Experimental Study On The Instability And Deformation Mechanism Of Loess Slope In Northern Shanxi Province

As a common geological disaster in the Loess plateau,Loess landslide brings a great threat to the life and property safety of local people.Therefore,based on the concrete project case,this paper studies the instability and deformation mechanism of loess slope under the action of excavation rainfall and earthquake through field model test and vibration table test.By collecting and analyzing the natural geography and geological conditions of the study area,combined with its geological analysis and field model test,the mechanism of instability and deformation of loess slope under excavation rainfall mode and other main conclusions and suggestions are obtained,and the instability and deformation mechanism of loess slope under seismic action and its main conclusions are obtained through the experimental Study of vibration table.The main research contents and main conclusions of this paper are as follows:(1)The landslide deformation mechanism,which is affected by the excavation of slope foot and the combination of rainfall,can be summed up as: natural slope-excavation unloading-unloading fracture expansion-rainwater infiltration-soil deterioration damage-sliding Harai shear failure-slope burst instability;(2)The excavation at the foot of the slope is the main factor affecting the sliding of the slope,and the height of the excavation face affects the stability of the slope.Rainfall is the inducing factor of slope sliding,and the instability of slope induced by rainfall has time cumulative effect.(3)The acceleration dynamic response of the overlying slope in the early stage of the push-type landslide sliding is violent,and the dynamic response of the acceleration of the lower cladding slope is violent,which shows the upper trigger of the slope and the gradual deformation mode of the lower part.(4)Through the test of large vibration table,comparing the response of slope with or without excavation under the action of earthquake,the process of deformation and failure mechanism of loess slope under seismic load,"natural slope-seismic inertial force disturbance-tensile fracture expansion-soil deterioration damage-sliding Harai shear failure-slope burst earthquake subsidence instability" is revealed.(5)The excavation side slope is next piece than that of the slope without excavation,and with the increase of the peak load acceleration,the crack gradually runs through the tensile failure,and under the action of the peak failure,the excavation side slope shows obvious collapse of the slope and the failure phenomenon of the earthquake subsidence.(6)The acceleration response of the measuring points on both sides of the slope shows obvious elevation amplification effect on the section,showing obvious amplification effect on the plane surface,and in the excavation side slope,the elevation amplification effect and the surface amplification effect are more obvious;(7)Through the analysis of acceleration spectrum,the maximum energy proportion of frequency band of each measuring point occurs in the low frequency section.With the increase of frequency band,the energy proportion decreases gradually.It shows that the slope soil can amplify the low frequency section of acceleration response and filter the high frequency section.The excavated side slope at the foot of the slope has greater energy than the excavated side slope at the same position.The proportion of slope foot excavation indicates that the dynamic response of slope will be increased and the possibility of slope instability will be increased.