographical and geological conditions,it is pointed out that the surface damage in this area is characterized by the most extensive and typical distribution of earthquake disasters in single sliding surface accumulation layer and multi sliding surface accumulation layer.Yushu 7.1 earthquake occurred on Ganzi Yushu Fenghuoshan fault,which was caused by active fault.The intensity of the epicenter reached IX.According to the investigation along the disaster highway after the earthquake,the main slope disaster types mainly include: single sliding surface accumulation layer,multi sliding surface accumulation layer,steep bedding layer,steep anti dip layer and fill embankment slope,among which the single sliding surface accumulation layer and multi sliding surface accumulation layer are the most widely distributed and typical.(2)The acceleration amplification factor of a single-sliding surface accumulation layer landslide under the action of an earthquake is greatly affected by the landslide medium.Under the premise that the intensity of the ground motion remains unchanged,with the continuous increase in elevation,the propagation speed of seismic waves gradually increases.(3)According to the calculation of the safety factor of the single-sliding surface accumulation layer landslide point safety factor of Airport Road 2# and 3#,the application of EPS piles improves the anti-sliding effect of the single sliding surface landslide.With the continuous increase of the input seismic wave intensity,cracks First appeared at the rear edge of the slope,and the cracks gradually penetrated.(4)The sliding zone soil has an obvious blocking effect on the acceleration amplification effect of the landslide.When the sliding zone soil is in the elastic state,the sliding zone soil has little influence on the dynamic acceleration amplification effect of slope body,and the amplification coefficient is mainly affected by topography,showing the amplification effect with the increase of height.When the sliding zone soil is in the plastic yield state,the ground motion energy is absorbed by the sliding zone soil in the upward propagation process and converted into plastic strain,and it is difficult to continue to transfer the load upward,so the peak acceleration does not increase.(5)Compared with single-slip surface accumulation landslides,the seismic damage effects of multi-slip surface landslides are quite different.For a single-slip surface landslide,when the input seismic wave direction is X,XZ direction,the failure process mainly starts from the position of the slope toe and the top of the slope,and when the input seismic wave direction is Z direction,the failure process mainly starts from the position in the slope.Start.For multi-sliding surfaces,with the continuous increase of earthquake intensity,landslide deformation first starts from the sliding surface.(6)Through the dynamic response analysis of three kinds of seismic waves(sine wave,Yushu horizontal wave,Yushu vertical wave)on the slope,it is found that the sine wave has the greatest influence on acceleration amplification factor,velocity amplification factor,displacement amplification factor and residual displacement,Yushu has the least impact on vertical waves.The greater the peak acceleration,the more disorderly the slider changes,indicating that the slope is constantly undergoing plastic failure.(7)With the increase of earthquake action,the location of the sliding surface of ordinary piles is prone to shear failure.However,the peak acceleration of the EPS pile mountain side is significantly reduced,especially at the position of the sliding surface,the reduction effect is the most significant,and the pile body exhibits an "S"-shaped change along the elevation.(8)The slope has a certain filtering effect on the high frequency band of seismic waves.The EPS pile structure is relatively safe,and the low frequency(0.5-10Hz)seismic wave has a greater impact on the structure.The greater response to the structure is mainly concentrated in the low frequency band.Polystyrene foam(EPS board)is used as the shock absorption layer.The EPS pile has a good shock absorption effect on the side slope of the mountain,especially the sliding surface position.The damping effect is related to the spatial effect of its distribution location.EPS only plays a role of energy dissipation,and does not change the spectral characteristics of the structure. |
PDF Full Text Request