Research On Seismic Active Earth Pressure On Retaining Walls Based On Curved Rupture Surfaces

In the field of seismic design,it is important to study the earth pressure on the retaining wall.The acquisition of the earth pressure on retaining walls under seismic condition mainly includes theoretical calculation,numerical analysis and model test.The theoretical calculation methods of seismic earth pressure of retaining wall mainly include pseudo-static method,pseudo-dynamic method and elastic wave method.And the numerical analysis methods mainly include finite element method and discrete element method.At present,in the theoretical calculation and deducing of seismic active earth pressure of retaining wall,the critical failure surface form behind the wall is always assumed to be plane.Based on the principles of pseudo-dynamic method,the critical failure surface of the backfill soil is assumed to be a composite surface in the form of logarithmic spiral and straight line.Then,the effects of phase change,horizontal seismic coefficient,amplification factors and the internal friction angle on seismic active earth pressure intensity distribution are analyzed and discussed.By contrast in this paper,the present study and pseudo-static method,pseudo-dynamic method in planar failure surface form of the distribution of seismic active earth pressure,results show that under the same conditions,the proposed method receives a bit lower value of seismic active earth pressures.Through finite element numerical analysis,it is verified that the critical failure surface of the backfill soil in the state of active instability conditions is curved,and it is consistent with the composite form of the logarithmic spiral and straight line assumed by the present study based on the pseudo-dynamic method.On the basis of the critical failure surface of the backfill soil as a curved surface,the results of the finite element analysis and the pseudo-dynamic method are compared,and the difference of the finite element method and the pseudo-dynamic method in the calculation of seismic active earth pressure on the retaining wall is analyzed.The results show that,in the finite element analysis,the acceleration amplitude of the earth filling behind the wall has obvious amplification effects along the depth of the retaining wall,which is related to many factors.Linear distribution of amplification factors is generated under low frequency seismic load,while nonlinear distribution of amplification factors is generated under high frequency seismic load;the higher the retaining wall,the greater the amplification factor.According to the amplification factors of acceleration amplitude,the distribution of seismic active earth pressure on retaining wall is close to that obtained by finite element analysis after the input seismic acceleration is modified by pseudo-dynamic method.