Numerical Simulation Research On Stability Of Slope Under Seismic Load Patterns

China is a nation with high activity and high-frequency of earthquakes.The researches of the slope stability are promoted by the enormous destroy made by the landslides,collapse cause by earthquakes.However,the seismic load effect on slope stability is extremely complicated and uncertainty,which affected by the properties of slope and behaves of seismic load.For a concrete slope,the potential seismic load plays the leading role.In traditional seismology,the seismic motions were explained preferably by the effect of the three essential elements of seismic wave: the seismic load,the frequency,the duration.But,the seismic load pattern which includes the direction and properties of seismic wave are ignored.In this paper,equations of kinematics,geometry,physics and three-dimensional wave were used to derived the equations,which obtained the effect of different seismic load pattern on the bottom of a slope.And the excitation scheme of different incident directions of seismic wave on a slope was built by Huygens? principle.FLAC3 Dwas utilized to simulate dynamic response of Panlongyuan loess slope by used load increasing method to find critical earthquake peak accelerations with different incident directions.The conclusions from the researches of this paper are as follows :(1)The stability of Panlongyuan loess slope differs from the seismic load pattern.The critical earthquake peak accelerations are regularly changing.It is more danger for the rock soil mass to vibrate vertical than horizontal.In general,Panlongyuan loess slope shows a low seismic stability when the seismic waves' incident angle is 315°(northwest).(2)The distribution of plastic zone in Panlongyuan loess slope differs from the seismic load pattern.P wave dominate the shear damage,whereas the damage of Panlongyuan loess slope was tensile fracture at the top accompany shear damage at bottom when S wave incident.(3)The response values on the cross section of Panlongyuan loess slope plastic zone were magnified.Beside,the response and deformation of slope rock mass where is nearby the shoulder of slop is bigger,it is easy to damage.The monitoring points of plastic zone through the cross section of slop is trend to move along the direction of the-Y axis(south).(4)The sliding failure of Panlongyuan loess slope related to not only seismic load pattern,but also gravity.So gravity must be considered in the analysis of slope failure mode.