Study On Failure Mode And Mechanism Of Two-side Slopes Based On PFC^2D Under Cyclic Dynamic Load

Earthquake is one of the important factors to induce landslide instability.In this paper,the failure mode and mechanism of double-sided slope under cyclic dynamic load are studied by using particle dispersion element method software(PFC^2D).Through shaking table test,the deformation and failure process and dynamic response law of double slope under cyclic dynamic load under three groups of working conditions are studied.The PFC^2D numerical model of double-sided slope is established and simulated.The results are compared with the data recorded in the shaking table test,and the validity and applicability of the numerical model are demonstrated.The microscopic failure process and mechanism of double-sided slope under three groups of working conditions are further studied by numerical simulation.It is concluded that under the action of cyclic dynamic load,the failure modes are vibration loose-shallow slip,tension-shear-slip and shock collapse-slip,respectively.The failure mechanisms are tension-induced,tension-shear effect and double slope co-tension effect under reciprocating dynamic load,respectively.The numerical simulation calculation of the failure process of double-sided slope top under three groups of working conditions is carried out in order to compare the difference of failure process under dynamic condition.First of all,combined with the theory of ultimate bearing capacity,the rationality of this method is proved.Under the condition of limit force,the failure process of double-sided slope under three groups of working conditions is studied.It is concluded that the static downhill is mainly destroyed along the slip line,and the slip line increases gradually with the continuous loading.The difference is that the stronger the fracture of the slip surface is with the increase of cohesion.However,under the dynamic force,the double-sided slope slip surface is usually a main slip surface,and there may be a secondary slip surface on the sliding body which slips along the main slip surface.On the basis of working condition 2,the failure process of internal double slope with cracks is further studied.It mainly includes four groups of working conditions,such as horizontal cracks in the middle of the slope,oblique cracks in the middle of the slope,horizontal cracks in the left foot of the slope and random cracks obeying Markov distribution in the slope.It is concluded that under the dynamic action,the failure of the double slope with preset cracks is the slip fracture along the preset cracks,and the obvious fracture concentration occurs at the preset cracks,and the slip surface runs through along the development of the preset cracks.On the basis of working condition 2,the other parameter is increased or decreased by keeping the slope and height unchanged respectively,and the working conditions of a total of 7 different geometric parameters are studied.It is concluded that with the increase of slope and slope height,the failure of slope is the development trend of stability-local failure-progressive failure-tension-shear slip-tensile fracture slip.And with the increase of the slope height and slope,the sliding body has more integrity,and the sliding surface is deeper.