Failure Characteristics And Law Of Deposit Slope With Bedrock Under Different Coupling Of Earthquake And Rainfall

The instability characteristics and mechanisms of bedrock slopes were studied in this paper through model tests,based on different coupling of earthquake and rainfall.A comparative analysis was made among three factors: slope angles and soil types and different coupling modes of earthquake and rainfall.Then,the slope stability under post-rain earthquake was studied preliminarily.Finally,the slope failure modes,dynamic response and critical conditions of slope instability under different coupling of earthquake and rainfall were studied.The main conclusions are as follows:(1)Under different coupling conditions,the volume of sliding body under earthquake is the largest,that under rainfall is the smallest,and that under post-rain earthquake and post-earthquake rain is in the middle and basically the same.Under post-rain earthquake,the slope is divided into three velocity zones of high,medium and low during vibration,and the critical peak acceleration of instability decreases significantly.The critical acceleration of instability varies greatly due to the different order of earthquake and rainfall.(2)The critical instability condition of the gravel deposit slope decreases slightly under earthquake,compared with the silt deposit slope,and the failure mode changes from the shear-slip type of silt to the shallow-slip type of gravel soil.The dynamic transfer attenuation occurs inside the slope in seismic loads under post-rain earthquake,that is,the dynamic response at the interface is larger than that on the slope surface.(3)For the condition of double-layer deposit slope under post-rain earthquake,when the upper layer is fixed to silt and the lower layer changes from gravel soil to silt and then to medium sand,the critical condition of instability and the depth of the slip surface increases gradually,also the failure mode changes from local shallow failure to overall failure.The traction slip occurs under the lower layer of medium sand,while when the other two kinds of soil layer,it is push landslide.(4)For the condition of double-layer deposit slope under rainfall,when the accumulation changes from silt to sand-silt,the critical rainfall decreases from 202 mm to180mm,the creep phenomenon of upper soil disappears,and a tension crack appears in the medium sand layer.