Study On Evaluation Method Of Long-term Stability Of Rock Slope In Strong Earthquake Area

Earthquakes frequently occur in Southwest China,and a large number of slopes are damaged by strong earthquake accumulation.They are very vulnerable to landslide disasters caused by rainfall and human engineering activities,which directly threaten the safety of major projects.Therefore,it is very important to establish the long-term stability evaluation method of rock slope after earthquake.Taking the typical landslide geological disaster in southwest China as the research object,this thesis carried out the model test of rock slope vibration table,and studied the dynamic response characteristics,dynamic evolution laws and failure mechanism of slope model under earthquake load.A long-term stability discriminant Index system for rock slope based on dynamic amplification effect and plastic effect is proposed.Based on the information of ground motion station,the long-term stability evaluation process of rock slope after earthquake is designed and applied in practical engineering activities.As for the bank slope of Huaping side of Jinsha Jiangte Bridge,a vibration table model test was designed and carried out to study the dynamic response of rock slope under earthquake.The mixed materials of cement,sand,clay and iron powder were used to simulate basalt,and the PVC plate simulated the structure surface of tuff.By changing the type and direction of input seismic load and increasing the seismic intensity,the response of seismic accumulation on rock slope was studied.The acceleration and displacement response results revealed that the dynamic response of the slope was stronger than that of the vertical seismic load under the horizontal seismic load.And the acceleration amplification effect was mainly concentrated in the middle and the top of slope,which can be up to 5 times.The permanent displacement mainly occurred in the middle of the slope,and the maximum can reach 38 mm when the damage was carried out.The failure mode of slope is as follows: The sliding surface was cut off along the steep tilt structure surface of the rear edge,the penetrating structure surface was sliding,and the lower slope foot was cut out.The feasibility of acceleration peak,acceleration amplification effect,displacement peak,permanent deformation,dynamic safety factor and plastic effect as the evaluation index of long-term stability of rock slope was analyzed in detail.Combined with the data of acceleration and displacement collected from vibration table test,the dynamic evolution law of rock slope was studied,and the applicability of the above evaluation index was clarified.The acceleration amplification effect and plasticity effect were proposed as the evaluation indexes of long-term stability of rock slope.Taking the influence area of Chenghai fault zone as research object,the simplified geological hazard evaluation and early identification method of regional landslide were put forward.Based on the information of ground motion station and field investigation,the landslide danger zone was identified in the research area,and the long-term stability of rock slope was recognized early in the study.The results showed that under earthquake load,landslide danger zone was found in high slope near Chenghai fault zone,evaluation Index of acceleration amplification effect and plastic effect both revealed that some slopes were affected by historical earthquake,and landslide monitoring should be carried out in unstable stage.